Jump to Content

Increase text size Decrease text size

Search Content Type

Search
Advanced Search

Proceedings

Search Issue | RSS Feeds

RSS

World Environmental and Water Resources Congress 2008: Ahupua'a Proceedings of the World Environmental and Water Resources Congress 2008

May 12–16, 2008 Honolulu, Hawaii

Editor(s): Roger W. Babcock, Raymond Walton

Buy this book

SECTION LISTING

Add

Add Items to Cart

View

View Items in Cart

SELECTED: Export Citations | Show Only | Show All | Show/HideHide Summaries | Add to MyArticles | Email

back to top

MENA/ATI TOWARD SUSTAINABLE WATER RESOURCE MANAGEMENT IN THE MIDDLE EAST AND NORTH AFRICA (MENA) REGION

Select this Article		Best Management Practices (BMPs) for Surface Water Pollution in Developing Countries Fidelia N. (Ola) Nnadi, Ph.D., P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)1 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract This study investigates the water issues as they relate to social and economic development in Nigeria, West Africa. The study evaluates the quality of surface drinking water sources in selected highly polluted areas to define the extent of pollution. It accounts for human activities as they relate to water pollution and water‐borne diseases, and identify both structural and non‐structural Best Management Practices (BMPs) for pollution abatement. The structural BMPs are potential technology that could be manufactured in Nigeria. The study finally suggests a Water Access Awareness Program (WAAP) to educate the people on the problems.

Select this Article		BMPs as a Water Balance Asset in Arid Regions A. C. Rowney, G. Yamout, and J. Besmehn ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)2 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract This paper explores a few of the factors relevant to BMP practices and selection as affected by arid climate conditions, and provides a case study where evaporation rather than discharge was the principle detention facility outlet mechanism. It is intended to contribute to discussions on arid regions hydrology that are currently under way, particularly within ASCE's EWRI Urban Water Resources Research Council, and to stimulate dialogue regarding stormwater management practice in such areas. While BMP solutions seem by definition to have wide extensibility, it is not clear to the authors that BMP solutions are universally effective. Social context and prevailing infrastructure can make accepted practice in BMP technologies in one area inappropriate in another. The case study demonstrates control of discharge totally by evaporation in an arid region where this was preferred, but it is recognized that alternative measures might be preferred in regions where groundwater storage is an option or where evaporative losses are to be avoided. There is already some substance in the literature that reflects this kind of appropriate discrimination of preferred solutions, but there remains a significant need to extend and further develop this understanding.

Select this Article		Meeting the Challenges of Water Scarcity Policy Review and Strategy Formulation D. B. Stacey and Ashraf Elkhadrawy, P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)3 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The current availability of renewable water resources in the MENA region is just above 1000m³ per capita per year, a level that is regarded as representing “water scarcity”. This represents the region as a whole and masks the complex water related issues that face the diverse countries of the region. Specific and well formulated water policies and national water strategies are required if the future demands for water are to be met. These should be assessed in the context of macro‐economic policies and the opportunities that are presented through “virtual water” imports, elements which vary widely across the MENA region. Supply and demand management measures, legal and institutional issues also need careful assessment and integration into water strategies. Some progress is already being made. Black & Veatch, funded by the UK's Department for International Development, have recently completed a research project, on water demand management options and their integration into water policy and water resources strategies and these are also discussed in the paper.

back to top

BIORETENTION AND INFILTRATION ISSUES

Select this Article		Nutrient Retention in Mature Vegetated Bioretention Systems under Elevated Nutrient Loads William C. Lucas, S. M. ASCE and Margaret Greenway ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)4 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract 30 well‐established 240L bioretention mesocosms were used to investigate retention of dissolved nutrients by bioretention systems. 10 mesocosms were comprised of 80cm sandy loam, 10 of 80cm loamy sand, and 10 of pea gravel with 20cm of loamy sand. Half were vegetated with shrubs/grasses, while the other had no vegetation (barren). In our study, the mesocosms were loaded weekly with 45cm of tertiary effluent with high nutrient loads (23.2 m‐yr⁻¹ hydraulic load at a flow‐weighted average of 4.8 mg‐1⁻¹ TP and 4.8 mg‐1⁻¹ TN, or 1,090 kg‐ha⁻¹‐yr⁻¹ TP and 1,093 kg‐ha⁻¹‐yr⁻¹ TN). After 50 weeks of loading, cumulative TP retention was 92% in the vegetated loam, 67% in the sand, and 44% in the vegetated gravel. However. TP retention by barren media was 56% in the loam, 38% in the sand, and 15% in the gravel. Cumulative TN retention was 79% in the vegetated loam, 52% in the sand, and 43% in the vegetated gravel. In contrast, maximum TN removal by barren media was 21% in the loam. The increase in TP retention by vegetated systems substantially exceeds phosphorus uptake rates for plants, suggesting that other processes are involved. The increase in TN retention by vegetated systems also exceeds nitrogen uptake rates for plants, suggesting that denitrification is involved.

Select this Article		Performance Assessment of Low Impact Stormwater Practices B. C. Asleson, R. S. Nestingen, J. S. Gulliver, R. M. Hozalski, and J. L. Nieber ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)5 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract In a time of continuing urban sprawl, using stormwater best management practices (BMPs) to effectively control and treat stormwater remains an important topic. Rain gardens are one such BMP that qualifies as a low impact development. Rain gardens are an aesthetically pleasing option that reduce runoff volume and remove stormwater pollutants through the processes of infiltration/filtration, adsorption, evapotranspiration, and plant uptake. However, before choices can be made, performance specifications and maintenance requirements need to be developed. Monitoring programs are often used to evaluate the performance of stormwater BMPs such as rain gardens. Monitoring a large number of low impact development (LID) practices, however, is impractical due to the time and cost requirements and the large uncertainty in the performance results. It is of interest, therefore, to develop other techniques to determine the effectiveness of these infiltration practices. Infiltration rate is a key assessment parameter for rain gardens. Three additional methods for determining the infiltration rates of rain gardens have been developed as part of a tiered four level assessment protocol. The four levels of assessment in the protocol include: a visual inspection, infiltration capacity testing, stimulated runoff testing, and monitoring. The results can provide useful insight to proper design, operation and maintenance schedules to achieve stormwater treatment goals.

Select this Article		Water Quality and Hydrologic Benefits of Five Bioretention Cells in North Carolina William F. Hunt, Elodie Passeport, and Robert A. Brown ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)6 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Five bioretention cells were studied from 2004 through 2007 in central North Carolina. They were located in Charlotte (1), Graham (2), and Rocky Mount (2). The former three cells were located in the Piedmont and therefore were underlain by clay‐influenced soils. The latter two cells were located in the Upper Coastal Plain, which were sand dominated. The cells differed by vegetation cover, media type, media depth, and underdrain configuration. The Charlotte cell was 1.2 m deep and filled with a sandy‐loam soil. It was drained by conventional underdrains and vegetated by trees and shrubs and covered by mulch. The Graham cells were 0.6 and 0.9 m deep, employed a proprietary soil comprised primarily of expanded slate fines, and had an upturn in the underdrain to create a sump to temporarily store water. The two cells were turf covered. In Rocky Mount, both cells were 0.9 m deep and used a sand fill media (98% sand). Both cells employed an upturned underdrain, but one cell was vegetated by turf grass and the other cell was vegetated by trees and shrubs and covered in mulch. Substantial data have been collected for the cells in Charlotte and Graham, while data collection in Rocky Mount is on‐going. To date, all five cells, despite their many different design elements, have been shown to reduce nutrient loads and concentrations, and reduce outflow volumes, as compared to inflow volumes. Important implications of the research are a continued refinement of bioretention performance standards, confirmation that grassed systems perform comparably well to tree and shrub systems (at least in the short term), and the role of an upturned drainage system, particularly in a somewhat sandy in situ soil.

back to top

BMP PERFORMANCE

Select this Article		Construction Site Stormwater Treatment System Performance Comparison of Coagulation Efficiency Rebecca Mirsky, Ph.D., P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)7 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Chemical coagulation‐flocculation systems are increasingly being used in construction stormwater treatment systems for the clarification of turbid runoff. Numerous coagulants and flocculants are available, but their application to stormwater is relatively recent, and there is little data available allowing a quantitative performance evaluation and comparison. This study presents a laboratory evaluation and comparison of common coagulants used for stormwater treatment. Jar tests were conducted using four different chemical coagulants, with synthetic 1000‐NTU stormwater made up from soil samples from construction sites. Results demonstrate that coagulant performance varies considerably for a given soil, with optimum doses ranging from a few mg/L to over 100 mg/L, and that different coagulants have characteristic dose/response curves.

Select this Article		Nutrient Loading in a Mature Constructed Stormwater Wetland Bridget M. Wadzuk and Robert G. Traver ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)8 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Constructed stormwater wetlands (CSWs) are considered to be an effective part of green infrastructure to improve stormwater quality, however further research is needed to validate the CSWs ability to reduce nutrient loads. Past studies on the Villanova University CSW under baseflow conditions showed Total Nitrogen and Total Phosphorous had approximately 72% and 78% removal efficiency (by concentration) in the fall, respectively. For storm events, the removal efficiency (by concentration) of Total Phosphorous was 38%, but the results for Total Nitrogen were mixed, with a 1% increase in concentration through the CSW. The facility was again under study beginning in summer 2007 to evaluate water quality and quantity of a mature CSW under baseflow and storm conditions. The results confirm the treatment capability of Total Phosphorous under storm and baseflow conditions, and show an improvement in treatment of Total Nitrogen. The present work links discrete storm and baseflow samples to begin to integrate the fate and transport of pollutants to fully validate the nutrient reduction benefits of a CSW.

Select this Article		Weighting of Field Monitoring Data with Probability Distributions of Daily Rainfall James H. Lenhart, P.E. and Scott A. de Ridder ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)9 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Many BMPs undergo field monitoring to assess the ability of the BMP to meet water quality goals. This is typically accomplished using protocols that outline data quality objectives. Some of these objectives include a minimum number of storms, minimum storm depth, and flow rates or water quality volumes that span the operating range of the BMP. Typically during the data analysis, mass weighting is used to calculate performance efficiency on a load basis. However, considerations for the weighting of the storms, relative to the frequency of occurrence is typically not done. This can be problematic in that the collection of too many small storms may not reflect the ability of the BMP to perform for larger storms, or the collection of too many large storms could underestimate the relative performance of the BMP on a long‐term basis. This paper investigates a method to weight the storms collected relative to the frequency distribution of the average annual daily rainfall. This method could be used in the development of sampling protocols and methods currently being established by committee through EWRI.

back to top

BMP PROGRAM ANALYSES

Select this Article		Air Port Water Quality Soars to New Heights Jason Ziemer ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)10 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Seattle‐Tacoma International Airport Third Runway Project in SeaTac, Washington, is one of the largest earth work projects in the country. The entire project is adjacent to sensitive receiving waters including wetlands and salmon‐bearing streams making stormwater quality a top priority. Achieving compliance with the project National Pollutant Discharge Elimination System (NPDES) Stormwater Permit required an integrated stormwater management strategy which included aggressive implementation and maintenance of traditional best management practices (BMPs), installation of large stormwater storage ponds and the use of a relatively new flow‐through water treatment technology termed chitosan‐enhanced sand filtration (CESF). The case study will discuss project details including CESF technology basics, water treatment limitations, summary of water quality data and pollutant removal efficiencies, applicability of CESF technology to other types of construction projects and costs. The success of this project has been recognized by scientist such as Bill Nye, The Science Guy, publishers such as Forester Communications and local television broadcast news (KOMO TV — Seattle, WA).

Select this Article		Hydrological and Environmental Effect Analysis of Penetrable Pavement in Coastal City Xu Shiguo, Gao Jihui, Xu Xiangzhou, and Sun Yong ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)11 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract China is now in her high speed development period of urbanization. However, a lot of problems appear recently that are concerned with the changes of ground surface in urban areas. The flooding and water logging happen frequently while groundwater level falls down. The use of penetrable pavements is one of useful measures to compensate the changes of urbanization. The paper, based on experiment and analysis of penetrable pavement projects in Dalian City, China, discusses the hydrological and environmental effects of penetrable pavement. Dalian belongs to the north seasonal rainfall zone. The most of annual rainfall occurs in the 4 month's rainfall season. Considering these natural conditions, the effect and benefit of penetrable pavement in urban areas is evaluated. The research results are helpful to make the decision how to extend this measurement and how to compensate the additional consumption for using penetrable pavement.

Select this Article		International Stormwater BMP Database: What's in It for You? Jane Clary, Jonathan Jones, P.E., Eric Strecker, P.E., and Marcus Quigley, P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)12 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract More then a decade ago, members of the Environmental and Water Resources Institute's (EWRI's) Urban Water Resources Research Council (UWRRC) identified a need to gather sufficient technical design and performance information to improve urban stormwater Best Management Practice (BMP) selection and design so that local stormwater problems can be cost‐effectively addressed. As a result, the International Stormwater BMP Database Project was initiated. The U.S. Environmental Protection Agency (USEPA) initially funded the project through the UWRRC of ASCE via multiple grants, and in 2004, the project transitioned to a more broadly supported coalition of partners led by the Water Environment Research Foundation (WERF), and including the American Public Works Association (APWA) and the Federal Highway Administration (FHWA), as well as ASCE and USEPA. While the long‐term vision of the project has remained the same, many significant improvements to the database have been made. This paper provides an overview of the overall database project for those unfamiliar with the project and identifies major changes that have been made for those familiar with the early stages of the effort. This paper provides an overview of the resources now available from the www.bmpdatabase.org website. Key aspects of these resources include enhanced tools to track BMP performance through improved data entry spreadsheets and a significantly revised project website. Additionally, an overview of the studies contained in the database, which now includes over 340 BMP studies, is provided. Several examples of how regional and state organizations have adopted the database to track their own BMP performance and improve reporting associated with BMP performance studies are provided. The presentation accompanying this paper will provide additional examples of how the database can be used as a tool for a broad range of entities involved in stormwater management and research or affected by National Pollutant Discharge Elimination System (NPDES) permits, such as public works administrators and engineers, state transportation departments, consulting engineers, and university researchers. Due to significant growth of the database and improvements in data analysis and summary products, the database is a scientifically‐based resource that now offers relevant information and tools to all of these users.

Select this Article		Stormwater BMP Maintenance and Certification Program in North Carolina, USA William G. Lord and William F. Hunt ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)13 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Stormwater practices are being installed across the world and studies show they are not being properly inspected and maintained. If not properly maintained, stormwater practices will not perform as intended, but minimal guidance on maintenance procedures is available. In North Carolina, U.S.A., the North Carolina State University Cooperative Extension Service has developed a 1.5 day training and certification program that has certified approximately 500 design, local government, and landscape maintenance professionals and practitioners in stormwater practice inspection and maintenance. To date the response has been very favorable, as several communities now require the certification for anyone who designs and/or maintains stormwater practices. Officials with the state of North Carolina have incorporated designing for inspection and maintenance as part of their stormwater practice review.

back to top

BMP TREATMENT TECHNOLOGY

Select this Article		Examining the Impact of Detention Basins on Floodplains in Lenexa, Kansas Nate A. Garrett, P.E., Christine A. Pomeroy, Ph.D., P.E., and Tom A. Jacobs, P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)14 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The impacts of stormwater controls within headwater streams are rarely accounted for when Federal Emergency Management Agency floodplains are delineated even though stormwater controls, and specifically detention ponds, are often designed to control peak discharges from 10‐, 25‐ or 100‐year runoff events. Inconsistency in the maintenance of stormwater controls impacts their reliability for control of peak discharges, but it is hypothesized that if these facilities are properly and consistently maintained, their impacts on floodplains should be considered in their delineation. The City of Lenexa, Kansas is currently undergoing a study to develop a strategy for maintaining and improving existing detention facilities with the goal of refining floodplain boundaries, providing long‐term stream stability, and improving water quality. As part of this project, an assessment was conducted to inventory existing detention basins within the study area by reviewing aerial/topographic mapping and as‐built information combined with a field reconnaissance. It was found that a significantly greater number of basins existed within the study area than was originally anticipated. The impacts of the detention basins were evaluated using HEC‐HMS and HEC‐RAS models to better understand the function and necessity of the existing facilities, to determine the level of service of the existing basins and to determine their combined impacts on receiving streams from both a flooding standpoint and a geomorphologic standpoint. For the hydrologic analysis, an existing HEC‐1 model was converted to a HEC‐HMS model, and then modified to provide storage nodes that reflect the existing detention ponds. For the hydraulic analysis, HEC‐RAS models were used to simulate the 2, 10, and 100‐year design storms using the peak flow rates estimated by the HEC‐HMS model. These analyses will be used to create a detention basin strategy that maximizes flood reduction potential for the 10 and 100‐year design storms through improved maintenance of existing detention basins, retrofitting of existing basins, and the identification of locations that would be beneficial for new detention basins.

Select this Article		Monitoring of Pervious Pavement/Infiltration Bed System in Aurora, Colorado T. Andrew Earles, Ph.D., P.E., Jennifer Keyes, and Michael Claffey, Jr. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)15 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract This paper presents the monitoring results of infiltration‐based stormwater best management practices (BMPs) for a commercial development site in Aurora, Colorado. Although the Denver Urban Drainage and Flood Control District (UDFCD) has criteria for pervious pavement and for infiltration‐based BMPs, these practices have not been widely used in the Denver Metropolitan Area, and very little monitoring data have been collected to evaluate the effectiveness of such practices. The site evaluated by the study described in this paper is a 9.35‐acre parking area for a commercial retailer. The parking area consists of sections of pervious asphalt and pervious concrete pavement underlain by gravel infiltration beds as well as areas of traditional pavement which drain to bioswales. The bioswales are connected to the infiltration beds beneath the pervious pavement sections. Through a series of perforated pipes, monitoring of the site began in the spring of 2006, and over a two‐year period, fourteen events have been captured. Monitoring has been conducted using automatic stormwater sampling equipment for collection of water quality samples from the bioswales and using Barologger level measurement devices to evaluate infiltration bed hydrology. Nine groundwater monitoring wells were installed to evaluate the effects of the infiltration‐based BMPs on groundwater. Water quality samples and level measurements collected from wells have yielded groundwater quantity and quality data that complement the monitoring data from the bioswales and infiltration beds. Results of groundwater monitoring will be discussed in a forthcoming, separate paper due to space constraints of conference proceedings. This paper focuses on surface water hydrology and quality. Monitoring is scheduled to continue for a third year, and additional monitoring in the future (10 to 15 years) could be extremely valuable for evaluating performance of the system over time.

back to top

CERTIFICATION OF MANUFACTURED DEVICES

Select this Article		Data Reporting Guidelines for Certification of Manufactured Stormwater BMPs Robert M. Roseen, M. ASCE, Ernie Carrasco, Yuan Cheng, Bill Hunt, Charlene Johnston, Jim Mailloux, Walt Stein, and Tim Williams ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)16 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract With the increasing need for the independent field testing of proprietary devices comes the importance of consistent data reporting guidelines to be used when reporting to regulatory agencies. The need for standardized reporting is underscored by the tremendous impact the range of factors can have upon testing results. These factors include the testing environment, experimental design, testing methodologies, statistical analysis, and data presentation. The need for the consistency is underscored by the complex influence these factors have upon performance results. A clear and consistent data reporting approach can ensure that these biases are minimized, well understood, and that representative field testing can be effectively evaluated by the regulatory agency. Data Reporting guidelines presented here were developed as part of the ASCE/EWRI Committee on Guidelines for Certification of Manufactured Stormwater BMPs.

Select this Article		Development of Certification Guidelines for Manufactured Stormwater BMPs Qizhong Guo, Gordon England, and Charlene E. Johnston ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)17 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Manufactured stormwater Best Management Practices (BMPs) are becoming an integral part of stormwater infrastructure, as well as a component of wet‐weather flow technology. They are commonly used but there are few guidelines regarding the use of these manufactured devices. An ASCE/EWRI task committee was formed in May 2007 to develop guidelines for the certification of manufactured stormwater BMPs. The committee kickoff meeting was held at the EWRI 2007 Congress in Tampa, Florida. At this meeting, the scope of work was discussed, with the consensus being to focus on physical separation of particles for the full spectrum of stormwater‐borne non‐dissolved solids. Complex issues regarding testing and certification BMPs were identified, and six subcommittees were formed to address these issues simultaneously. These six subcommittees are: (1) Laboratory Testing, (2) Field Monitoring, (3) Scaling, (4) Data Evaluation, (5) Data Reporting, and (6) Maintenance. This paper provides the results of the Task Committee work to date (January 2008), including review of the existing test, verification, and certification procedures and protocols and identification of additional standards development.

Select this Article		Field Verification of Manufactured BMPs Subject to Rainfall‐Runoff Loadings John Sansalone ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)18 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Field‐testing of unit operations and processes (nominally called BMPs) requires critical planning and implementation through all steps of the verification process from initial watershed selection through defensible statements of BMP behavior based on field verification results. The desired goals and outcomes must be known and designed into the entire verification process. A continual evaluation, quality assurance and feedback protocol must be part of the testing protocol. What are the basic component categories of a well‐designed and defensible field‐testing protocol? In general, while watershed processes can be categorized and modeled, each watershed is different and unique with respect to BMP loadings of hydrologic, chemical, biological and particulate matter (PM) quantities. We must recognize these challenges and collect sufficient representative data so that the role of such uniqueness can be quantified for the specific BMP or BMPs tested. These challenges are significant because at this time there are very disparate methodologies of PM protocols mat range from gravimetric index tests such as the traditional total suspended solids (TSS) method adopted from wastewater treatment evaluations, or the more recent suspended sediment concentration (SSC) method, index tests such as turbidity testing, to more fundamental methods of particle size distributions (PSDs). Each index method provides an indication of BMP performance with respect to PM; however a more fundamental, transferable and defensible methodology includes PSD and turbidity testing that is combined with a representative gravimetric index test for PM. The committee is envisioning developing a multi‐tiered approach to field testing predicated on the intended utilization and rigor required for the defensible and transferable application of BMP performance results. This committee is focused on manufactured BMP separation of PM. It should be recognized that the entire gradation of PM should be representatively characterized for a BMP, in particular the suspended fraction because of the mobility and acute bio‐availability of this finer fraction.

Select this Article		Inspection and Maintenance Guidance for Manufactured BMPs William F. Hunt, Gordon England, Hans DeBruijn, Richard Gee, Qizhong (George) Guo, William Lord, Mark Miller, Omid Mosheni, and Scott Perry ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)19 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract ASCE/EWRI has assembled a Task Committee on guidelines for certification of manufactured stormwater BMPs. A nine‐member subcommittee for maintenance was tasked by the larger committee to develop maintenance guidelines for manufactured stormwater BMPs. The subcommittee has developed recommendations for manufactured BMP maintenance in the following seven areas: (1) designing for maintenance, (2) defining standard maintenance triggers, (3) defining maintenance fundamentals for all manufactured BMPs, (4) defining maintenance tasks by BMP design; hydrodynamic or filter design, (5) identifying entities best able to maintain manufactured BMPs, and training requirements, (6) identifying entities to train maintenance providers, and (7) reviewing recommended disposal techniques for captured pollutants.

Select this Article		Scaling Relations for Manufactured Stormwater BMPs John S. Gulliver, Qizhong Guo, and Jy S. Wu ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)20 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Manufactured stormwater best management practices (BMPs) generally apply one or both of two unit operations to remove particles from stormwater runoff: hydrodynamic separation and filtration. Hydrodynamic separation is best used to remove sand particles, while filtration is used to remove organic particles as well as silt and clay. Many manufactured stormwater BMPs also have a chamber designed to remove floatables, or particles that are lighter than water. The numerous designs and multiple sizes of these manufactured stormwater BMPs suggest the need for scaling criteria to size and apply designs in the field. This paper reviews the scaling criteria research that has been completed, the research that may be adopted from other areas, and the needs for developing scaling criteria in manufactured stormwater BMPs.

back to top

CSO/SSO (MAINTENANCE, DESIGN, COSTS, BLENDING, RTC)

Select this Article		Developing an Optimal Sewer Layout Model to Reduce Peak Outflows J. H. Kim, J. H. Lee, J. H. Park, and H. D. Jun ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)21 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract In sewer layout design, most developed models are designed to determine pipe diameter, slope and overall layout to minimize the least cost for the design rainfall. However, these models cannot consider the superposition effect of runoff hydrographs entering each junction. The suggested Optimal Sewer Layout Model (OSLM) is designed to control flows and distribute the node inflows while taking into consideration the superposition effect for reducing the inundation risk from the sewer pipes. The suggested model used the genetic algorithm to determine the optimal layout, which was connected to the SWMM (Storm Water Management Model) for the hydraulic analysis. The suggested model was applied to an actual urban watershed in Seoul, Korea. By using the suggested model, the peak outflows at the outlet were decreased by approximately 20% than those of the current sewer layout for the design rainfall during 30 minutes.

Select this Article		Emerging Implications of Systematic Balancing of Disinfection and Primary Treatment as an Element of US Practice and Policy in CSO Control: 1. Model Requirements A. C. Rowney, R. Field, and Thomas P. O'Connor ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)22 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract This paper describes early results and directions arising from ongoing research into factors that affect the preferred balance between primary treatment and disinfection in a conventional wastewater treatment plant during periods of wet weather overflow. Despite the fact that national policy and regional regulations have required or implied use of these elements of treatment for decades, there remain some basic issues that are unresolved. In the context of a wet weather overflow event, the selection of an optimum point and manner for disinfection as it relates to the degree solids removal is one such issue. The factors that affect the choice of this point, particularly as reflected by the current state of microbiological understanding of quantification methods and of the influences of water chemistry on disinfectant behavior and indicator bacteria partitioning between solid and liquid phase components of the flow stream, are examined. Potential avenues for improved treatment practices are noted, and research directions are discussed.

Select this Article		Satellite Sewer System Modeling Daniel H. Lau, P.E., Debra Jensen, and Robert W. Carr, P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)23 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The Milwaukee Metropolitan Sewerage District (MMSD) provides wastewater and flood management services for 28 municipalities (Figure 1 on the following page) within its 411‐square‐mile planning area. One of the challenges faced by MMSD was the need to understand the timing and volume of flow contributed by each of these municipalities through their local sewer systems to the MMSD's Metropolitan Interceptor Sewer (MIS). The MIS is the regional sanitary sewer system operated by MMSD that connects local municipal sanitary sewer systems to the two regional wastewater treatment plants and regional Inline Storage System servicing the Milwaukee metropolitan area. In 2004, MMSD began development of limited satellite municipality System Evaluation and Capacity Assurance Plans (SECAP) for each of the satellite municipalities it serves. The SECAP hydraulic evaluations were limited in that only those portions of the local sanitary sewer systems necessary to provide required information for the 2020 Facilities Plan project were analyzed. The 2020 Facilities Plan is the most recent generation of facilities planning undertaken by MMSD to determine what MMSD facilities are required to meet the needs of the region through the year 2020. Specifically, the SECAP project was to: 1 Identify satellite municipality system capacity deficiencies. 2 Estimate satellite municipality system bypass volumes and flow rates for selected wet weather events. 3 Summarize peak flows delivered to the MIS system for a selection of wet weather events.

Select this Article		SSOAP — A USEPA Toolbox for SSO Analysis and Control Planning Srinivas Vallabhaneni, Fu‐hsiung Lai, Carl Chan, Edward H. Burgess, and Richard Field ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)24 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The United States Environmental Protection Agency (USEPA) has identified a need to use proven methodologies to develop computer tools that help communities properly characterize rainfall‐derived infiltration and inflow (RDII) into sanitary sewer systems and develop sanitary sewer overflow (SSO) control plans. To accomplish this goal, the USEPA entered into a cooperative research and development agreement (CRADA) in 2003 with a technology partner — Camp Dresser & McKee (CDM) Inc. — to develop a public‐domain Sanitary Sewer Overflow Analysis and Planning (SSOAP) Toolbox. The CRADA also prepared a technical guide for analyzing RDII, performing capacity analyses of sanitary sewer systems, and developing SSO control plans using the toolbox. This paper describes the CRADA outcomes and individual tools in the SSOAP Toolbox to perform capacity analyses of sanitary sewer systems and develop SSO control plans.

back to top

INTEGRATED WATERSHED MANAGEMENT AND MASTER PLANNING

Select this Article		Hawaii DOT's Comprehensive Stormwater Asset Management System: A Critical Tool to meet NPDES Permitting Goals K. E. Brennan, P.E., M. ASCE, C. Y. Lien, P.E., M. ASCE, B. Reed, and R. Adams ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)25 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract With the implementation of Phase I and Phase II NPDES permits, many state DOT's have MS4 permits that require the mapping of the DOT‐owned storm drain network as well as implementation of best management practices (BMPs) to fulfill six minimum control measures including public education and outreach, public participation and involvement, illicit discharge detection and elimination, construction site stormwater runoff control, post construction stormwater management in new development and redevelopment, and pollution prevention/good housekeeping measures. As partial fulfillment of the Island of Oahu's MS4 NPDES Permit (No. HI S000001), the State of Hawaii Department of Transportation, Highways Division (DOT‐Hwys) has developed an Asset Management System (AMS) to provide program staff with tools for the efficient and effective management of information generated by the components of the Statewide Storm Water Management Program (SSWMP). The AMS is capable of housing and organizing vast amounts of data, providing the means for program staff to analyze this data through computerized processes and solutions. AMS will provide the following support to the Oahu SSWMP. This paper will document the challenges and successes that HDOT has had in the development and implementation of a comprehensive, web based asset management, system.

Select this Article		Water Portfolio Scenario Analysis for Mesa, Arizona T. Lant, G. Yamout, and V. Escobar ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)26 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract This paper presents a prototype decision support system (DSS) that can be used to analyze municipal water portfolios using science‐based climate models and regional scale urbanization scenarios. We present a system dynamics (SD) DSS, loosely coupled with a geographic information system (GIS) for water portfolio scenario analysis for Mesa, Arizona. The application demonstrates a multi‐scale, modular, spatial framework for downscaling a regional dynamic water budget to the specific water portfolio of the City of Mesa. Climate change, population growth, surface water allocations, and groundwater supplies are calculated from WaterSim, a regional DSS developed at the Decision Center for a Desert City at Arizona State University; Mesa's specific water portfolios are generated via a portfolio module that extends the WaterSim framework to include city‐scale demands, conservation estimates, “water‐banking” credits, and multi‐institutional constraints. The portfolio module connects a regional supply module to local and regional demand modules so that meaningful, scenario‐based exploration of the city's water assets can be examined for adequacy and risk of shortages. In particular, conditions of drought, climate change, population growth, urbanization, and land‐use change are simulated to reveal robust portfolio allocations that can better guarantee adequate water supplies with low cost and low risk of shortage under a broad range of conditions. Our scenario framework classifies scenario models into exogenous factors, policy options, and outcome metrics to systematically assess the key sensitivities of Mesa's water supply portfolio.

back to top

LID DESIGN, PERFORMANCE, AND REUSE

Select this Article		Management of Dry Weather Flows in Semi Arid Climates Using Low Impact Development Technology Aditya Tyagi, Barbara Chongtoua, Daniel Medina, Avinash Patwardhan, and Cole Slater ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)27 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Urbanized semi‐arid regions experience a significant amount of dry‐weather flows in the form of return from excessive irrigation on suburban lawns. These dry‐weather flows also carry significant amounts of nutrients from household fertilizers, which are discharged to receiving water bodies. These nutrients cause unsightly algal growth sometimes known as “urban slobber,” that result in oxygen depletion due to organic matter decay. These flow rates can constitute a large component of dry‐weather flow in urban streams. The conditions of semi‐arid climates are conducive to turn these flows into a more visible nuisance than in humid regions. This paper explores the application of LID technology to manage dry‐weather flows in semi‐arid climates. LID's infiltration‐based controls can be deployed to intercept and treat nutrient‐laden excess irrigation flow. The concept is illustrated in a subdivision in Los Angeles, California area by applying the LIFE™ model developed by CH2M HILL for simulation of LID hydrology.

Select this Article		Meeting Challenges of Stormwater Management in Semi Arid Climates with Low Impact Development Aditya Tyagi, Barbara Chongtoua, and Daniel Medina ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)28 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The Low Impact Development (LID) techniques have been found to be advantageous in mimicking the pre‐development hydrologic regime of urban and developing watersheds by attempting to preserve or restore the components hydrologic cycle. LID applications are common in humid climates in the northwest, mid‐west and eastern portions of the United States but have been limited in the semi‐arid climates of southwestern states due to some hydrologic issues. In this paper, a thorough evaluation of alternative approaches to stormwater management has been conducted using CH2M HILL's LIFE™ model for a case study in California. This case study provides a brief summary of the results of the LID application and outlines considerations for implementing strategies to reduce the effects of development tand a better understanding of the benefits of implementing LID techniques to minimize the effects of development on stormwater pollution, stream bank erosion, and habitat degradation.

Select this Article		New Directions in Real‐Time and Dynamic Control for Stormwater Management and Low Impact Development Marcus Quigley, P.E., Sri Rangarajan, Ph.D. P.E., Daniel Pankani, P.E., and Dawn Henning ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)29 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Although the application of real‐time and dynamic controls is commonplace in wastewater and combined sewer system management, the use of on‐site dynamic control systems for stormwater has been limited. The availability of low cost, highly functional, internet accessible, programmable logic controller systems and single board computer platforms and a new breed of large diameter, lower cost, low maintenance valve systems are making real‐time and dynamic controls viable options for both new construction as well as retrofits of stormwater systems. The inclusion of dynamic control systems in on‐site stormwater systems provides designers with an effective tool for meeting increasingly complex stormwater suite of goals by retaining water as close as possible to where it is generated and releasing it over an extended period to minimize the potential effects from stream ecological and morphological perspectives. Typical stormwater analysis and modeling is focused on developing designs that passively achieve stated goals; however, passive systems rarely represent optimal solutions. Dynamic systems are particularly well suited for complex situations where timing, duration of flow, peak discharge, volume reduction and reuse, and water quality are critically important. This paper focuses on describing the state‐of‐the practice, recent research by the authors, and new directions in applications, design, and equipment. Innovative applications that will be described include integration into low impact designs, flow‐duration control, integration of embedded stormwater models, adaptive management approaches, water quality treatment optimization, and reuse. Case studies where such implementations have been explored as discussed.

Select this Article		Water Reuse on Maui Steve Parabicoli ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)30 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The County of Maui's Wastewater Reclamation Division (WWRD) is recognized as a water reuse leader in the State of Hawaii. This paper will track the development of the WWRD's water reuse program from the early 1990's to its current status of playing an important role in sustainable water resource management in Maui County. The objectives of Maui's water reuse program are to supplement Maui's limited potable water supply and to reduce the use of injection wells for effluent disposal. Recycled water is reused from all five of the County's wastewater reclamation facilities and significant distribution systems have been constructed in south and west Maui. Recycled water is now used for a wide variety of purposes including landscape irrigation, agricultural irrigation, cooling, fire control, composting, toilet flushing, environmental enhancement and construction purposes. The initial primary factor driving Maui's water reuse program was a concern that the use of injection wells for effluent disposal was the main cause of periodic seaweed blooms that occur in Maui's coastal waters. While this concern still lingers, increased development and the lack of available fresh water have shifted the primary driving factor to more of a water supply issue. Recycled water is now considered an extremely valuable resource in Maui County and as a result, developers are funding expansions to Maui County's recycled water distribution systems. These expansions will benefit Maui's community and environment through potable water savings and the reduction in the use of injection wells for effluent disposal.

back to top

PATHOGENS AND INDICATOR ORGANISMS IN STORMWATER

Select this Article		Column Studies on the Capture and Destruction of E. coli from Simulated Urban Stormwater Runoff Using Conventional Bioretention Media and Iron Oxide‐Coated Sand Lan Zhang, Eric A. Seagren, and Allen P. Davis ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)31 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Given the magnitude of the threat to water quality posed by microbial pollutants in urban stormwater runoff and the untested potential for their removal in bioretention systems, the objectives of this research are to evaluate the capture and destruction of E. coli O157:H7 strain B6914 (as a pathogenic indicator) from synthetic urban stormwater runoff by conventional bioretention media, and to examine the potential of iron oxide‐coated sand (IOCS) for enhancing bacterial removal. The results of these column experiments indicate that conventional bioretention media achieved approximately 80% removal of E. coli under the test conditions. Coated iron oxides enhanced bacterial adsorption through surface charge modification, increasing bacterial removal to 99%. However, the die‐off rate of trapped cells in conventional bioretention media was far quicker than in the IOCS as studied. More than 99.98% of B6914 cells attached to conventional bioretention media died off within one week. Therefore, conventional bioretention media have a greater potential to render the process sustainable.

Select this Article		E. coli Fate and Transport in Macroporous Soils: Short‐Circuiting to the Subsurface G. A. Fox, Ph.D., P.E., A. M. ASCE, R. Kanwar, Ph.D., J. Guzman, C. K. Hoang, R. W. Malone, Ph.D., T. Moorman, Ph.D., and C. Pederson ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)32 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Pathogen concentrations in streamflow are commonly reported as a significant cause of water quality degradation throughout the world. Research has begun to attempt to model pathogen fate and transport, primarily through surface runoff mechanisms. A significant component of pathogen movement to streams commonly identified but not explicitly simulated in many models is pathogen movement to the subsurface, which can be important in several scenarios such as tile drainage systems. As colloidal contaminants, pathogens such as E. coli tend to become physically trapped in the soil matrix but can move quickly through soil macropores. In fact, concerns exist about the rapid transport of contaminants, such as pesticides, pathogens, and nutrients, from the soil surface to ground water through macropores. Recent research suggests short‐circuiting or direct hydrologic connectivity between macropores and subsurface drains. The objective of this paper is to provide an overview of the current research regarding the fate and transport of E. coli through soil macropores and into subsurface drain systems. This paper reports early results from the first year of a multi‐year study funded by the USDA Cooperative State Research, Education, and Extension Service as part of the their National Research Initiative program. Field experiments to document short‐circuiting by macropores are described and also laboratory data is presented from soil column experiments, capable of simulating surface‐connected macropores, with artificial subsurface drainage boundary conditions. These column studies generated information regarding the importance of directly connected macropores on pathogen transport to subsurface drains.

Select this Article		Enterococci Populations in Conventional, Manufactured and LID Stormwater Treatment Systems Stephen H. Jones, Robert Roseen, Robert A. Wildey, Julie Maimes, James Houle, and Thomas Ballestero ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)33 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Pathogenic microoganisms can cause disease in humans exposed to contaminated recreational waters. New Hampshire uses enterococci as the fecal indicator in estuarine and marine recreational waters. Stormwater runoff is the most significant source of bacterial pollution in NH, and several types of routinely installed stormwater control systems are ineffective for removing enteroocci. This study addresses the performance of eleven treatment system designs on enterococci populations during storms. Water samples were collected during storms from eleven treatment systems under controlled conditions and enterococci were enumerated using EPA method 1101.6. Some systems appeared to be sources while others appeared to remove enterococci from runoff. Enterococci concentrations exhibited marked seasonal trends, peaking in August. These results suggest elevated enterococci concentrations are present in wet treatment systems between storms, resulting in increased concentrations being discharged into receiving waters with runoff from storms. Ongoing studies are designed to better characterize enterococci dynamics between storm events.

Select this Article		Reducing Stormwater Bacteria Loads to North Carolina Ocean Recreational Areas Using a Dune Infiltration System M. R. Burchell, W. F. Hunt, III, and G. M. Chescheir ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)34 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Coastal towns traditionally discharge stormwater containing bacteria and pathogens to the ocean via ocean outfalls, increasing the potential for serious diseases to recreational swimmers. To combat this risk, an innovative coastal BMP, a Dune Infiltration System (DIS), was designed and installed at two locations in Kure Beach, N.C. to divert stormwater from outfalls into the dunes. Post‐construction monitoring of these systems during 25 storm events in 2006 showed that this design was economically and technically feasible, because 97% of the stormwater was diverted into the dunes, the dunes remained structurally stable, and Enterococcus concentrations entering from the outfalls were reduced by over 97%. However bacterial transport surrounding the system remained poorly understood, which limited the certainty at which this system could be recommended for further implementation. Therefore, a series of additional water table and water quality wells were installed at each of the systems, and in a nearby control dune, during the summer of 2007. After six‐months, bacterial concentrations in the groundwater at the dune‐beach interface near the dune infiltration sites are similar to that of the control area.

back to top

POSTER SESSION III: 5TH URBAN WATERSHED SYMPOSIUM

Select this Article		An Integrated Modeling Approach to Stormwater Management Sri Rangarajan, Ph.D., P.E., Masatsugu Takamatsu, Gary Grey, and Win Hunt ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)35 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract An integrated XP‐SWMM and TUFLOW modeling framework was used to simulate flood propagation and evaluate the effectiveness of flood mitigation scenarios for the James Madison University (JMU) campus which had experienced frequent flooding historically. A flood mitigation scenario was developed as a combination of new relief pipe system to divert runoff from the off‐campus drainage areas and an enhanced drainage system near the campus' outlet point. The developed flood mitigation scenario was simulated to evaluate its effectiveness. The simulated maximum flood depths for this scenario showed significantly decreased flood propagation and accumulation. The 2D visual interface for flood propagation comparison was very effective in terms of communicating the flooding consequences at critical flooding locations to the campus stakeholders.

Select this Article		EPA's Experimental Stream Facility: Design and Research Supporting Watershed Management Christopher T. Nietch, Ph.D. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)36 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The EPA's Experimental Stream Facility (ESF) represents an important tool in research that is underway to further understanding of the relative importance of stream ecosystems and the services they provide for effective watershed management. The ESF is operated under the goal of supporting the integration of risk assessment and management research objectives for water quality protection with controlled studies designed to characterize how streams react to and process emerging contaminants and stressful mixtures. The engineering aspects of the ESF set‐up are described that allow for a balance between controlled laboratory conditions and the natural variability that is inherent to stream ecosystems, and that are required for adequate ecological simulation. Flow distribution is configured so that real stream water is delivered to eight mesocosms allowing for natural and optimal colonization while controlling for water residence time and hydraulic properties of riffle microhabitat. Single contaminants or stressful mixtures can be precisely dosed. Characteristics such as light intensity, influent water quality, and streambed substrate type can be manipulated within and across studies. Each ESF study provides information on ecosystem structure and function that can be used in relation to the development and testing of new indicators of ecological stress, water quality monitoring technologies, and water quality management methods and models.

Select this Article		Green Roofs — A BMP for Urban Stormwater Quality? Brett V. Long, A. M. ASCE, Shirley E. Clark, M. ASCE, Ph.D., P.E., Robert Berghage, and Katherine Baker, Ph.D. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)37 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The focus of this research is the impact of green roofs on urban stormwater quality and builds on a laboratory study that evaluated several potential green roof media to produce a mix that produced the “best” overall reduction in pollutants from simulated rainwater. Because of the limitations of the laboratory testing, this second phase (field test) was performed. A second purpose was to determine if this actual media mix would support plant life with minimal maintenance. The third question raised by the researchers was whether the green roof, at the low concentrations often seen in many pollutants in wet and dry deposition, could remove these pollutants. If not, was the green roof at least “chemically neutral” (e.g., did not remove or add pollutants to the runoff, such as those added to rainwater by passage over a galvanized metal roof?) The field study showed that, during the early life of these roofs, water quality from the green roofs was comparable to the control roofs and better, with the exception of phosphorus and added color, to that of the galvanized roof. The increase is color is believed to be from washout of the organics in the media. Plant development on these roofs has been very slow, probably due to the lack of added fertilizers and minimal organic matter; however, the water quality benefits may substantially outweigh the need for rapid plant growth.

Select this Article		Incentives for Adoption of Low Impact Development Approaches on a Larger Scale Scott D. Struck, Ph.D., A. M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)38 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract On‐site integrated water management has become one of the critical elements for protecting our water and treating it as a useful resource. Water conservation, capture, and reuse can help maintain a supply of water for current and future water needs. Preventing excessive quantities of runoff while maintaining the quality of surface waters can reduce or, in some cases, eliminate pollution from entering our natural drainage areas and limit hydromodification thereby protecting the ecological functioning of our natural receiving waters (rivers, streams, lakes, and wetlands). Despite the current regulatory environment, there are inconsistencies in the ability to successfully implement on‐site integrated water management. Reasons for this include the necessity for regulators to approve new approaches (e.g., new road standards, site clustering), a change in designs standards, consideration of whole‐life cycle cost, permit reviewers must have proper training and approved procedures, and the public must become more educated in stormwater management. While it is hoped that developers will recognize the validity and marketability of integrated water management, one of the largest impediments to implementation is the lack of incentives to encourage developers and builders to use integrated water management techniques. It is necessary to focus research on tools that lead to the successful adoption of on‐site integrated water management, in particular methods that may condition and encourage public, developer, and builder acceptances of this approach. A watershed sustainability index based on holistic water management strategies that provide a framework for evaluation and a transparent rating system for new and redevelopment projects would be developed in this research effort. The watershed index, created through an expert panel, would define a set of standards and apply a numerical “credit” method measuring the degree to which the standards are met. The standards would be based on low impact development techniques such as integrated site design and decentralized stormwater controls that value greater flow attenuation, larger runoff volume reductions, and extended runoff duration while also minimizing the generation and transport of stormwater pollutants. The index would use an independent, third‐party verification process to “score” a development's design and build based on on‐site integrated water management and incorporation of multiple benefit techniques. Watershed managers, regulators, and developers would be able to estimate the number of credits earned as a measure of effort to minimize land development impacts on hydrology and water quality.

Select this Article		Modeling LID Treatment Train Impacts on Runoff, Sediment, and Water Quality in U.S. Urban Areas Using IDEAL: Part 2 — Model Application to Example US Cities J. C. Hayes, B. J. Barfield, S. L. Harp, M. Chalavadi, E. Stevens, M. D. Alexander, and B. T. Bates ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)39 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Part 2 of this two part series is an application of IDEAL, an object based post construction hydrology model, to water quality prediction that is suitable for use in cities throughout the US. Example prediction is made of the impact of selected LID concepts and treatment train Best Management Practices (BMPs) for Greenville, SC for which the model was developed. Additional applications are shown based on conditions for Albany, NY; Austin, TX, Baltimore, MD; Honolulu, HI, Salem, OR; Tallahassee, FL and Tulsa, OK. Local rainfall and soils information is used in the model predictions. Comparisons of sediment and nutrient loadings are made for multiple suites of treatment trains as well as for conditions having no BMPs. The results of this modeling effort are intended to show how varying climates and soils impact the effectiveness of varying treatment trains. Low Impact Development (LID) concepts and BMPs modeled by IDEAL include disconnecting storm drains, use of water barrels, bioretention cells, bioswales, sand filters, and VFS. Comparison can be made between the use of LID concepts and BMPs with the more traditional wet and dry ponds.

Select this Article		Modeling LID Treatment Train Impacts on Runoff, Sediment, and Water Quality in US Urban Areas Using IDEAL: Part 1 — Model Description Billy J. Barfield, John C. Hayes, Sam Harp, Mahesh Chalavadi, Sandeep Yeri, and Brian Bates ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)40 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Part 1 of this two part series is an overview of IDEAL, an object based program developed in Microsoft® Visual Studio.Net to predict the runoff and pollutant loadings in urban post construction watersheds. IDEAL has the capability of predicting distributed source area generation of runoff, sediment, nutrients, and pathogens in post construction watersheds and route those through channels and structural BMPs. Procedures are also available to apply the model to the urban fringe with construction and agricultural source areas as well. The user interface uses a graphic user interface (GUI) with drop and drag capability to generate large numbers of subwatershed source areas, conveyances, and BMPs arranged in treatment trains. The limit on numbers and sizes of subwatersheds that can be used is primarily computational time and appropriateness of the conveyance objects. BMPs are modeled with process based algorithms that take into account mass continuity and the processes of infiltration, settling, and sorption for chemicals and pathogens as well as mortality and growth for pathogens. Deposition of human and wildlife source pathogens on BMPs is also calculated. Using probabilities of rainfall amounts, seasons, and infiltration characteristics, annual averages are computed for loadings at any point on the watershed. Interarrival time of storms is also used as a factor. An example model computation is given.

Select this Article		Rainfall Intensity in Design Theodore G. Cleveland and David B. Thompson ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)41 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract An empirical, dimensionless‐hyetograph that relates depth and duration, and thus whether a storm is front loaded, back loaded, or uniformly loaded, based on 92 gaging stations for storms known to have produced runoff is available for Texas. Statistical characteristics of storm interevent time, depth, and duration, based on analysis of hourly rainfall data for 533 rain gages are used to “dimensionalize” this hyetograph and produce a set of simulated storms. These simulated storms are analyzed to generate a set of rainfall intensities, and these intensities are compared to global maximum observed rainfalls, intensities estimated using the National Weather Service TP‐40, and HY‐35 publications, and a current Texas Department of Transportation design equation. The simulated storms agree well with the other methods for rare (i.e. 90‐th percentile and above) occurances and lie within the global maxima envelope. The simulated results are quite different for common (i.e. 50‐th percentile) events.

back to top

SEDIMENT AND EROSION CONTROL

Select this Article		Comparison of Compost and Hydromulch for Stabilization of Disturbed Sites Michael Barrett, Anne McFarland, Brad Eck, and Todd Adams ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)42 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Construction projects often expose large amounts of soil to the erosive forces of wind and rain. These areas must be stabilized and vegetation established before a Notice of Termination can be submitted to regulators. Quarries face many of the same issues with regard to stabilization of spoil piles and areas disturbed by mining. The objectives of this project were to compare the stabilization performance of two types of compost top dressing (low and high organic matter), a wood based hydromulch, and seeded bare soil and to determine the amount of sediment and nutrients exported from each type of treatment. Ten test plots (8 feet × 40 feet) were constructed on a spoil pile of a quarry located in Parker County, Texas. These plots were outfitted with runoff capture systems to collect all runoff from each plot. Water quality and quantity data were collected for 10 storms during the first year after installation. Compost mixtures were most successful at establishing vegetation, with almost full coverage after about four months. The hydromulch plots took much longer, with full establishment taking almost a year. The seeded bare soil plots had little vegetation even after a year. Runoff coefficients for the two types of compost were similar and about half that observed for the hydromulch and control plots, which were not significantly different. Compost reduced sediment discharge compared to bare plots by about 97%. The hydromulch was less effective than the compost treatments, but still reduced the TSS load by about 75% compared to bare plots. Even though both treatments reduced the load of total phosphorus discharged, dissolved phosphorus loads from compost treated plots were higher than from bare soil or hydromulch plots.

Select this Article		SEDPRO Modeling of BMP Effectiveness at Construction Sites S. L. Harp, B. J. Barfield, J. C. Hayes, S. Yeri, and M. Chalavadi ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)43 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract An overview of SEDPRO is given and used to illustrate impacts of changing land use on the environment during urban development. Its use is illustrated for selected watersheds within a rapidly developing area (Greenville County, SC, USA) Basic concepts and development of this innovative model are described to provide an understanding of the approach and limitations. Enhancements over the widely distributed SEDIMOT II and SEDIMOT III models include a graphical interface that features drag and drop placement of subwatersheds, best management practices (BMPs), and conveyances. This feature allows the user to place BMPs at points throughout the watershed and evaluate trapping efficiency of individual BMPs as well as the entire treatment train. Additional BMPs included are sand filters, bioswales, and engineered devices. It also can be used on any order watershed, not just the 3^rd order allowed in SEDIMOT. SEDPRO is used in the paper to illustrating the impact of alternative land uses and different types of construction.

back to top

STORMWATER SOLIDS

Select this Article		Errors Associated with Solids Analysis Christina Y. S. Siu, Shirley E. Clark, Ph.D, P.E., M. ASCE, and Robert Pitt, Ph.D, P.E., M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)44 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Stormwater sampling by automatic samplers and the comparability of the suspended sediment concentration (SSC) and total suspended solids (TSS) methodologies have been a source of debate. Questions include whether autosamplers can pull up the larger, heavier particles found in stormwater, if automatic sampling has a particle size distribution (PSD) range limitation, and whether TSS and SSC recoveries are comparable. This research examined the protocols, limitations, and associated errors for solids determination. The autosampler was examined for its ability to sample simulated stormwater repeatably and accurately at various elevations above the water surface and within the water column, including the effect of PSD at all heights. Sample processing and splitting by churn and cone splitters were investigated for accuracy and repeatability in obtaining subaliquot volumes and representative PSD. Finally, two TSS methods and SSC were examined for recovering a known concentration and the comparability of the inter‐ and intra‐ methodologies.

Select this Article		How Well Do We Know “Particle Size” in Urban Runoff Pollution Control? Hong Lin, Ph.D. P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)45 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Understanding basics of unit operations and processes (UOP) are fundamental for design, analysis and monitoring of Best Management Practices (BMP) for urban runoff pollution control. In physical separation processes such as hydrodynamic separation and filtration, particulate size plays an important role. Performance of these systems typically is evaluated by removing the mass of the particulate pollutants. In order to select the appropriate technology and design unit adequately to meet the desired performance, particle size distribution for the pollutants is one of the most critical physical characteristics to investigate and to be understood.

Select this Article		Particulate Matter Particle Size Distributions Transported in Urban Runoff J.‐Y. Kim, Ph.D., M. ASCE and J. Sansalone, Ph.D., P.E., M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)46 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A very wide size range of particulate matter (PM) transported in urban stormwater poses significant challenges to sampling, analysis and control. In addition, mis‐application of particle analysis often have the potential to cause misrepresentation of hetero‐disperse PSD in urban stormwater by failing to characterize the entire gradation; or are carried out after sample holding time (< 12 hours) has resulted in natural coagulation and flocculation to occur. A methodology is developed which parallels particle size analysis from geotechnical engineering to characterize event‐based size distribution of PM transported in urban stormwater by sampling and also analysis of the entire PM size range transported in runoff. This paper presents the non‐colloidal PSDs for event‐based size distribution of PM ranging in size from 1 μm to larger than 24,500 μm transported during urban runoff events. Through a literature review, the PSD results in this study were compared to those PSDs in urban runoff previously published in the literature with details of sampling and analytical methods employed. In order to demonstrate the validity of stormwater PSD results, mass balance error analysis, requiring a 90% mass recovery, was carried out for each monitored event. While the non‐colloidal PSD results in this study demonstrate that urban stormwater transports PM in size ranging from 1 μm to larger than 24,500 μm, PSDs from the literature focus on more limited size ranges. With the common stormwater application of automatic samplers appropriately developed for less dense suspended floes from steady wastewater flows, the coarser fraction of the gradation is truncated by such sampling, in particular for source area runoff. Additionally, sample holding times that allow coagulation and flocculation truncate the suspended fraction of the gradation. Ultimately, urban environs and receiving water are impacted by the entire PM gradation, but through differing mechanisms and time scales; resulting in the need to characterize and control the entire gradation. Because of the hetero‐disperse nature of runoff PM, the suspended fine fraction is appropriately characterized and controlled based on particle volume/number and in contrast, on a gravimetric basis for the coarse fraction larger than 75 μm.

Select this Article		Total Suspended Solids: Is It for Real? James J. Houle, Pedro Avellaneda, Robert M. Roseen, M. ASCE, P.E., Ph.D., and Thomas P. Ballestero, M. ASCE, P.E., Ph.D. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)47 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Stormwater treatment device selection is largely governed by regulatory compliance. Often stormwater management strategies are selected to comply with a regulatory performance requirement rather than being designed based upon actual performance characteristics of the systems. While technical performance evaluation of stormwater treatment devices is an evolving science, regulatory guidelines struggle to keep in step with regional demands for information. A discussion of the origin of a TSS performance standard and its potential limitations is presented against a comprehensive statistical analysis of pollutant relationship patterns of influent and effluent water quality across a range of stormwater management practices. Complex pollutant relationships, or lack‐there‐of, suggest that In the future we will need to integrate our stormwater designs into the building blocks of regional watershed improvement strategies with careful attention to altered hydrology. One effective means for addressing this is by implementing innovative BMPs employing some form of filtration or infiltration mechanisms. Selection criteria that possess a foundation in regional watershed protection objectives need to be advanced using standards of performance that examine the fundamental causes of watershed impairment, namely altered hydrology.

back to top

TOTAL WATER MANAGEMENT

Select this Article		How to Export Water and Grow Supplies in Your Own Basin: Balancing Agricultural, Urban, and Environmental Water Needs in the Lower Colorado River Leah Manning, P.E., Gary Guy, P.E., and Susan Butler ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)48 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The Lower Colorado River Authority‐San Antonio Water System Water Project (LSWP) is a cooperative effort between two regions in central Texas. The general project area in south central Texas is shown in Figure 1. The LSWP would conserve and develop water in the Lower Colorado River (Texas) basin in three ways: 1) Reduce agricultural irrigation water demand through conservation practices, efficiencies and measures. 2) Capture and store excess and unused river flows. 3) Use limited amounts of groundwater for agriculture in the Lower Colorado Fiver Basin when surface water is not available.

Select this Article		Problems and Challenges in Water Resources Management — A Municipal Water Manager's Perspective Peter D. Binney, P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)49 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Access to an assured supply of fresh water is critical to sustain ourselves, our communities, the economies in urban and rural areas that have grown as a result of our development of the West and for the environment that we live in. We have developed some of the largest economies and population centers in the world in this semi‐arid climate subject to climate variation, aridity and drought. Forecasts are for substantial population growth, sustainability and expansion of those economies and expectations of a vital ecosystem will place even greater demands on our natural resources across the West. At this time, we are over‐subscribing the capacity of these natural water systems and shortages are being experienced. The water manager must consider a range of adaptive strategies to create an acceptable balance of solutions to meet those multiple needs in this highly political and contentious setting.

Select this Article		Total Water Management Tools and Process to Address Water Resources Management Challenges: Botany Case Study in Sydney, Australia Jacqueline Kepke, P.E., Ken Wright, and Sally Williamson ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)50 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The Sydney Metropolitan area is currently undergoing significant expansion. At the same time, the effects of climate change are already being felt in Australia, with a severe drought driving the need to provide water, wastewater, and stormwater service that new development using an integrated and sustainable water resource approach. The type of development that presents the greatest challenges as well as opportunities from a water service standpoint is infill growth. In the Botany Infill Growth Area in Sydney, which incorporates the Wolli Creek, Green Square, and Sydney Airport areas, rapid commercial and residential development is occurring, including many high rise apartment buildings. As developers move forward with their plans, Sydney Water Corporation is developing an integrated strategy for providing water, sewer, and stormwater services to the area. This strategy will support decisions on development approvals, as well as providing SWC with strategic direction to move forward with sustainable integrated water cycle management.

back to top

URBAN WATERSHED MANAGEMENT: A WATERSHED APPROACH

Select this Article		Looking All Over for Urban Storm Water BMP Opportunities — An Island‐Wide Storm Water Retrofit, Oahu, Hawaii Chin Y. Lien, P.E., Richard C. V. Dahilig, P.E., Curtis K. Matsuda, P.E., and Todd Nishioka ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)51 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract As a proactive effort and as part of its NPDES MS4 program, Hawaii Department of Transportation, Highways Division (HDOT‐HWYS) is conducting an Island‐wide feasibility study for retrofitting its existing MS4 system on the Island of Oahu that discharges to the receiving waters listed on the Section 303(d) of the Clean Water Act. The targeted pollutants include sediment, siltation, turbidity, and/or trash. The retrofits are to include both source‐control and stream‐based control as well as maintenance related best management practices (BMPs) designed to improve water quality of the receiving streams, bays and ocean. Major objectives of the study include: 1 Identify and evaluate potential pollutant sources from HDOT MS4 that may cause storm water pollution and stream degradation; 2 Identify management measures related to HDOT Highways activities for the pollutant reduction and reestablishment of stream stability; 3 Identify potential opportunities for installing permanent BMPs controls within HDOT right‐of‐way; 4 Rank and prioritize management and control BMPs identified in the study.

back to top

URBAN WATERSHED MODELING (I)

Select this Article		An Innovative Stormwater Best Management Practice Decision Support System for Quantifying and Optimizing Load Reductions and Costs in Los Angeles Stephen Carter, P.E., Jenny Zhen, Ph.D., Andrew Parker, and Bowman Cutter, Ph.D. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)52 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Protecting environmental quality requires a comprehensive approach that heavily relies on our ability to confidently predict or forecast impacts, evaluate the ability of natural systems to absorb impacts, and determine the combination of options that will provide an acceptable level of protection and/or restoration. These forecasts, when accepted, can help stakeholders to understand the potential cost or implications of restoration options and guide the development of effective protection strategies that can mitigate and prevent adverse impacts. Forecasts, which are typically based on combinations of modeling and analysis, must be designed to be sensitive to changes in the watershed and to in‐stream responses. The difficulty with forecasts is that they are just predictions based on what we know now and what we believe might happen in the future. That is why environmental protection studies emphasize rigorous science‐based approaches that can build confidence in forecasts. Building on an extensive body of relevant studies in the Los Angeles region, including monitoring, model development, and regional model parameterization efforts, this study is designed to develop and apply a Best Management Practice Decision Support System (BMPDSS) for the evaluation of alternative storm water best management practices (BMPs) and Low Impact Development (LID) methods. The system allows managers to evaluate the ability of various BMP scenarios to provide necessary flow volume and pollutant load reductions for Total Maximum Daily Load (TMDL) implementation and optimizes the scenarios based on benefits and costs. The approach is designed to provide guidance for a public incentive plan for implementing onsite BMP/LID techniques. The framework developed in this study provides a technically defensible and repeatable basis for evaluating quantitative measures associated with alternative BMP implementation plans. The BMPDSS represents an advanced method for simulating BMP processes and analyzing benefits (e.g., load reductions). Results of this study provide an interesting glimpse into the most relevant and economical BMPs for typical land uses in the Los Angeles watershed.

Select this Article		Collection System Model Development Using Raster Imperviousness Data Mitchell C. Heineman, P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)53 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Imperviousness has traditionally been a principal calibration parameter for collection system models. The 2007 publication of the National Land Cover Database impervious surface raster dataset, and in Massachusetts, a 1‐m statewide impervious surface raster dataset, mean that imperviousness for United States urban collection systems is now readily computed. Calibration can instead focus on determining the transfer fraction from impervious to pervious surfaces. For citywide sewer and drain system models in the city of Boston, average measured imperviousness for storm drainage was 50 percent in neighborhoods with separated sewers. Model calibration yielded an average transfer fraction of 67 percent, resulting in an effective imperviousness of 17 percent. In portions of the city with combined or partially separated sewers, measured imperviousness was 72 percent. The calibrated average routing fraction was 66 percent, yielding an effective imperviousness of 25 percent. These results demonstrate that calibration to measured runoff remains critical to model development, as a high fraction of flow is routed from impervious to pervious surfaces. Methods for estimating transfer fractions exist, but further study should evaluate patterns and differences among urban areas.

Select this Article		Evaluation of Low Impact Development models for Storm Water Flow Reduction and Demand Management in Downtown Seattle Nian She, Alicia Chase, and Joseph Pang ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)54 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The combined sewer overflow to Downtown Seattle's water front has been a problems for many years. The City has been evaluating different strategies to reduce the stormwater flows into City's infrastructure. One of the strategies is to evaluate low impact development (LID) alternative such as green roof retrofit, bioretention and porous pavement or the combination of any of them. This paper compares various LID models used to perform stormwater evaluations for Seattle's downtown basin. All models are running for continuous simulations for 29 year — 5 minutes rainfall data. Uncertainties associated with each model run are setup to assess the reliable reduction of stormwater flows.

Select this Article		Simple Rainfall Loss Models for Rainfall‐Runoff Modeling Theodore G. Cleveland, Xin He, and David B. Thompson ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)55 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Unit hydrographs are developed for a specific watershed using two basic approaches. If unit rainfall‐runoff data are available, then numerous techniques can be applied to estimate a unit hydrograph from the data. If no data are available, then methods of synthetic hydrology must be applied. Current practice is regionalization of measured behavior used to transfer known hydrographs (or other hydrologic entities) from a location where measurements are available to unmonitored watersheds. The regionalization involves determining time parameters for the unit hydrograph procedure, which may include time to peak, time base, or time of concentration. Regionalization also involves development of regional regression equations for time parameters, watershed and/or rainfall characteristics. The principal elements required for the synthetic approach are the determination of characteristic loss features (loss model) and characteristic response time (unit hydrograph model). The authors observe that even if the temporal redistribution of excess rainfall is performed using hydraulic models, which is certainly feasible and often the most appropriate approach, then there is still need to understand how to convert the rainfall signal into an excess rainfall signal, and this will be accomplished with some kind of loss model. In the collective literature losses are correlated with watershed soil properties, while the characteristic response time is associated with physical characteristics such as watershed drainage areas, main channel and overland flow slopes, characteristic lengths, and characteristic velocities. Unit hydrograph parameterization was examined based on topographic information and simple loss models to predict the runoff volume, rate and timing with minimal watershed characterization, using data readily available to drainage engineers. Results from the approach were compared with observed rainfall‐runoff responses and are reported herein.

Select this Article		Urban Stormwater Modeling: Status in 2008 Wayne C. Huber and Eric W. Strecker ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)56 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Stormwater modeling in urban areas has risen to a high level of accomplishment, yet many improvements and research needs remain. This paper summarizes a foundation‐type conference on the state‐of‐the‐art of urban stormwater modeling, held in July 2007. Conference highlights and research needs are provided.

back to top

URBAN WATERSHED MODELING (II)

Select this Article		Continuous Hydrologic Modeling Improved by Intensive Event Data Xuefeng Chu, A. M. ASCE and Alan D. Steinman ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)57 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Continuous hydrologic modeling for a watershed involves characterization of a series of hydrologic processes affected by numerous factors over a long time period, which consists of both wet and dry conditions with/without rainfall. The complexity of those processes and their cumulative effects, and the lack of intensive long‐term monitoring data, often prevent a modeler from effectively identifying the underlying processes and mechanisms, as well as accurately estimating the relevant hydrologic parameters. To circumvent this difficulty, a modeling strategy that combined event and continuous hydrologic modeling was implemented in this study. The fine‐scale event hydrologic modeling, supported by intensive storm data, was used to improve the coarse‐scale continuous modeling by providing more accurate and well‐calibrated parameters. Two different rainfall‐runoff models: the soil moisture accounting (SMA) and the SCS curve number (SCS‐CN) models in HEC‐HMS were utilized and discussed. In an application to the Mona Lake watershed in west Michigan, the Watershed Modeling System (WMS) and HEC‐HMS were coupled for processing spatially‐distributed GIS data, delineating the watershed, computing geometric and hydrologic parameters, and implementing hydrologic modeling. Several rainfall events were selected for calibrating/verifying the event model and identifying the related parameters, which were further used in the continuous hydrologic model. Two methods: normalized objective function (NOF) and modeling efficiency (EF) were utilized to quantify the goodness‐of‐fit between simulated and observed hydrographs and evaluate the model performance. Results from this study reveal that the joint event and continuous hydrologic modeling can be effective, as it takes full advantage of different hydrologic approaches and available data, and improves the overall quality of watershed hydrologic modeling.

Select this Article		Development and Application of a Water Quality Management Model of Eutrophic Onondaga Lake, NY Pradeep Mugunthan, James R. Rhea, David Glaser, Kevin Russell, Li Zheng, and Joseph J. Mastriano ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)58 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The water quality of Onondaga Lake, NY has been compromised by a 100‐year history of municipal and industrial pollution. A state‐of‐the‐science water quality model was developed for the system to facilitate contemporary water quality management which includes: 1) development of total phosphorus and ammonia TMDLs and 2) assessing the feasibility of diverting a large point source discharge out of the Lake and into an adjacent river system. The OLWQM consists of a number of submodels representing the major hydrodynamic, water column nutrient cycling, and sediment processes controlling water quality in the lake. The water column submodel describes nitrification, organic matter decomposition, algal photosynthesis, respiration, and nutrient uptake, and zooplankton and zebra mussel grazing and respiration. The sediment flux submodel simulates the conversion of particulate organic material settling from the water column to dissolved nutrients and the concurrent consumption of oxidized compounds from the overlying water column. The model was calibrated over the period from 1994 to 2003 and successfully simulated the major water quality dynamics observed within the system. Additionally, the model simulated the gross patterns in chlorophyll‐a in the epilimnion as well as phosphorus retention within the lake sediments. Finally, the model was able to simulate compliance‐based measures of important water quality standards and guidance values developed for the lake. The next step of model development includes linkage of the Lake model with a model of the adjacent river system and validation of the linked models.

Select this Article		Small Watershed Response Models: Hydrologic or Hydraulic? Theodore G. Cleveland, William Botkins, and David B. Thompson ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)59 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The response of a small, 32.3 hectare (80 acre), watershed in Harris County to rainfall is simulated entirely hydrologically using the geomorphic instantaneous unit hydrograph (GIUH) methods of Cleveland and others. The simulation is repeated using SWMM 5.0 and only hydraulic elements (entirely hydraulic simulation) for the same watershed, and the same rainfall input. The results are compared to observed rainfall and runoff for the watershed, and produce similar performance. The two simulation approaches are comparable to each other suggesting, among other things, that: 1 A hydrologic model, adequately parameterized captures more than enough hydraulic behavior to estimate watershed response. 2 A hydraulic model for a small watershed is a feasible tool to parameterize a hydrologic model. Such an exercise would be of value when constructing complex integrated hydrologic models, and when incorporating physical changes on the watershed from development, drainage improvements, etc. 3 The GIUH results in this study for this fully developed watershed indicates that the topographic relief and a characteristic velocity reflective of full development captures the essential behavior of the watershed. These findings indicate that hydraulic models can be used to develop a hydrologic responses that are fully traceable in terms of physical characteristics on the watershed, and that the decision to use a hydraulic model or hydrologic model for small watersheds is one of analyst choice, data availability, and project need.

back to top

COUPLING PHYSICAL, CHEMICAL, OR BIOLOGICAL METHODS FOR INNOVATIVE GROUNDWATER REMEDIATION

Select this Article		The Effect of Oxygen Transport on Biotransformation of Trichloroethylene in the Subsurface Wonyong Jang and Mustafa M. Aral ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)60 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Trichloroethylene (TCE) is one of the most‐frequently‐detected chemicals in the contaminated groundwater. In the subsurface, TCE can be biodegraded by indigenous microorganisms through coexisting aerobic and anaerobic bioprocesses, which are determined mostly by oxygen, energy sources, and electron acceptors. The bio‐processes generate different benign or toxic byproducts. We investigate oxygen transport, induced by the density‐driven gas flow and groundwater flow, and the effect of oxygen presence on the fate of TCE and its associated byproducts via the variation of aerobic and anaerobic bioprocesses in the unsaturated and saturated zones. In this study, the types and rates of the bioprocesses depend only on the oxygen‐concentration level. Fully coupled nonlinear multiphase flow and multi‐species transport equations are formulated and solved using the Galerkin finite element technique. Both sequential dehalogenation and aerobic cometabolic biodegradation of the contaminants are considered. The aerobic bioreaction under oxic conditions had significant impacts on the fate of TCE's byproducts in the subsurface.

Select this Article		Using Solute Age Distribution to Assess the Potential for Future Degradation of Groundwater Quality and to Prioritize Remediation Activities Heather O'Shea and Roseanna M. Neupauer ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)61 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A groundwater sample contains a collection of water and solute molecules that entered the aquifer at different times. The distribution of times that the solute molecules entered the aquifer is called a solute age distribution. Assuming ergodicity, a solute age distribution is equivalent to the backward travel time probability density functions (PDF) between the sample location and the land surface. A backward travel time PDF represents the random travel time from an upgradient point of interest (e.g., the land surface) to the sample location, and can be calculated efficiently by solving the adjoint of a forward transport equation. The solute age distribution can be used to assess the potential for future degradation of groundwater quality, and to prioritize remediation activities. We calculate solute age distributions for a stream in Colorado that has been contaminated due to mining activity. We use the solute age distribution to prioritize mine sites for remediation. The highest priority is given to the site whose remediation would lead to the most substantial improvement in the water quality of the stream.

back to top

GROUNDWATER HYDROLOGY AND QUALITY MODELING

Select this Article		A Mixed Lagrangian‐Eulerian and Finite Element Approach to Modeling Variably Saturated Flows in Three Dimensions Gour‐Tsyh Yeh and Hua Shan ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)62 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A robust, efficient numerical solution of variably saturated flows in three dimensions will be presented. The solution algorithm was developed by applying the mixed Lagrangian‐Eulerian (LE) and Finite Element (FE) approach to Richard's equation. The Lagrangian‐Eulerian approach with accurate and robust particle tracking algorithms has been considered a better resolution for sharp front problems. However, the implementation of the algorithm to the advective form of the Richards equation has encountered difficulties resulting from the flux boundary conditions. Therefore, it was decided to develop a mixed LE and FE approach to circumvent the problem. In this approach, LE method was applied to interior nodes and the FE method to incoming‐flux‐boundary nodes. The goal was to develop numerical tools that can efficiently analyze the flow behaviors in saturated/unsaturated porous media. Application of the hybrid approach to a test problem shows that it is more robust and efficient over the conventional finite element methods.

Select this Article		Use of WHPA Model on GIS Platform for Aquifer Vulnerability Assessment A. K. Tyagi, F. ASCE and V. Balasubramanian ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)63 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract This paper uses a module of the wellhead protection area model to delineate the zone of capture for five well fields for the city of Enid located in Oklahoma. There are about twenty‐five wells in each of the well fields. This model developed by the Environmental Protection Agency is now connected to the Geographical Information System in this research, indicating the zone of capture for the five fields.

back to top

GROUNDWATER INVERSE MODELING

Select this Article		Identification of Contaminant Sources in Aquifers under Uncertainty Jiabao Guan and Mustafa M. Aral ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)64 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The identification of contaminant sources in aquifers is an important issue for the protection of groundwater resources. Recently, various models, including analytical and numerical solutions, have been proposed to solve this problem. In most of these applications the contaminant source identification problem was analyzed using deterministic models. For example, in these applications it was assumed that the aquifer is homogeneous and it has a well‐defined hydraulic conductivity distribution. In this study, the parameters such as the hydraulic conductivity and dispersion coefficients are considered to be uncertain parameters. In this study we represent this uncertainty using fuzzy sets. The fuzzy membership functions used in this representation may be based on field data or expert knowledge. Using this approach, the contaminant source identification problem is formulated as an optimization model with fuzzy parameters. The solution is obtained by coupling the genetic algorithm (GA) and vertex method as it is applied to the solution of the optimization model. A hypothetical aquifer is used to demonstrate the effectiveness of the model and the algorithm. The results show that the proposed model can reliably identify the locations of contaminant sources and their release histories for uncertain parameters and the proposed algorithm is shown to be efficient.

back to top

GROUNDWATER MANAGEMENT

Select this Article		Conjunctive Use and Other Adaptation Strategies to the Impacts of Climate Change in California Water Resources S. Vicuna, J. A. Dracup, and Larry Dale ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)65 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract There is a growing evidence of that climate change could potentially affect California hydrology and water resource systems. Projections of these climate change conditions imply with high certainty increases in temperature and the associated earlier timing of snowmelt runoff, however projections of changes in precipitation and the associated water available are less certain, some studies showing higher levels of precipitation while others show drier conditions. Is it possible with this knowledge to design adaptation strategies that could be used to mitigate the impacts associated with climate change? And when should these strategies be implemented? Those are some of the questions we answer in a case study of Merced River Basin operations. We approached this problem using an optimization technique known as Sampling Stochastic Dynamic Programming which allows the derivation of reservoir and aquifer operating rules for the considering non‐stationary hydrologic conditions such as those associated with climate change. The alternatives we explore follow into three categories: operational changes (changing flood control rules to accommodate earlier timing of inflows); infrastructure changes (increasing storage capacity to accommodate increasingly varying reservoir inflows) and; institutional changes (conjunctive use institutional framework which increases the potential for artificial recharge and a better handling of changing in timing of hydrologic conditions).

Select this Article		Design and Installation Challenges of Large and Deep Production Wells in South Florida Girma Mergia, P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)66 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A new power plant in south Florida required more than 10,000 gallons per minute (gpm) of reliable groundwater supply for operation. Existing data collected during the design stage indicated poor water quality, especially in the deeper zone of the aquifer. Three production wells were designed, installed and tested on a tight schedule to facilitate plant startup. Each well can yield a minimum of 4,500 gpm. The wells are approximately 1,300 feet in depth and have 24 inch diameter fiberglass reinforced plastic (FRP) inner casings extending from the ground to approximately 1,000 feet below the ground surface. Each well produces groundwater from 23‐inch diameter, 300‐foot long open holes in the Upper Floridan Aquifer (UFA). Critical design considerations for the wells included adequate groundwater yield, water quality, cost and schedule. The complexity of the well design required onsite supervision by a qualified local hydrogeologist during critical phases and continuous Black & Veatch (B&V) oversight of all activities. A number of unexpected circumstances were encountered during the installation of the wells. This paper discusses the site hydrogeologic, water quality and aquifer yield conditions considered during the well design. The paper also highlights installation difficulties, as well as steps taken to overcome them.

Select this Article		Using Density‐Dependent Numerical Models to Evaluate Regional Groundwater Flow Patterns in South Florida Laura D. Bittner, Emily Richardson, Christian D. Langevin, Stephen M. England, and Glendon T. Stevens ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)67 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A variable‐density groundwater model was developed for the southern half of Florida as part of a regional study to predict the effects of planned aquifer storage and recovery operations. A persistent problem with the model development was that simulated heads in the southern part of the Florida peninsula were consistently less than observed values. Six tests were performed with the numerical model to try and identify the most likely causes of the discrepancy. The tests included explicit representation of (1) permeable fracture zones, (2) regional horizontal anisotropy, (3) low permeability deposits on the ocean floor, (4) disequilibrium from past sea‐level stands, (5) increased hydraulic connection through confining units, and (6) the effects of pressure and temperature on fluid density and viscosity. Test results suggest that combining (2) and (6) provides the best match with the observed heads. Future efforts will focus on improving models of the regional flow system.

back to top

GROUNDWATER QUALITY AND HUMAN HEALTH

Select this Article		Risk Assessment Embedded with Prospect Theory for Groundwater Protection from Terror Threats Anna M. Doro-on and C. S. Rocky Shih ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)68 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Protection of drinking water reserves has been the primary concern for governing agencies, environmental stakeholders, and the general populous worldwide. The capability of engineers and planners to incorporate risk assessment in policy-making, offers a valuable tool for implementation of sound policy regarding groundwater protection, while providing an open forum type vehicle to incorporate public inputs in priority setting for protection decisions. This paper illustrates a risk assessment methodology based on prospect theory based on prospect theory systematically analyze alternative recharge zone protection approaches and respective probabilistic impact on groundwater resources, as motivated by recent development over the recharge zone of a sole source aquifer for one of the largest metropolitan areas in the United States. Logical relationships, characterized using fault tree analysis, accurately describe pathways leading from the initial policy decision to final consequences. Comparison of these risk probabilities with limits based on revealed preference concept and prospect theory, affords decision-makers the ability to screen alternatives for acceptability.

back to top

IMPACTS OF URBANIZATION ON GROUNDWATER QUALITY

Select this Article		Material Characterization and Reaction Kinetics of Green Sorption Media for Nutrients Removal Ni‐Bin Chang, Marty Wanielista, Fahim Hossain, and Lisa Naujock ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)69 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract In water scarce areas throughout the world, stormwater and wastewater used as an alternative water supply have been put into practice to promote the sustainability of our water infrastructure. Also, in water rich areas, stormwater management and on‐site wastewater treatment systems are highly susceptible to extremes in precipitation causing wide spread pollution problems. High nitrogen and phosphorus content in stormwater and wastewater effluents has impeded reuse potential and impacted ecosystem integrity and human health. Nitrate may be toxic and can cause human health problem such as methemoglobinemia, liver damage and even cancers. Phosphorus may trigger the eutrophication issues in fresh water bodies, which could result in toxic algae and endanger the source of drinking waters eventually. It aims to conduct the material characterization and examine the reaction kinetics of a selected recipe of green sorption media recycled from waste streams, such as sawdust and tire crumb, combined with sand/silt and limestone, for nutrient removal using packed bed column tests as a means. Pollutants of concern include ammonia, nitrate and ortho‐ phosphate. Application potential in stormwater management and wastewater treatment facilities was discussed in the context of sustainable systems engineering.

back to top

INTEGRATED STREAM AND GROUNDWATER MANAGEMENT

Select this Article		The Conjunctive Use of Reservoirs and Aquifers: Tradeoffs in Electricity Generation and Water Supply Larry L. Dale, S. Vicuna, and J. A. Dracup ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)70 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Although the literature on conjunctive use of surface and groundwater is extensive few papers have analyzed the benefits of coordinating reservoir and aquifer operations. In this work we evaluate reservoir and aquifer operations under three different management schemes. We constructed a monthly non‐linear programming model embedded into an annual stochastic dynamic programming model (SDP/NLP model). This model was applied to a case study of the operations of the Merced River Basin, located in the eastern San Joaquin Valley. In a first phase of this application we calibrate the model parameters to match historic operations and the historic level of reservoir‐aquifer coordination. We then use the model to estimate the benefits of managing water storage under different institutional and economic scenarios. The scenarios include an electric power scenario (where the reservoir is operated to maximize hydropower benefits), a conjunctive use scenario (where reservoir and aquifer releases are jointed managed to maximize hydropower and agricultural benefits), and a non conjunctive use scenario (where the reservoir is operated independently of groundwater controls).

Select this Article		Developing a Conflict Resolution Model for Groundwater Quantity and Quality Management: A Case Study M. R. Bazargan‐Lari and R. Kerachian ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)71 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract In this paper, a conflict resolution methodology for conjunctive use of surface and groundwater resources is developed using Nondominated Sorting Genetic Algorithm II (NSGA‐II) and the Young conflict resolution theory. The proposed model is applied to the Tehran Aquifer. Annual domestic water consumption in the Tehran metropolitan area is close to one billion cubic meters. The sewer system in this region consists of the traditional absorption wells and domestic waste water pollutes groundwater resources. Some part of the domestic wastewater is drained into local rivers and partially contaminates the surface water resources. This polluted surface water is used in conjunction with groundwater for irrigation purposes in the southern part of the Tehran. Decision makers and stakeholders in the study area have some conflicting interests such as water supply with acceptable quality, reducing the pumping costs, improving the groundwater quality, reducing the construction costs of the Tehran waste water collection system and controlling the groundwater table fluctuations. In the proposed methodology, the MODFLOW and MT3D groundwater quantity and quality simulation models are linked with the NSGA‐II optimization model to develop a Pareto front among the objectives. The best point on the Pareto front is then calculated using the Young conflict resolution theory. The results of the proposed model show the significance of applying an integrated approach to surface and groundwater resources in the study area.

Select this Article		Integrated Hydrologic Study of the Inarajan and Tinaga River Basins Inarajan, Guam Jack C. Robinson, Kate E. Richards, Anthony Daus, and Amelia Tallman ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)72 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Geomatrix has conducted a hydrogeologic assessment of the Inarajan and Tinaga River basins in southern Guam to develop an integrated conceptual hydrologic model of groundwater and surface water interactions in support of potential landfill design and construction. Currently, few hydrologic studies have focused on southern Guam. The model indicates that surface water and groundwater levels are very dynamic in the study area. During below average precipitation years, surface water flow is maintained primarily by groundwater in the dry season and a more balanced contribution of groundwater and precipitation runoff in the rainy season. During above average precipitation years, summer storms interrupt the dry season, resulting in greater surface water flows during the summer months, creating less defined wet and dry seasons. Topography and, to a lesser extent soil type, exhibit the greatest influence on the interactions between surface water and groundwater in the study area. With the onset of the rainy season, headwaters areas for local rivers, exhibiting flatter topography, wetland vegetation, and laterite soils exhibit more rapid rises in groundwater levels than upland areas with more irregular and steeper topography and saprolite soils.

back to top

POSTER SESSION II: GROUNDWATER SYMPOSIUM

Select this Article		A Comparison between BIOCHLOR and the Analytical Contaminant Transport Analysis System (Acts) for a Case Study in Coastal Georgia R. J. Suárez‐Soto, B. A. Anderson, M. L. Maslia, and M. M. Aral ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)73 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Recent literature articles have highlighted approximation errors inherent in the Domenico analytical solution for describing contaminant fate and transport in groundwater. The Domenico solution is included in two widely‐used analytical contaminant fate and transport models—BIOCHLOR and BIOSCREEN. These screening‐level models are often used to determine the feasibility of contaminant remediation by monitored natural attenuation. In this paper, the authors compare results obtained from the Domenico solution (BIOCHLOR) to results obtained from another public domain analytical modeling software platform, the analytical contaminant transport analysis system (ACTS). ACTS incorporates an exact analytical solution given by Wexler to quantify contaminant fate and transport in a two‐dimensional, infinite aquifer model. The two models are applied in a probabilistic approach for a case study at Oatland Island, Georgia, USA. Because the Wexler approach provides an exact analytical solution, the authors suggest that ACTS provides a more accurate screening analysis tool.

Select this Article		A Mass Balance‐Based 1D Mass Transport Model Andrew Curtis Elmore, Ph.D., P.E., M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)74 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Groundwater remedial design typically requires the development of a reliable mass transport model to evaluate clean up alternatives. A major challenge in the development of a mass transport model is the identification of source release terms such as location and time of release. Although the source location may be characterized during site investigations, the time terms are unknown or poorly known at many sites. This study uses a mass balance‐based approach to explicitly account for uncertainty in rectangular pulse release time variables instead of using inverse techniques to rigorously define the release history. The mass balance approach relies on the collection of groundwater concentration data and the standard assumptions used to develop one‐dimensional solutions to the advection dispersion equation. A spreadsheet model has been developed to accommodate Monte Carlo simulations, and a concentration dataset from a Nebraska Superfund site was used to evaluate the model. Reasonable results were achieved when the source time parameters were assumed to be random, and the results improved when the mass of contaminant in the aquifer was also assumed to be random.

Select this Article		A Preliminary Analysis of Field‐Scale Infiltration into Layered Soils R. Morbidelli, R. S. Govindaraju, C. Corradini, C. Saltalippi, and A. Flammini ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)75 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A preliminary analysis directed towards developing a model for the expected areal‐average infiltration into a layered soil profile is presented to represent the random spatial variability of the saturated hydraulic conductivity. The basic framework investigated for the model is the one proposed earlier for vertically homogeneous soils, that should be combined with the model for local infiltration into a two layered soil profile. In this context the possibility of reducing the complexity of a local modelling, which relies on the numerical solution of a system of two ordinary differential equations, is analysed by developing parameterized relations for the time to ponding at the surface and the suction head at the bottom of the upper layer.

Select this Article		Proper Soil Textural Sequence for Septic Tank Systems Richard D'Amato, Ph.D., A. M. ASCE and Michael Meadows, Ph.D. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)76 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract During the mid 1990's, the South Carolina Department of Health and Environmental Control (SCDHEC) and the University of South Carolina (USC) entered a joint project to address concerns about groundwater contamination from domestic septic tank systems along the South Carolina coast. Evidence of system failures through the years had been documented in these areas of typically shallow mean groundwater levels. The project employed monitoring wells located along the South Carolina coast and also undertook an extensive modeling effort. The modeling revealed a perceived weakness in the traditional listing order of soils used by many environmental departments in classifying soils for septic tank and absorption field systems (STSAS). This paper will present the case for reordering these soils to better match their failure potential as indicated by the models.

Select this Article		Reasons Behind Failure of Qanats in the 20th Century Kaveh Madani ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)77 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Qanats are renewable water supply systems that have sustained human settlement in arid areas such as Iran. By their very nature, Qanats have encouraged sustainable water use for millennia. However, the socio‐economic changes in the 20^th century introduced other water harvesting methods such as deep wells whose immediate advantages caused Qanats to be laid aside even though the application of these new methods alone could not contribute to achieving sustainable water resources. By developing the Causal Loop Diagrams of the problem, this study focuses on the interaction dynamics of Qanats and deep wells to explore the physical and socio‐economical reasons of Qanats failure in the 20^th century.

Select this Article		Source, Distribution and Release Mechanisms of Arsenic in the Groundwater of Assam Floodplains of Northeast India Chandan Mahanta, Nayanjyoti Pathak, Prosun Bhattacharya, Gustav Enmark, and Daniel Nordborg ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)78 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract This study conducted in Bongaigaon and Darrang districts of Assam, India is based upon water chemistry and sediment characteristics investigation in an reportedly arsenic infested belt. Of total 50 sampled wells, 15 had arsenic concentration above national drinking water standard of 50 μg/l, and 33 had As concentrations above the WHO guideline of 10 μg/l. However no distinct zones or depths with specific sedimentological features could be identified. Sediments with colour on green‐olive scale are probably more likely to bear As contaminated water than white sediments. Sand filters used to reduce high iron content seem to reduce As content of water effectively. Arsenic rich water is also partly avoided since drillers seek water low in iron, which is often also low in arsenic content. Reductive dissolution of Ferric hydroxides is believed to be the release mechanism controlling the mobility of arsenic, rather than oxidation of arsenopyrite or pH induced desorption.

back to top

PROBABILISTIC METHODS FOR GROUNDWATER MODELING

Select this Article		Historical Reconstruction of PCE‐Contaminated Drinking Water Using Probabilistic Analysis at U.S. Marine Corps Base Camp Lejeune, North Carolina R. J. Suárez‐Soto, J. Wang, R. E. Faye, M. L. Maslia, M. M. Aral, and F. J. Bove ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)79 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The historical reconstruction process is used to derive contaminant concentrations and exposure levels needed as input by health scientists conducting retrospective epidemiological studies—models are an integral part of this process. However, the models and associated calibrated parameters are inherently uncertain because they are based on limited historical data and information. This gives rise to the question, what is the reliability of the historically reconstructed estimates of contaminant concentrations determined using calibrated models? To answer this question and address the overarching issues of model and parameter variability and uncertainty, a probabilistic analysis is used to generate uncertainties of model inputs (e.g., hydraulic conductivity or contaminant source mass loading rate) so that estimates of uncertainties in model outputs (e.g., water level or contaminant concentrations in groundwater) can be made. In this paper, the authors describe the application of a probabilistic analysis using Monte Carlo simulations to assess model uncertainty and parameter variability. The probabilistic analysis is applied to groundwater‐flow and contaminant fate and transport models (MODLFOW and MT3DMS, respectively) as part of an ongoing health study—exposure to volatile organic compounds in drinking water and specific birth defects and childhood cancers—being conducted by the Agency for Toxic Substances and Disease Registry at U.S. Marine Corps Base Camp Lejeune, North Carolina (Figure 1). Results of probabilistic analysis are presented in terms of the probability of occurrence tetrachloroethylene (PCE) contamination in groundwater, the probability of exceeding the current maximum contaminant level for PCE in finished drinking water (5 micrograms per liter), and the range of expected PCE concentrations in finished drinking water during the historical period of interest (1968–1985) for the health study.

Select this Article		The Importance of Using Probabilistic Effective Hydraulic Conductivity in Dairy's Law and Groundwater Flow Calculations Hugo A. Loáiciga ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)80 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The effective saturated hydraulic conductivity is a parameter that relates the average groundwater specific discharge to the average hydraulic gradient. This paper outlines a procedure to calculate the effective saturated hydraulic conductivity in local‐scale groundwater flow. Examples are presented in this work.

back to top

SALTWATER INTRUSION MODELING/MANAGEMENT

Select this Article		Effect of Beach Permeability and Freshwater Recharge on Beach Hydraulics Hailong Li, Michel C. Boufadel, and Albert D. Venosa ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)81 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Measurements of water level, salinity, temperature, and a conservative tracer (Lithium) were obtained from a beach in Prince William Sound (PWS), Alaska. The ultimate goal of the measurements was to evaluate the factors affecting the lingering of oil in the beaches, 17 years after the spill of the Exxon Valdez. The tidal range at the beach was ∼4.8 meters, a large value that minimized the effects of salt density gradients. The results were simulated using the code MARUN, a finite element code for density‐dependent flow in two‐dimensional variably‐saturated media. Preliminary calibration of the model revealed that the water level within the beach was greatly dependent on permeability and the freshwater recharge.

back to top

ADVANCES IN SURFACE AND SPRINKLER IRRIGATION

Select this Article		Evaluation of Basin Inflow Cutoff Criterion in the Irrigation Districts of Southwest Arizona D. Zerihun, E. Bautista, T. S. Strelkoff, C. A. Sanchez, A. J. Clemmens, and M. Niblack ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)82 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Low irrigation efficiencies persist in irrigated areas near Yuma, Arizona due to poorly designed irrigation systems, poor condition of existing systems, inaccurate delivery of flow rates, and inadequate criteria for determining irrigation cutoff to individual basins. In farms where growers lack adequate control over the water supplied to individual basins, conventional irrigation cutoff criteria, based on precise measurement of inflow rates, are ineffective. A joint research project, involving the USDA‐ARS‐ALARC, University of Arizona, and the USBR, is exploring the management of these systems using the time of advance to half the field length as a criterion for cutoff when inflow rates are not know accurately. Preliminary simulation studies have shown the potential benefits and limitations of such a strategy. This strategy is being tested in the field, to assess its sensitivity to uncertain system properties. This article describes the general research methodology and some of the initial simulation and field results.

Select this Article		Performance of a Variable Rate Center Pivot System Earl Vories, Phil Tacker, Daniel Stephenson, Sreekala Bajwa, and Calvin Perry ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)83 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract US farmers have access to equipment for variable‐rate application of most inputs, but some potential benefits of precision agriculture may be masked by uniform application of irrigation water. A system developed at the University of Georgia for variable‐rate (VR) water application was installed on a 400‐m long center pivot system at the Judd Hill Plantation in northeast Arkansas. The objective of this research is to monitor the system to determine the potential for water and energy savings. A replicated large‐plot study was initiated in 2006 based on soil mapping units. Application rates were 13, 19, and 23 mm. No significant cotton yield differences were observed in 2006, probably due to rainfall at the site in July and August. Instrumentation installed in 2007 showed a slightly lower water flow rate and increased water pressure when the end gun was shut off, but the fuel flow rate did not change. The water flow rate decreased during the study period and an additional sensor will be added to test for changes in the water table depth. Future studies are planned to repeat the large‐plot study of 2006, monitor the system under a wider range of operating conditions, and investigate possible variable rate nitrogen application through the irrigation system.

Select this Article		Surface Volume Estimates for Infiltration Parameter Estimation E. Bautista, A. M. ASCE, T. S. Strelkoff, A. J. Clemmens, and D. Zerihun ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)84 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Volume balance calculations used in surface irrigation engineering analysis require estimates of surface storage. These calculations are often performed by estimating upstream depth with a normal depth formula. That assumption can result in significant volume estimation errors when upstream flow depth evolves slowly with time and cannot be used under zero‐slope conditions. This article examines the errors incurred when calculating upstream depth with an approximation to the zero‐inertia equation instead of the normal depth formula. The approximation, which uses an empirical adjustment factor, gives reasonable results under a wide range of hydraulic conditions.

Select this Article		The Effects of Geometry and Wetted Perimeter on Surface Irrigation Infiltration Wynn R. Walker ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)85 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract One of the lingering questions in surface irrigation is the relationship between the one‐dimensional infiltration associated with borders and basins and the two‐dimensional infiltration associated with furrows. A corollary question is the effect of flow variations on furrow infiltration. Definitive answers to these questions would resolve several important evaluation and design issues. For instance, if such relationships were known, a simple field evaluation of a furrow would provide much of the data necessary for border and basin design and management. Or, having this relationship would allow a planner to evaluate the comparative advantages and disadvantages of borders, basins, and furrows within the context of the same system. In 2004 the USDA‐NRCS intake families were redefined on the basis of initial furrow irrigations. Later in 2006 the hydraulic properties of these families were determined by parametrically matching HYDRUS 2D (Šimůneck, et al., 1999) simulations to the cumulative infiltration predicted for each family curve. In this paper, the effects of varying wetted perimeter are evaluated in two contexts: (1) how wetted perimeter variations in furrow irrigation can be simulated; and (2) how the two‐dimensional furrow intake can be converted to the one‐dimensional border or basin cases.

back to top

ALTERNATIVE APPROACHES FOR ESTIMATING EVAPOTRANSPIRATION

Select this Article		Estimating the Soil Surface Evaporation and Transpiration Components from Satellite Images in the Absence of a Thermal Band B. Burnett, R. G. Allen, M. ASCE, C. W. Robison, M. Tasumi, M. ASCE, and I. Lorite ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)86 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract With the expected failure of Landsat 5 within the next five years and the likelihood of no thermal sensor on Landsat 8 scheduled for launch in 2011, the prospect of energy balance determination of evapotranspiration (ET) from Landsat scale resolution (30 m) is dim. An alternative to the computation of a full energy balance is to use the presence of vegetation cover, characterized using a vegetation index, to estimate the relative rate of transpiration from a pixel and then add an additional evaporation amount that stems from a wet soil surface. The wet surface is modeled using precipitation and irrigation amounts and weather data. This approach, while lacking accuracy of the full energy balance, provides means to create ET images using short wave reflectances produced by future medium resolution satellites. The relatively simple evaporation model of FAO‐56 is used to compute daily evaporation losses in the context of transpiration from vegetation. These evaporation losses are added to transpiration derived from a vegetation index to produce a complete estimate for ET. Because of the enormous number of pixels in a Landsat scale image (30 million), it is not possible to know specific irrigation timings by field, so that synthetic irrigation events are simulated. Comparisons between synthesized ET from the described approach and ET from a full energy balance computed using METRIC are explored for parts of south central Idaho and error is quantified.

back to top

CROP COEFFICIENTS TO ESTIMATE IRRIGATION WATER REQUIREMENTS

Select this Article		Comparison of Evapotranspiration Images Derived from MODIS and Landsat along the Middle Rio Grande R. G. Allen, M. ASCE, M. Tasumi, M. ASCE, R. Trezza, C. W. Robison, M. Garcia, D. Toll, K. Arsenault, J. M. H. Hendrickx, and J. Kjaersgaard, M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)87 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Landsat images are highly preferred to images by MODIS for producing evapotranspiration (ET) maps for specific land use types because of their higher resolution (30 m). However, Landsat images are potentially available only each 16 days, and, with the expected failure of Landsat 5 within the next five years and the likelihood of no thermal sensor on Landsat 8 scheduled for launch in 2011, the prospect of images from Landsat that are useful for application with energy balance determination of evapotranspiration (ET) is dim. Therefore, more use of coarse resolution satellite images, such as 1 km thermal images from MODIS, will occur. One advantage of MODIS satellites is that images having view angle < ∼15° are potentially available about each four to five days. Application of METRIC energy balance processes along the Middle Rio Grande of New Mexico using MODIS imagery indicates that one can successfully reproduce monthly and annual ET estimates that were obtained using Landsat imagery. However, spatial fidelity is highly degraded. This paper compares ET images for the Rio Grande region as produced by both MODIS and by Landsat.

Select this Article		Evapotranspiration of Corn and Forage Sorghum for Silage T. A. Howell, S. R. Evett, J. A. Tolk, K. S. Copeland, P. D. Colaizzi, and P. H. Gowda ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)88 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract In the U.S. Southern High Plains, dairies have expanded and have increased the regional demand for forage and silage. The objectives were to measure water use and determine crop coefficients for corn (Zea mays L.) and forage sorghum (Sorghum bicolor (L.) Moench) produced for silage on the Southern High Plains. Water use was measured with large, precision weighing lysimeters in 2006 and 2007. Both growing seasons had normal to above normal rainfall. The 2006 season was more advective with greater mean daily reference evapotranspiration (ET) rates. Seasonal ET was 671 mm for forage sorghum with a yield of 1.48 kg m⁻² in 2006 and 489 mm in 2007 with a yield of 1.70 kg m⁻²; water productivity was 2.21 kg m⁻³ in 2006 and 3.47 kg m⁻³ in 2007. Seasonal ET was 418 mm for corn for silage with a yield of 1.52 kg m⁻² in 2006 and 671 mm in 2007 with a yield of 2.44 kg m⁻²; water productivity was 3.63 kg m⁻³ in 2006 and 3.64 kg m⁻³ in 2007. Using the 2007 season as a better species comparison, forage sorghum can achieve comparable water productivity as corn with less ET (∼73% of corn ET) and irrigation requirement although with a reduced yield (∼62% of corn dry matter).

Select this Article		Hourly Reference Evapotranspiration Estimates for Alfalfa in North Dakota Xinhua Jia, Dean D. Steele, and David Hopkins ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)89 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract When many places in the world are facing water scarcities, the Devils Lake basin in northeastern North Dakota has received above normal inflow due to excess rainfall since 1993. A research project is being conducted to determine the extent to which irrigation can utilize some of the excess surface waters in the basin without impairing the productivity of soils, many of which are classified as only conditionally irrigable. Understanding of the evapotranspiration (ET) process is critical for irrigation application, but ET research is generally lacking in this region. The sub‐humid continental climate in North Dakota has high variations in hourly, daily, seasonal, and annual ET rates. The soil normally stays wet in the early growing season. Irrigation is needed in the mid‐growing season when crops are also in a critical stage for supplemental water. In this study, hourly reference evapotranspiration rates for alfalfa were examined by the ASCE EWRI Penman‐Monteith method. The weather data used in the calculations were collected from a 42‐ha alfalfa field located in Benson County, North Dakota. Thirty minutes values, including air temperature, relative humidity, solar radiation, and wind speed were measured and average hourly values were used in the reference ET calculations. The evaluation and comparison among the daily and sum of 24 hour reference ET provided a good assessment on the highest amount of water that could be potentially used by agricultural crops in the Devils Lake area.

Select this Article		Surface Energy Balance and Surface Coefficients of a Corn Field during Non‐Growing Periods Christopher H. Hay, A. M. ASCE and Suat Irmak, M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)90 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Efficient use of water in agroecosystems requires accurate quantification of evapotranspiration (ET) during growing and non‐growing (dormant) periods. Prediction of ET during the growing season has been well researched, but relatively little information exists on evaporative losses during non‐growing periods. The objective of this research was to evaluate ET in relation to available energy, precipitation, and reference ET for a corn field during the non‐growing period (October 15 through April 30). Three consecutive non‐growing periods were studied: 2004–2005 (season I), 2005–2006 (season II), and 2006–2007 (season III). Bowen ratio energy balance system‐measured ET was approximately 50% of available energy during average and wet seasons (seasons I and III) and 41% of available energy during a dry season (season II). Cumulative ET ranged from 133 to 167 mm and exceeded precipitation by 21% during the dry season. Mean surface (crop) coefficients were 0.63 and 0.48 for grass and alfalfa‐reference crops, respectively. Regression equations were developed that yielded reasonable estimates of ET for the average and wet seasons. Considering non‐growing period evaporative losses in water budget calculations would enable water regulatory agencies to better account for water use over the entire year rather than only for the growing season.

back to top

DEVELOPMENT AND MANAGEMENT OF IRRIGATION PROJECTS

Select this Article		A Review of Evolving Critical Priorities for Irrigated Agriculture P. D. Colaizzi, R. D. Bliesner, and L. A. Hardy ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)91 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The evolving roles and critical priorities of irrigated agriculture, as perceived by practitioners, researchers, and policy makers, were reviewed. Irrigated agriculture has played a vital role in meeting food and fiber demands on a relatively small proportion of total arable land. This role is presently expanding to also include biofuel and industrial materials production. At the same time, water availability is almost universally declining where intensive irrigation has been developed. This has been mainly due to declining water resources, inadequate storage capacity, or greater competition from non‐agricultural uses. Although certain priorities may be specific to a location or region, the unifying priorities for irrigated agriculture, in order to meet unprecedented demands by a worldwide population that is increasing both in size and in industrialization, are to increase water productivity, sustain ecosystems, find synergy and avoid conflict among agriculture, urban and environmental uses of water resources.

Select this Article		Analysis of the Effects of Best Management Practices Implemented within the Belle Fourche Irrigation District Jared K. Oswald ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)92 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The Belle Fourche River is a natural stream that drains parts of Butte, Lawrence, and Meade Counties in South Dakota with the headwaters located in Wyoming. The river flows into the Cheyenne River in southern Meade County and ultimately to the Missouri River. The Belle Fourche River Watershed in South Dakota is approximately 2,100,000 acres (3,300 square miles) in size. The Belle Fourche River and Horse Creek, a tributary, are identified in the 1998 and 2002 South Dakota 303(d) Waterbody Lists and the 2004 and 2006 Integrated Report for Surface Water Quality Assessment as impaired because of elevated total suspended solids (TSS). A TSS Total Maximum Daily Load (TMDL) was approved by the Environmental Protection Agency in 2003 for both streams. The Belle Fourche Irrigation District (BFID), identified in the TMDL as a significant contributor to TSS loading, delivers water to 57,183 acres of farmland through its 94 miles of open main channel and 450 miles of open lateral ditches. This paper will discuss the complete water management system that was developed for the BFID. This system was designed to reduce the amount of sediment‐laden flows entering the streams by increasing the overall delivery efficiency of the BFID. The components of this management system include automated check structures, head gates, and flow‐measuring devices along the main canals and laterals; software to automate the water order and billing system; water master software to calculate a water mass balance needed to support water orders and compare to actual measurements; software to automate the water order and billing system; and Web‐based irrigation scheduling software. Many of the automated structures are connected via radio network to the BFID headquarters, which allows personnel to monitor and control settings in real‐time. Before the development of the complete water management system, the BFID operated the canals manually and performed all calculations to determine water orders, water billing, and water mass balance by hand. This was extremely labor‐intensive and led to inefficiencies in the transport of the water from the dam to the farmer's fields. The new water management system provides timely information to support the decision‐making process. The system allows BFID personnel to assess and manage the entire system to better offset fluctuations in deliveries caused by rainfall, heat, or equipment malfunctions while substantially reducing the amount of time and effort required to perform their daily tasks.

Select this Article		Economic Optimization of Groundwater Resources: A Case of Texas County in Oklahoma Panhandle Lal K. Almas and W. Arden Colette ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)93 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract An economic optimization model for a sixty years planning horizon is developed using available groundwater resources in the Texas County of Oklahoma Panhandle. Net present value and total water use over 60 years is used to estimate the value of water for irrigated agriculture in the area. The model will serve as a policy tool to analyze alternative water management strategies and water conservation programs that can possibly be implemented in the area. The results from the model will also be used to assess the economic impact of depleting groundwater availability from the Ogallala Aquifer. The economic optimization model can be used to analyze alternative policy scenarios such as change in corn prices due to ethanol production, water pumping restriction and incentives to producers for management practices to be used for water conservation.

Select this Article		Irrigation Water Conservation and Transfer: The Imperial Irrigation District Experience John T. Eckhardt, Ph.D., P.E., Grant G. Davids, P.E., and Ronald D. Bliesner, P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)94 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Water use in the West is changing, and nowhere is that being felt as acutely as the Imperial Irrigation District, a 450,000‐acre, 12‐month growing season district in Southern California where longstanding agricultural water users are under intense pressure to transfer water to the region's ever‐thirsty and ever‐expanding urban areas. In 2003, the District entered into 37 transfer agreements (IID, 2007), referred to collectively as the Quantification Settlement (QSA) and related agreements. The QSA committed the District to a massive efficiency conservation program that would free up roughly 10 percent of its water for transfer to San Diego and others. The heart of the QSA calls for the District to generate more than 300,000 acre‐feet of water through a combination of District and voluntary on‐farm efficiency conservation savings. In 2007, IID completed their Efficiency Conservation Definite Plan (Definite Plan) that outlined strategies for both delivery system and on‐farm water savings. The pertinent terms of the water transfer agreements and their implication to development of the Definite Plan are discussed and the elements of the Definite Plan are presented. The paper concludes with an assessment of lessons learned and discussion of key technical and other issues encountered.

back to top

ET ESTIMATION USING REMOTE SENSING: II

Select this Article		Calibration of GOES‐Derived Solar Radiation Data Using a Distributed Network of Surface Measurements in Florida, USA David M. Sumner, Chandra S. Pathak, John R. Mecikalski, Simon J. Paech, Qinglong Wu, and Taiye Sangoyomi ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)95 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Solar radiation data are critically important for the estimation of evapotranspiration. Analysis of visible‐channel data derived from Geostationary Operational Environmental Satellites (GOES) using radiative transfer modeling has been used to produce spatially‐ and temporally‐distributed datasets of solar radiation. An extensive network of (pyranometer) surface measurements of solar radiation in the State of Florida has allowed refined calibration of a GOES‐derived daily integrated radiation data product. This refinement of radiation data allowed for corrections of satellite sensor drift, satellite generational change, and consideration of the highly‐variable cloudy conditions that are typical of Florida. To aid in calibration of a GOES‐derived radiation product, solar radiation data for the period 1995–2004 from 58 field stations that are located throughout the State were compiled. The GOES radiation product was calibrated by way of a three‐step process: 1) comparison with ground‐based pyranometer measurements on clear reference days, 2) correcting for a bias related to cloud cover, and 3) deriving month‐by‐month bias correction factors. Pre‐calibration results indicated good model performance, with a station‐averaged model error of 2.2 MJ m⁻² day⁻¹ (13 percent). Calibration reduced errors to 1.7 MJ m⁻² day⁻¹ (10 percent) and also removed time‐ and cloudiness‐related biases. The final dataset has been used to produce Statewide evapotranspiration estimates.

Select this Article		Comparing SEBAL ET With Lysimeter Data in the Semi‐Arid Texas High Plains P. H. Gowda, T. A. Howell, J. L. Chavez, K. S. Copeland, and G. Paul ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)96 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract SEBAL (Surface Energy Balance Algorithm for Land), a spatial evapotranspiration (ET) estimation method, has been applied with Landsat Thematic Mapper (TM) data throughout the world. However, it has never been tested for semiarid conditions of the Texas High Plains. In this study, SEBAL algorithm was applied to a Landsat TM image acquired on July 10, 2007 covering a major portion of the Texas High Plains. Performance of SEBAL was evaluated by comparing estimated ET with measured ET data on four large monolithic lysimeters at the USDA‐ARS Conservation and Production Research Laboratory, Bushland, TX. Comparison of SEBAL‐estimated instantaneous ET values with lysimetric measurements indicated that SEBAL may provide better ET estimates for irrigated fields. However, it performed poorly in predicting ET for fields under dryland management. This result may indicate that SEBAL might be sensitive to errors in the selection of the hot/dry pixel. Overall, SEBAL is a promising tool for mapping ET in the extensively irrigated Texas High Plains. However, more evaluation is needed for different agroclimatological conditions in the region.

Select this Article		Computation of Landsat Based Evapotranspiration Maps along the South Platte and North Platte Rivers J. H. Kjaersgaard, R. G. Allen, G. R. Aggett, C. A. Schneider, M. J. Hattendorf, A. Irmak, G. W. Hergert, and C. Robison ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)97 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract It is important to quantify the consumptive water use by the vegetation when managing regional water resources in irrigated areas. Suitable models and algorithms applied to high resolution (30 m) satellite imagery provide a cost effective and time efficient method to obtain evapotranspiration estimations from bare soil and vegetation. The METRIC image processing model calculates net radiation, soil heat flux and sensible heat flux through a number of steps before estimating evapotranspiration as the residual from the energy balance. Sensible heat flux algorithms are calibrated using an operator selected wet and dry pixel. The complete energy balance obtained from the satellite images is calibrated using ground based reference evapotranspiration estimations. The paper describes an application of the METRIC model on parts of the South Platte and North Platte rivers in Colorado and Nebraska for individual days in 1997, 2001 and 2002. Landsat 5 and Landsat 7 shortwave and longwave bands were used. Weather data from selected meteorological stations within the study area was screened and used to estimate reference evapotranspiration. A water balance model was used to estimate evaporation from the soil. During the image processing it was necessary to iterate the selection of the wet and dry pixels after reviewing evapotranspiration behavior for natural vegetation and wet fields at full cover. Uneven distribution of recent precipitation events and operator dependency needed to be addressed. The resulting evapotranspiration maps appear to be congruent with ET from previous studies and will be used by local water management entities.

Select this Article		Enhanced Resolution of Evapotranspiration from Riparian Systems and Field Edges by Sharpening the Landsat Thermal Band R. Trezza, R. G. Allen, M. ASCE, C. W. Robison, W. J. Kramber, J. Kjaersgaard, M. ASCE, M. Tasumi, M. ASCE, and M. Garcia ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)98 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Evapotranspiration (ET) is the major consumptive use of irrigation water, and thus, spatial and temporal quantification of ET is important to agricultural water management. In water rights management and precision irrigation, information on ET is desirable on a field or subfield scale. Therefore, fine resolution satellite imagery and ET products derived from the satellite imagery are highly desirable. However, for a majority of satellites, spatial resolution of the longwave (thermal) band(s) is coarser than the coincident shortwave bands, which creates a compatibility and correspondence issue for the data used for energy balance (EB) and increases the net pixel resolution and reduces fidelity of ET calculations. Typically, surface temperature (T_s) and vegetation indices (VI) are closely correlated, especially under conditions of high availability of soil water, due to the effects of evaporative cooling by vegetation, especially some days after wetting events, when the exposed soil surface is dry and warm relative to vegetation. This physical relationship can be exploited to sharpen T_s using VI if the assumption of cooled surface by vegetation holds. This paper describes a technique developed for application with the METRIC and SEBAL EB procedures that uses the concept of hot and cold thermal conditions associated with dry and wet surface conditions during calibration as a means to distribute T_s at a subpixel scale using subpixel VI. The result is an image of T_s that has the same spatial resolution of the short wave images. Therefore, the resolution of ET images created during the METRIC or SEBAL processes can have equally high resolution. Applications made in Idaho and New Mexico using sharpened thermal imagery are described.

Select this Article		Multiple Satellites Remote Sensing Images for the Derivation of a Water Availability Index Ni‐Bin Chang, Y. Jeffrey Yang, James A. Goodrich, and Steven G. Buchberger ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)99 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Recent drought events in the U.S. have threatened drinking water supplies for communities in Maryland and Chesapeake Bay in 2001 through September 2002, Lake Mead in Las Vegas in 2000 through 2004, the Peace River and Lake Okeechobee in South Florida in 2006, and Lake Lanier in Atlanta, Georgia in 2007. In the environmental science community, there is a renewed interest to develop a new “Water Availability Index (WAI)” that serves for short‐term water resources planning and water infrastructure management in dry periods. Such a development may be geared toward presenting a near real‐time, risk informed and forward‐looking instrumental message in terms of both the quantity and quality of available fresh water in major metropolitan regions. The success of this effort could incorporate the use of integrated remote sensing technologies in concert with intermediate‐ and long‐term climate change forecasts. It is the aim of this paper to present a state‐of‐the‐art review about: 1) How the multi‐scale and multi‐dimensional databases are collected by optical and microwave satellite images, such as the NASA GOES, MODIS Terra and Aqua etc., and ground‐based radar stations, such as the NOAA NEXRAD system, and 2) How these databases can be applied to support the development of a new WAI and help reduce the managerial risks of water infrastructure across the continental U.S. These discussions lead to the derivation of a new WAI with the aid of remote sensing technology.

back to top

IRRIGATION CANAL AUTOMATION AND MANAGEMENT

Select this Article		Identification of Pool Characteristics of Irrigation Canals P. J. van Overloop, I. J. Miltenburg, A. J. Clemmens, and R. J. Strand ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)100 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract In the Western part of the United States of America, more and more irrigation canal networks are being modernized, which often includes some form of real‐time automatic water level control. This real‐time control consists of water level measurements that are communicated to a controller. The controller calculates the required control actions and communicates these back to the adjustable gates. The objective of the controller is to maintain the water levels in the canal pools at a given target level. The control loop is repeated at a fixed time interval. To attenuate noise and undesired signal contents, filtering of the water level measurements is required. The reasons that irrigation districts decide to automate their canals include: improved water delivery service, improved efficiency of water delivery, improved utilization of labor, and water resource stewardship. The design of a water level controller is not obvious. On one hand, the reaction to flow disturbances or changes in target level should be fast. On the other hand, tuning the controller to react too strongly to these disturbances can result in overreaction and water levels that severely oscillate. Research on control of open channels has resulted in design (tuning) rules for water level control and filtering that are based on estimates of certain pool characteristics. These characteristics are the storage area of the back water part of the pool, the delay time from upstream side to downstream end and for short, flat and deep pools the frequency and peak magnitude of the basic reflecting wave (resonance) as well. This article presents a procedure to determine the pool characteristics required for controller and filter design. The procedure applies system identification tools and was tested on several canal pools at the Central Arizona Irrigation and Drainage District, Eloy, AZ. The identification procedure results in realistic characteristics for the pools.

Select this Article		Impact of Canal Design Limitations on Water Delivery Operations and Automation A. J. Clemmens and R. J. Strand ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)101 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Irrigation canals are often designed for water transmission. The design engineer simply ensures that the canal will pass the maximum design discharge. However, irrigation canals frequently operated far below design capacity. Because demands, and therefore the distribution of flow at bifurcations (branch points), can vary from day to day, or even from hour to hour, to meet user demands, the hydraulic grade line of the canal can vary significantly over the range of flows encountered. This complicates the operator's job of distributing flow to users. Common problems include; insufficient head at low flows for turnouts in the upper end of pools, gates that transition from free to submerged flow over the range of conditions, culverts that greatly change the pool volume over the range of discharges due to backwater effects, canal gates that are oversized for safety which limits small discharge changes, variable backwater conditions that compromise flow measurement devices (both in pipes and channels), incompatible hardware for automated control of check gates, etc. Examples from canal systems in Central Arizona are given with options for improving operations. This quote from an irrigation district engineer says it best “Design engineers should be forced to operate the canal systems that they design.”

Select this Article		Impacts of Shear Stress on Saturated Hydraulic Conductivity of a Polyacrylamide Treated Soil Mark C. Stone, John O. Goreham, Li Chen, and Asako B. Stone ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)102 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Polyacrylamides (PAMs) have been historically used in industrial and environmental settings in food packaging, paper manufacturing, waste water treatment, and soil loss prevention. Recently, PAM has been considered for use in unlined earthen irrigation canals to reduce seepage losses. To evaluate the potential benefits and risks associated with PAM applications to irrigation canals, a series of studies have been conducted by the Desert Research Institute (DRI) in collaboration with the US Bureau of Reclamation (USBR). The purpose of this research was to investigate the impacts of shear stress on soil hydraulic conductivity of a PAM treated soil. A small experimental flume was built to accommodate four soil columns attached to its bed. The soil columns were filled with engineered sand and treated with three PAM concentrations and a control (no PAM). Water flux and K_sat were measured through the soil columns over a period of several hours. Experiments were completed for three flowrates and a control (no flow). Four major conclusions were drawn from the experimental results: 1) a reduction in water flux was observed as a function of PAM concentration; 2) when the PAM application was free of imperfections, the PAM layer was resistant to shearing; 3) imperfections in the PAM layer (e.g. bubbles or rips) caused a substantial increase in water flux; and 4) failure of the PAM layer occurred abruptly and was highly variable, although typically associated with a flaws in the PAM layer.

Select this Article		SCADA Operator Training Tool Applied to the Central Arizona Irrigation and Drainage District Brian Wahlin, M. ASCE, Robert Strand, Christopher Goodell, M. ASCE, Albert Clemmens, M. ASCE, and Nathan Denny ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)103 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Many irrigation districts use Supervisory Control and Data Acquisition (SCADA) software to manage their canal systems. Whether homegrown or commercial, these programs require a significant amount of training for new operators. While some SCADA operators are hired with extensive field experience, others are hired with no field experience at all and require extended training to gain an understanding of the behavior of open‐channel systems. Regardless of their experience, these operators usually receive SCADA training while managing the actual canal system and thus their training is driven by the day‐to‐day operation of the system. The SCADA operators receive no hands‐on training for emergency situations such as hardware vandalism, large storm events, or a canal breach. Creating these emergency situations in a canal system for training purposes leads to wasting water, causing significant fluctuations in water levels in the adjoining pools, or potentially causing severe damage to the canal system. Recently, researchers at the U.S. Arid Land Agricultural Research Center created a training tool that replaces the real canal with a hydraulic simulation model without making any changes to the SCADA software. Employees at WEST Consultants, Inc. recently modified this training tool so that it works with HEC‐RAS as the hydraulic simulation model. Using this system, SCADA operators can be trained to operate a canal system under a wide range of emergency situations without endangering the actual canal system or wasting water. This type of training should reduce the time required to train operators, allow the SCADA operators to route flow changes more efficiently through the system, and give operators a larger knowledge base with which to handle emergency situations. This training tool was recently applied to the Central Arizona Irrigation and Drainage District in Eloy, Arizona. Because of the flexibility and applicability of this training tool, we hope that this tool can be used in a wide range of training situations.

back to top

IRRIGATION MANAGEMENT WITH LIMITED WATER

Select this Article		A Feedback System to Optimize Crop Water Use Estimates in Irrigation Scheduling Marshall English, Chadi Sayde, Alix Gitelman, and Laureine El Khoury ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)104 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract This paper deals with errors in estimation of soil water depletion inirrigation management. Such errors can reduce net economic returns to water, increase economic risk and motivate risk averse farm managers to adopt less profitable strategies. Two common methods of estimating depletion are discussed, one based on cumulative ET the other on soil moisture measurements. Both are characterized by significant uncertainty. It is common practice to rely on one or the other of these estimators for irrigation scheduling. This paper proposes an alternative approach that utilizes both estimators in combination. Rather than treating them as deterministic quantities, they are treated as random variables. The probability distributions of each are combined in a Bayesian analysis to derive a probability distribution of depletion, which then provides a better basis for irrigation decisions.

Select this Article		Cotton Production Potential and Water Conservation Impact Using the Regional Irrigation Demand Model of Northern Texas Thomas Marek, Dana Porter, Terry Howell, Prasanna Gowda, Paul Colaizzi, Steve Amosson, and Fran Bretz ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)105 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Revised irrigation demands are calculated for the 21 northernmost counties in Texas, identified as Region A, using the TAMA (Texas A&M—Amarillo) agricultural water use demand estimation model. Year 2000 demands are presented using the existing mixture of crops, average evapotranspiration values and actual irrigation application practice values. Current demand values are expected to exceed the allowable water supply in several, intensively irrigated counties within the region. Thus, the alternative, lower water use crop of cotton is evaluated in terms of substitution potential for the presently produced, more intensive water use crop of corn. Although cotton has significant, differing production requirements in northern Texas, successful production has been documented within the region at the North Plains Research Field (NPRF) and average yield parameters are presented. The water savings impact of converting percentages of county acreages from corn to cotton is reported and discussed. The water conservation impact to the Ogallala aquifer is calculated over the region's current 60‐year planning horizon. The potential impact of recent ethanol demands is briefly discussed.

Select this Article		Deficit Irrigation of Corn in a No‐Till Environment Norman L. Klocke, P.E., M. ASCE, Randall S. Currie, and Loyd R. Stone ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)106 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A field study was conducted near Garden City, Kansas to measure corn grain yield response to a range of rates from full to deficit irrigation. The contributions of antecedent stored soil water to crop water use were determined from soil water measurements near the beginning and the end of the growing season. Above average winter precipitation contributed to pre‐plant soil water accumulations and deficit irrigation caused more growing season stored soil water use. Field results were compared with the Crop Water Yield (CWY) predictions of field results. Correlation of relative yields from field results and the CWY simulation were good, showing that the CWY has potential to be used as a management tool to screen potential irrigation scheduling scenarios for deficit irrigation.

Select this Article		Using a System Model to Maximize Water Use Efficiency through Optimizing Management Inputs and Scheduling of Limited Irrigations for Site‐Specific Weather and Soil Conditions L. R. Ahuja, S. A. Saseendran, L. Ma, D. C. Nielsen, and T. Trout ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)107 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Most of the agriculture in the Great Plains and western U.S. is water‐limited, consisting of rain‐fed, dry‐land, cropping systems or range‐livestock systems and some irrigated cropping systems where irrigation water is available. Prolonged drought in the last few years has aggravated the situation, and greater frequency of severe droughts predicted by global climate change models is a cause for great concern, especially for dry‐land systems. At the same time, the increasing water demands for drinking, sanitation, urban irrigation, industry, and environmental uses are outbidding and reducing the irrigation water available for agriculture. Similar situation exists in many other arid to semi‐arid parts of the world. To obtain maximum return out of limited rainfall and irrigation water, with minimum environmental impact, the producers need whole‐system and quantitative management tools to help them optimize the use of available water and minimize associated inputs on site‐specific and field‐specific basis. The tools should help determine appropriate crop sequences, and optimize the use of limited rainfall and irrigation water with respect to the amounts and timings of rainfall, critical growth stages of crop, soil fertility, and weather conditions; help determine an optimal selection of alternate crops during droughts; and an optimal allocation of limited water among crops. There is currently great excitement about growing bio‐energy crops in the area, including the dry‐land oil seed crops and irrigated corn or other biomass crops. The above tools should also be able to evaluate the long‐term economics of bio‐energy crops while leaving enough crop residues on the soil to maintain soil organic matter.

Select this Article		Using Climatic Data and Evapotranspiration Requirements to Estimate Corn Production Profitability with Optimal Irrigation Levels in the Texas Panhandle W. Arden Colette, Lal K. Almas, and Clay Robinson ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)108 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The performance of the agricultural sector in the Texas Panhandle is dependent on irrigation. The declining availability of irrigation water from the Ogallala aquifer combined with increasing energy costs make irrigation strategies much more critical. Economic viability and resource conservation are not mutually exclusive. Selecting an irrigation level maximizes profits both increases profits and conserves the water resource as compared with a strategies of maximizing yield per acre. Under average precipitation, a management strategy that irrigates to maximize yield reduces profit by between $22 and $158 per acre and increases water consumption by 2.21 and 11.20 acre inches depending on the combination of corn and natural gas prices. Adopting a profit maximizing strategy is a win‐win situation both economically and for water resource conversation.

back to top

MANAGEMENT ALTERNATIVES TO IMPROVE DRAINAGE WATER QUALITY

Select this Article		Effects of Animal Waste Regulations on Drainage Water Quality: An Example of Adaptation Strategies for Sustainable Agriculture T. Kato, M. Tamura, and H. Ohta ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)109 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract In Japan, the “Law on promoting proper management and use of livestock excreta” (animal waste regulations) was implemented nationwide in November 2004; this law prohibited the disposal of animal wastes in earthen storage ponds. To examine the effects of this law, a 2‐year daily analysis of water quality and hydrology of a drainage canal of an agricultural area with intensive livestock production in the Lake Kasumigaura Basin, Japan, was conducted from November 2003 to October 2005. The water quality indices were total nitrogen, nitrate nitrogen, ammonium nitrogen, total phosphorus, and chemical oxygen demand. Considering daily precipitations during the irrigation and non‐irrigation periods, both the concentrations of pollutants and effluent loads were compared between the prelaw and postlaw periods. The results suggested that the amount of effluent loads from animal wastes to drainage decreased after the enforcement of this law and that animal waste regulations were among the most effective local adaptation strategies for reducing effluent loads from agricultural areas.

Select this Article		Relationship between Farming Activities and Water Quality Variations of Drainage Water from Paddy Fields Area Hiroaki Somura, Ikuo Takeda, and Yasushi Mori ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)110 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract We paid attention to relationship between farming activities and changes in drainage water quality from a paddy fields area, especially in land preparation period for transplanting of paddy. Drainage water quality during land preparation period became highest concentration of all items through a year. In 2006, average water qualities in the period were 7.9 mg/L in T‐N, 1.6 mg/L in T‐P, 15.3 mg/L in TOC, and 372 mg/L in SS. In addition, maximum values in the period were 36.2 mg/L in T‐N, 12.3 mg/L in T‐P, 83.2 mg/L in TOC, and 3020 mg/L in SS. The changes in water quality moved on with land preparation by tractor and drainage gate operation on each paddy field by farmers. Moreover, relatively high concentrations of drainage water were also observed during non‐irrigation period. As no agricultural activities were done during the period, it is considered that residual nutrient in soil will infiltrate by rain water and flow to the drainage channel.

Select this Article		Sediment Management Technique for Agricultural Watershed K. Osawa, S. Ikeda, and K. Noda ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)111 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Soil erosion and runoff have led to agricultural and environmental problems throughout the world. Therefore effective measures which can reduce sediment yield in the farmland are necessary. For the purpose, advanced sediment management technique is required. A study area is Nagura‐river watershed, Ishigaki Island, Japan. GIS for sediment management in watershed was constructed. Consequently, multi‐points observation was carried out at six points in the watershed. In these studies, a soil erosion and sediment runoff model was constructed and tested to verify their applicability in predicting sediment yield and sediment runoff. The calculated sediment runoff by the model was in approximate agreement with the observed. In the present application to the watershed sediment management, the authors carried out some case studies to choose proper combination of sediment yield reduction measures. The calculation has shown that sediment runoff at outlet of the watershed can be reduced by 12% if the measures about land deformation are taken into consideration. Another calculation has shown that sediment runoff can be reduced by 74% if the combination of measures about land deformation and about farming program is properly chosen.

back to top

MANAGEMENT OF IRRIGATION SALINITY AND ET ESTIMATION USING REMOTE SENSING I

Select this Article		Estimation of Land Surface Energy Fluxes: An Application of Satellite Remote Sensing Procedure Ayse Irmak ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)112 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Surface energy fluxes, including sensible heat, latent heat, net radiation, and soil heat flux, play crucial role in surface energy dynamics of any terrain or landscapes. Estimation or measurement of these energy fluxes is critical for completing the water balance in terrestrial ecosystems, and therefore accurately predicting the effects of global climate and land use change. There are various methods available for ET estimation. Bowen ratio energy balance and eddy correlation techniques offer powerful alternatives for measuring land surface energy fluxes. In spite of the elegance, high accuracy and theoretical attractions of these techniques for measuring ET, their practical use over large areas can be limited. These techniques provide measurements at a point scale and may not be practical when quantifying water use over large areas due to the number of measurement sites needed and the operational expense of such a dense network. Application of ET mapping from satellite measurements can overcome aforementioned limitations. The objective of this study is to assess the performance of the METRIC™ (Mapping Evapotranspiration at high Resolution using Internalized Calibration) model for estimating land surface energy fluxes to improve our understanding of processes that govern water use in managed and native ecosystems in south‐central Nebraska.

Select this Article		Irrigation Management Considerations When Using Reuse Water on Golfcourses in the Arid Southwest D. A. Devitt ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)113 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Proper irrigation management is critical when using poor quality water such as reuse water on golf courses in the arid southwestern United States. Results from multiple studies conducted by this author are reviewed and reported on in this paper. A survey of golf course superintendent's attitudes and perceptions toward using reuse water revealed little opposition to using reuse water but a realization that using reuse water can negatively impact golf course operations. Key irrigation management factors are discussed that can significantly alter the ability of a superintendent to maintain a healthy productive turfgrass stand when using reuse water. The quality of reuse water varies from region to region and superintendents need to have real time water quality analysis to successfully maintain favorable water, nutrient and salt balances. Golfcourses also contain a significant amount of trees, shrubs and flowering annuals in which care must be taken to minimize foliar application of reuse water. Because in the future golfcourses in the arid southwest may face the challenge of being forced to deficit irrigate with reuse water, it is critical that the golf course industry be proactive toward this challenge. It is this author's opinion that golfcourses need to shift toward precision agriculture. This will require not only using weather based and soil based information but also cutting edge technology based on remote sensing.

Select this Article		Moisture and Nitrate Variation in Electrochemically‐Controlled Drip Irrigation System in Sandy Soil Naglaa Eid and Walid Elshorbagy ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)114 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Salt accumulation in soils of arid areas is usually attributed to the quality of irrigation water, soil characteristics, type of irrigation system, and the current irrigation practices. The buildup of salts in the root zones can adversely impact the crop production. The addition of chemicals to crops is a common cause of groundwater contamination as chemicals are usually applied in conjunction with irrigation. Over application of irrigation water can transport chemicals into underlying aquifers and render them unfit for human consumption. In United Arab Emirates “UAE”, most of the irrigation water is applied using drip irrigation systems. This study presents the experimental results of electro‐kinetic method applied to manage the nitrate migration under variable saturation conditions in sandy soil representative of the UAE conditions. The nitrate is considered here as a representative of the nitrogen existing in the utilized fertilizers. A number of experiments were conducted evaluating the system performance subjected to different conditions. These included level of soil compaction, soil washing, and levels of applied currents. The results show that the electro‐kinetic process was efficient in retaining and concentrating the soil nitrate near the anode. Observations and analyses of the results are discussed to better understand the salts electro‐migration under the impact of investigated conditions.

back to top

NEW APPROACHES TO IRRIGATION SCHEDULING

Select this Article		Estimation of Actual Evapotranspiration Using Measured and Calculated Values of Bulk Surface Resistance V. H. Ramirez Builes, E. W. Harmsen, and T. G. Porch ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)115 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The Penman‐Monteith model (PM) is a useful “one‐step” method for evapotranspiration (ET) estimation, if surface resistance (r_s‐ms⁻¹) estimates can be derived. This study has as its objective to evaluate different methods of r_s estimation and the accuracy of the resulting ET estimates in common bean (P. vulgaris L.). The experiment was conducted at the Fortuna Agricultural Experiment Station at Juana Diaz, PR. Four automated weather stations were placed in plots planted with two genotypes of common bean (Phaseolus vulgaris L.). Net radiation, soil heat flux, soil temperature, soil moisture, air temperature, relative humidity, wind speed and direction were recorded at ten second intervals. Each weather station had an elevator system that moved the air temperature and relative humidity sensor between two vertical positions over the crop canopy every two minutes during a complete day. The r_s was derived by stomatal resistance (r_L) and leaf area index (LAI) measurements (PM‐1), and by direct micrometeorological variables as follows: inverse of the general PM‐model (PM‐2), as a function of the soil moisture (PM‐3), and as a latent heat flux‐λE (PM‐4 and ET‐Station). The results indicate that PM‐1 under‐estimated r_s at low LAI, and that r_s and r_L are influenced inversely by the aerodynamic resistance (r_a), which affected the precision of the PM‐2 and ET station estimation especially under windy and dry conditions, but not the PM‐3 and PM‐4 methods.

Select this Article		Evaluation of a Two‐Layer Model to Estimate Vine Transpiration and Soil Evaporation for Vineyards Samuel Ortega‐Farias, M. ASCE, Carlos Poblete, and Mauricio Zuñiga ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)116 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The two‐layer model of Shuttlerworth and Wallace (SW) was evaluated to estimate vine transpirationa (T_sw) and soil evaporation (E_sw) from a drip‐irrigated Merlot vineyard, located in the Talca Valley, Region del Maule, Chile (35° 25′ LS; 71° 32′ LW; 136m above the sea level). An automatic weather system was installed in the center of the vineyard to measure air temperature, relative humidity, wind speed, solar radiation and latent heat flux during January 2007. Values of T_sw and E_sw were compared to sap flow and microlysimeter measurements, respectively. Also, vineyard evapotranspiration (ET_sw) computed by the SW model was evaluated using latent heat flux measurements obtained from an eddy‐covariance system on a 30 minute time interval. Results indicated that SW model was able to predict vineyard evapotranspiration with a root mean square error (RMSE) of 0.3 mm day⁻¹. Also, SW model predicted soil evaporation and vine transpiration with RMSE of 0.2 and 0.8 mm day⁻¹, respectively. In general, the SW model tended to underestimate transpiration and vineyard evapotranspiration, and overestimate the soil evaporation.

Select this Article		Evaluation of Evapotranspiration‐Based and Soil‐Moisture‐Based Irrigation Control in Turf Garry L. Grabow, Arjun Vasanth, Dan Bowman, Rodney L. Huffman, and Grady L. Miller ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)117 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A study was initiated in Fall 2006 in Raleigh, North Carolina to compare two types of commercially available irrigation control technologies, one based on estimates of evapotranspiration (ET) and the other based on feedback from soil moisture sensors. Water applied and turf quality from one ET‐based system and two sensor‐based systems were compared to a system using a standard time‐based irrigation schedule. The effect of irrigation frequency was also a part of the study. Estimates of turf ET were obtained from the Penman‐Monteith equation using on‐site weather data, and also from an atmometer. Results from the twenty week evaluation in 2007 showed that on average the “add‐on” soil‐moisture‐based system evaluated applied the least amount of water while the ET‐based system evaluated applied the most water. Weekly irrigation frequencies used the least amount of water, followed by bi‐weekly and daily frequencies in increasing amounts when averaged across all technologies. Minimally acceptable turf quality was maintained by all technologies and frequencies through most of the study, but turf quality declined substantially the last month of the study for the add‐on system and standard timer‐based system. The “on‐demand” sensor‐based system resulted in the best combination of water efficiency and turf quality.

back to top

BEACH WATER QUALITY/SUSTAINABLE WATER RESOURCES FOR DEVELOPING REGIONS

Select this Article		Clearance of Beach Water Contamination After 48 Million Gallon Sewage Spill in Hawaii: Reliability of Culture Assay for FRNA Coliphages and PCR Assay for Bacteroides Roger Fujioka, Ph.D. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)118 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Heavy rains caused the discharge of 48 million gallons of raw sewage into the Ala Wai Canal. This canal discharges out to sea near popular beaches. The Department of Health closed the nearby beaches (Waikiki, Magic Island, Ala Moana) based on the C. perfringens state water quality standard rather than the enterococci U.S. Environmental Protection Agency standard. This caused the public to be confused and distrustful. The University of Hawaii monitored the same beach sites for more sewage specific microorganisms (F+ coliphages by culture, human specific Bacteroides by PCR). The results showed that the beaches were contaminated with sewage two days after the sewage spill ended but had been cleared by the fourth day. These results supported the Department of Health's decision of opening the beaches six days after the end of the sewage spill. The heavy rains that caused the sewage spill also diluted and transported the sewage out of the canal and out to sea.

Select this Article		Effective Rainwater Harvesting Schemes for Sub‐Saharan West Africa Emmanuel U. Nzewi, M. ASCE and Stephanie Luster‐Teasley ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)119 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract According to United Nations (UN) data, over one billion people lack access to domestic water supply and 2.4 billion people lack elementary sanitation. The World Health Organization (WHO) estimates that by the year 2020, the number of people without access to water services will increase from 300 million (in 2003) to 400 million. In addition, by 2030, more than 50% of the population on the African continent will live in urban areas thereby increasing the demand on already stressed water resources. This paper describes how rainfall harvesting could be implemented to improve the availability of water in certain parts of West Africa. The implementation of rainfall harvesting strategies could result in very effective and sustainable water supply alternatives in the regions considered. The methods described focus on the implementation of solutions particularly tailored for the region. While most rainfall harvesting schemes focus on domestic rainfall harvesting (DRH) and thus water supply alternatives for residential use, this paper additionally explores water supply alternatives that could serve small communities like schools and small business centers. A brief discussion of Living Machines (LMs) is provided to motivate the presentation of larger‐scale integrated rainfall harvesting and water recycling methods. The function and the basic principles underlying the development of LMs are included. The goal is to examine adaptations of LMs in the development of larger scale water systems that include rainfall harvesting and water recycling.

Select this Article		Variations in High‐Intensity Precipitation under Climate Changes in the LMRB and Implications for Drinking Water Supply Security Y. Jeffrey Yang, Ph.D., P.E., Roy C. Haught, Jill Neal, Katherine Carlton‐Perkins, Timothy C. Keener, Ph.D., P.E., and Joo‐Youp Lee, Ph.D. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)120 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A systematic temporal and spatial analysis is being conducted at the U.S. EPA on historical precipitation and stream flow in the Lower Mississippi River basin (LMRB) and their relationships with Atlantic hurricanes and flooding events. The objectives are to decipher the periodicity and long‐term trends exhibited in the hydroclimatic regime, and to determine their implications on the security of community water supplies in the region and the Gulf Coast, the parts of the continental U.S. prone to the negative impacts of extreme weather events under the current and future climate conditions. Statistical modeling using wavelet functions shows periodicity of continental precipitation and hurricanes with characteristic changes of trends around 1890–1900, 1940–1960, and the 1990s. These long‐term decadal and multi‐decadal changes were identified in a spatial modeling and wavelet frequency analysis of the 24‐hour daily precipitation data obtained from the National Climatic Data Center. Long‐term variations are also detected in hurricane and flooding events. Based on these findings, one can incorporate the hydroclimatic periodicity and long‐term variations into the emergency water supply management and system designs. Measures such as water intake protection, using decentralized water supply, and planning emergency management are potential options in natural disaster preparedness. The results of the first phase investigation are discussed.

back to top

EMERGING TECHNOLOGIES FOR WATER AND WASTEWATER TREATMENT

Select this Article		Catalyzed Hydrogen Peroxide as an Alternative Disinfection Technology for Wet a Weather Sewer Overflows E. Coyle, P.E. and L. Ormsbee, P.E., Ph.D., M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)121 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Traditional technologies exist to address wet weather overflows but are many times cost prohibitive, can yield toxic by‐products and in areas of older infrastructure, space for facilities to treat overflows is often limited if available at all. As such more cost effective technologies, requiring less space and producing less harmful by‐products are currently being explored. One such possibility for alternative high‐rate disinfection has been investigated using hydrogen peroxide in conjunction with a catalyst to speed up the oxidative reaction. Given that the only by‐products of the reaction with hydrogen peroxide are water and oxygen, a reaction with a short contact time and high kill rate can prove not only valuable where space is limited, but is also extremely environmentally sound.

Select this Article		Impact of Nanoparticles on the Removal of Organic Pollutants by Activated Carbon Adsorption Anthony Jasper, George Sorial, Ph.D., Rajib Sinha, P.E., Radha Krishnan, P.E., and Craig. L. Patterson, P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)122 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The presence of nanoparticles in drinking water sources could impact organic pollutant removal by activated carbon due to agglomerated nanoparticles, which could act as adsorption sites for pollutants. Trichloroethylene (TCE) adsorption onto activated carbon in the presence of nanoparticles was evaluated in this study. Iron oxide (Fe₂O₃), titanium dioxide (TiO₂), and silicon dioxide (SiO₂) nanoparticles at two concentration levels (0.5 and 1.0 mg/L for Fe₂O₃ and TiO₂, and 5.0 and 10 mg/L for SiO₂) were evaluated. Particle size distribution (PSD) of the above nanoparticle solutions was analyzed in order to determine the extent of aggregation. Adsorption isotherm experiments were conducted at three initial TCE concentrations, two nanoparticle concentrations, and with varying amounts of powdered activated carbon (PAC). Isotherm experiments were also conducted in the presence of natural organic matter (NOM) in order to more closely model natural water conditions. The primary objective of this study is to evaluate the efficacy of activated carbon adsorption of TCE in the presence of the aforementioned commercially available nanomaterials and NOM.

Select this Article		The Impact of State Regulations on Innovative Wastewater Treatment Implementation: Trends for On‐Site Wastewater Disposal in North Carolina Peter Rojeski, Jr., Ph.D., P.E. and Stephanie Luster‐Teasley, Ph.D. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)123 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract In many suburban areas in the United States, innovative onsite wastewater treatment technologies are often the most cost‐effective solution when poor soil conditions exist. In many situations, the use of aerobic treatment units with drip or spray effluent dispersement is the most cost effective onsite wastewater treatment solution. Although the science and engineering of this system concept is well‐established, the interpretation of this science, as embodied in state and local codes, varies significantly. The consequences of these variations in code result in suburban areas where development is flourishing while in other suburban areas development is limited. This paper compares state onsite waste water code regulations for North Carolina, Texas, Virginia, Tennessee, and Pennsylvania.

back to top

EVOLUTIONARY COMPUTATION I

Select this Article		Application of Artificial Neural Network Models for Flow Estimation In a Large Constructed Wetlands — Stormwater Treatment Area 2 in South Florida Chandra S. Pathak and Jie Zeng ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)124 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The South Florida Water Management District (District) is responsible for managing water resources in 16‐counties over a 46,439‐square kilometer (17,930 square‐mile) area. The District's area extends from Orlando to Key West and from the Gulf of Mexico to the Atlantic Ocean and contains the country's second largest freshwater lake, Lake Okeechobee, and the world‐famous Everglades wetlands. The District manages water in one of the most diverse and complex ecosystems in the world — the interconnected Kissimmee‐Okeechobee‐Everglades system. The District's routine work includes buying and managing land, restoring floodplains, revitalizing shoreline habitats, and protecting wetlands. The District's mission is to provide regional flood control, water supply, and water quality protection as well as ecosystem restoration. During last ten years, the District has constructed and operates six Stormwater Treatment Areas that are large constructed wetlands to reduce the nutrients in water. Specially, six Stormwater Treatment Areas are designed to reduce the level of phosphorus entering the Everglades. Stormwater Treatment Area 2 (STA‐2) is located in southern Palm Beach County and captures stormwater runoff originating from the S‐6 watershed, upstream of the S‐6 pump station. The STA is populated with sawgrass and cattail to reduce phosphorus levels, before it is released into Water Conservation Area 2A. STA‐2 has many water control structures including pumps and gated culverts and spillways. These water control structures have complex hydraulic conditions that require a set of complex physics‐based flow estimating equations. The Artificial Neural Network (ANN) models were developed, tested and validated for flow estimation purpose at the water control structures. Their application in estimating flow and missing tail water elevations at water control structures culverts G331 and G333, and spillway G332 were successfully demonstrated in a case study.

Select this Article		Designing BMPs at a Watershed‐Scale Using SWAT and a Genetic Algorithm P. Kaini, K. Artita, and J. W. Nicklow ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)125 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract An optimal control model (OCM) is developed by coupling a semi‐distributed hydrological model, Soil and Water Assessment Tool (SWAT), with a genetic algorithm (GA) to identify the least cost design (sizes, types, and locations) of structural best management practices (BMPs) while meeting treatment goals at a watershed‐scale. Treatment goals considered are constraints on daily peak flow values and annual sediment load. SWAT performs the hydrological simulation incorporating combinations of BMPs while the GA searches for the least cost combination. Structural BMPs included in the OCM include detention ponds, infiltration ponds, parallel terraces, filter strips, grade stabilization structures, and grassed waterways. The model is demonstrated on Silver Creek watershed, a sub‐watershed of the Lower Kaskaskia basin in Illinois. The OCM is able to find optimal or near optimal solutions for different scenarios of treatment goals.

Select this Article		Evaluation of the Performance and Parameter Sensitivity of Constraint‐Handling Techniques for a Genetic Algorithm‐Based Watershed Management Problem Laura J. Harrell, A. M. ASCE and Kwisun Park Yu ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)126 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Handling constraints in Evolutionary Algorithms (EAs) can be a challenging issue. Because constraints are not handled directly, heuristics must be carefully designed and applied to guide the search toward feasible and good‐performing solutions. Penalty functions are the most commonly used method to handle constraints in EAs. There are many possible formulations for penalty functions. One drawback of penalty functions is that they require time‐consuming fine‐tuning of the penalty parameters to effectively search for feasible solutions with good objective function values. Alternative techniques have also been reported in the literature, including multi‐objective optimization techniques, which treat the constraints in single objective problems as additional objectives. In this paper, various constraint‐handling techniques are applied to an EA‐based watershed management problem to investigate their performance and sensitivity to fine‐tuning parameters. The watershed management problem involves designing detention ponds in a system‐wide manner in conjunction with land use allocation to provide a desired level of long‐term system‐wide pollutant removal at the least cost. The constraint‐handling methods investigated include several penalty functions and alternative constraint‐handling techniques. The associated fine‐tuning parameters for each constraint‐handling method are varied to investigate the sensitivity of the solution quality (feasibility and objective function value) to these parameters. The solution quality and its sensitivity to the constraint‐handling parameters are compared. This comparison is intended to help provide guidelines for better‐performing constraint‐handling methods for a watershed management problem that can be successfully implemented without excessive fine‐tuning requirements.

Select this Article		Generating Alternative Watershed‐Scale BMP Designs with Evolutionary Algorithms K. S. Artita, P. Kaini, and J. W. Nicklow ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)127 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The first part of a two‐step decision‐making framework for watershed‐scale stormwater runoff control (Kaini et al., 2008, this meeting) involves identification of the most cost‐effective combination of structural BMPs that meet target peak flow and sediment reduction criteria. This paper presents the second half of that framework: simultaneous generation of near‐optimal alternative design strategies using a Euclidean distance metric. Structural BMPs included in this model include detention ponds, infiltration ponds, field borders, grade stabilization structures, and grassed waterways. Alternative designs are identified by coupling Soil and Water Assessment Tool (SWAT) and a Species Conserving Genetic Algorithm (SCGA). In addition, we demonstrate SCGA's flexibility and efficiency at generating alternative designs as well as varying numbers of alternatives. The model is demonstrated on Silver Creek watershed, a sub‐watershed of the larger Lower Kaskaskia watershed in southern Illinois.

Select this Article		Improving Accuracy of IDF Curves Using Long‐ and Short‐Duration Separation and Multi‐Objective Genetic Algorithm Taesoon Kim, Ph.D., Ju‐Young Shin, Kewtae Kim, and Jun‐Haeng Heo ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)128 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Multi‐objective genetic algorithm (MOGA) and cumulative distribution function (CDF) are used to improve the accuracy of IDF curve. Rainfall durations are divided into short‐ and long‐duration using root mean squared error (RMSE) and relative root mean squared error (RRMSE) between rainfall quantiles by IDF curve and at‐site frequency analysis. RMSE could be used for estimating parameters of relatively long‐duration, and RRMSE for short‐duration. The compromised solutions could be ahieved through MOGA with two multi‐objective functions. The duration separating technique called C0MBI_1 is suggested and the comparison with the five different parameter estimation methods provides COMBI_1 is superior to the other methods.

back to top

EVOLUTIONARY COMPUTATION II

Select this Article		Application of Nash Bargaining Theory in Water Allocation: A Conflict Resolution Approach Mohammad Karamouz, F. ASCE, Azadeh Ahmadi, and Ali Moridi ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)129 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Operation of reservoir systems using a Bayesian Stochastic GA‐based optimization model (BSGA) is investigated in this paper. This model considers the joint probability distribution of observed inflow and forecasted inflow to the reservoir. This way, the intrinsic and forecast uncertainties of inflow are considered. In this study, a multi objective approach that considers the interest of different agencies, water users and stakeholders in water allocation from the reservoir is developed. The proposed model maximizes an objective function based on the expected value of the Nash product. The Nash objective function includes utility functions of different stakeholders/water users as well as their relative authorities on the water allocation process. This work uses the general framework of Bayesian Stochastic Dynamic Programming (BSDP) proposed by Karamouz and Vasiliadis (1992). They utilized the Bayesian decision theory in the optimization algorithm for reservoir operation. In order to test the proposed methodology, the model is applied to the Satarkhan Reservoir system in the north‐western part of Iran. The results show the significant value of the proposed model in water allocation from the reservoir considering the forecast uncertainty.

Select this Article		Hydraulic Modeling and System Optimization of the Marco Island Wastewater Collection System Expansion Jinsheng Huo, Alfred J. Mitt, Rony Joel, and Barton Bradshaw ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)130 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract This paper presents a hydraulic modeling method to optimize a cost‐effective design to expand the Marco Island wastewater collection system. Currently, approximately 60 percent of the city is served by individual septic tanks (decentralized system) and the remaining 40 percent is served by the existing centralized wastewater system. Marco Island has started the septic tank replacement program, which includes 14 sewer districts to be completed in 7 phases from year 2006 to 2012. One of the biggest design challenges is how to calibrate the hydraulic model of the existing wastewater collection system. The accuracy of simulation results is so critical because it is one of the most important factors on which key design decisions are based. Pressure gauges are used to continuously record pressure data at several lift station discharge lines. The recorded pressure data are then analyzed and compared with the simulated data to calibrate the modeling parameters and improve the model's accuracy and reliability. This will help design engineers better understand the existing collection system, and improve the future system development. Comparing actual field pressure data with the all pumps running at build‐out model scenario (“worst case”) suggests that the force main sizing and pump selections should not always be based on the worst case, which may prove to be too conservative. This less conservative approach may be more appropriate when it is not practical to upgrade pumps or force mains. Another design challenge is how to cost‐effectively expand the existing wastewater collection system in phases in coordination with the existing facilities. The goal is to maximize the utilization of the existing gravity lines, lift stations, and force mains. The construction sequence of these sewer districts is mainly determined based on the configuration of the existing transmission system and hydraulic modeling of proposed developments. Other factors are also considered including sewer districts' own features (size, location, population, etc.), and the schedule for other proposed construction projects. The hydraulic modeling proves to be a cost‐effective method to optimize the Marco Island wastewater collection system. More importantly, this method can wisely manage budgets and allocate money to projects with higher priorities based on recommendations from hydraulic simulations.

Select this Article		Multi‐Objective VLGA Model for Flood Control and Water Supply Management in a Cascade System of Reservoirs Bahram Malekmohammadi, Banafsheh Zahraie, and Reza Kerachian ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)131 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Developing a tradeoff between long‐term objectives of reservoir operation such as water supply and short‐term objectives like flood control and power generation is one of the challenging issues in reservoir operation management. In most of the monthly reservoir operation optimization models, flood control objective is only considered as a constraint for flood control storage and the probable flood damages are not usually taken into account. This can be a more important issue in cascade reservoirs, which provide more flexibility in achieving the long and short‐term objectives. In this paper, a new approach for incorporating both flood control and water supply objectives in a monthly reservoir operation optimization model is presented. The optimization model is developed using Varying Chromosome Length Genetic Algorithm (VLGA). K‐Nearest Neighbor (K‐NN) is also used as a method for selecting the initial solutions considering similarities between reservoir inflows and storages in different water years. To incorporate the expected value of the flood damage in each month, peak flow frequency analysis has been carried out and the flood damages associated with each flood have been estimated by linking a hydraulic flood routing model with GIS tools for considering the land‐use information in the flood plain. Damages due to deficit in supplying agricultural water demands are also calculated based on the functions of crop yield responses to deficit irrigation. The multi‐objective optimization model is formulated to minimize the expected flood and agricultural water deficit losses, maximize reliability and resiliency, and minimize total deficit and surplus in supplying water demands. The developed model is applied to the cascade system of the Dez and Bakhtiari Reservoirs in southwest of Iran. The results of multi‐objective model demonstrate efficiency of the model in finding pareto optimal solutions with more reliability and resiliency and less economic losses when compared with the single objective VLGA model.

Select this Article		Optimal Placement of River Monitoring Stations Huei‐Tau Ouyang, Jihn‐Sung Lai, Hsin Yu, and Chin‐Huang Lu ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)132 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A methodology by means of Geographic Information System (GIS) and Genetic Algorithms (GAs) for optimizing the spatial distribution of river monitoring stations for the detection of pollutant source in a river system is described. Two practical case studies are investigated to demonstrate the use of the method in (1) a regulatory monitoring plan for the Lanyang River System in northeastern Taiwan; and (2) a restrictive monitoring plan where the possible sampling sites are restricted to the existing flow gauge stations on the Lanyang River System. Plausible results were obtained encouraging the possibility of using GAs in river monitoring plan designs.

Select this Article		Stochastic VLGA Model for Operation Optimization of Cascade Reservoirs Banafsheh Zahraie, Caro Lucas, and Fariborz Nematizadeh ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)133 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract In this study, a Stochastic Varying Chromosome Length Genetic Algorithm model is developed in which reservoir inflow uncertaities have been taken into account. In this model, the basic concept of the Varying Chromosome Length Genetic Algorithm model (VLGA) has been used to develop a multi‐objective stochastic GA model for reservoir operation optimization. The Fast Elitist Non‐Dominated Sorting Genetic Algorithm (NSGA‐II) has also been utilized in development of the optimization model in order to be able to consider multiple objectives. The search and selection methods for the initial solutions are developed to increase the convergence speed of the model in order to be able to apply this model to multi‐reservoir systems. The developed model is applied to the cascade system of reservoirs on Karoon River in Southwest of Iran.

back to top

POINT‐OF‐USE/POINT‐OF‐ENTRY TREATMENT TECHNOLOGIES

Select this Article		Assessment of a Point‐of‐Use Ultrafiltration System for Turbidity and Microbial Pathogen Removal Craig L. Patterson, P.E., Aisha Tzillah, Nur Muhammad, Ph.D., P.E., and Jack Duffie ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)134 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract U.S. EPA's Office of Research and Development has been evaluating the performance of point‐of‐use (POU) devices designed for use in homes and small businesses for many years. In collaboration with the University of Cincinnati, a series of pilot‐scale tests were conducted on a Matrix Membranes ultrafiltration (MMUF) system at the U.S. EPA Test and Evaluation Facility in Cincinnati, Ohio. The MMUF system operates at a low flow rate (< 2 gpm) and feed pressure (< 30 psi). The polyethersulfone (PES) membrane (2″ × 21″) is designed for high flux rates with inside‐out operation. Membrane integrity tests require the injection of compressed air (10 psi) into the closed system to check for breakthrough or air bubbles in the membrane. The MMUF system requires back‐flushing when the filtrate flow drops 25%. The chlorine resistant membrane consists of 500 hollow fibers with 0.8 mm inner diameter and 1.50 mm outer diameter and contains 5.67 square feet of filter surface area. The membrane is cleaned with chlorine (2–200 mg/L) at pH 11 using sodium hydroxide. The membrane has an average pore size of 0.2 μm and a Molecular Weight Cut‐off of 100,000. The research study evaluated removal of turbidity (2, 5, and 10 ntu) and microbial surrogates (3 micron polystyrene latex (PSL) beads, MS‐2 bacteriophage, and E. coli). Other parameters of interest included system flux, runtime, raw water characteristics, and operating cost. Results are summarized and presented on turbidity and microbial removal efficiency.

Select this Article		Development of a Water Security Filtration System for Whole House Water Supply Nur Muhammad, Ph.D., P.E., Rajib Sinha, P.E., E. Radha Krishnan, P.E., Craig L. Patterson, P.E., Roy C. Haught, Harold H. Harms, and Rick Seville ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)135 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The waterborne disease outbreaks have been a constant reminder of the critical importance of ensuring safe drinking water. Properly designed and operated public water systems, either large or small, are required to protect public health. This paper presents the results of tests conducted on a multi‐layer cartridge based small system that combines physical filtration with chemical adsorption and ultraviolet light disinfection. The system was challenged with test water containing different levels of turbidity, a number of biological contaminants including B. subtilis, E. coli, MS2 bacteriophage and Polystyrene Latex (PSL) beads (as a surrogate for Cryptosporidium) and a number of chemical contaminants including methyl tert‐butyl ether (MTBE), high chlorine concentrations, drinking water treatment disinfection byproducts (DBPs) including trihalomethanes and haloacetic acids, arsenic and diazinon. This paper benchmarks the baseline performance of the system in removing physical, biological and chemical contaminants and identifies the areas for further development. The applicability of the system as a home water security device was evaluated.

Select this Article		Evaluation of Point of Use (POU) Systems for the Removal of Microbiological Contaminants in Drinking Water Rajib Sinha, P.E., Nur Muhammad, Ph.D., P.E., E. Radha Krishnan, P.E., Haishan Piao, Ph.D., P.E., Craig L. Patterson, P.E., and Joseph Cotruvo, Ph.D. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)136 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract As a final barrier before consumption, properly designed and operated Point‐of‐Use (POU) treatment systems are important for safe drinking water supplies. POU treatment devices have gained importance for protection against intentional or accidental contamination of drinking water supplies. The events of September 11, 2001 have further emphasized the importance of POU devices in this regard. This paper summarizes the results of pilot‐scale studies that were conducted at the U.S. Environmental Protection Agency's (EPA's) Test and Evaluation (T&E) Facility in Cincinnati, Ohio, to evaluate the performance of three different POU systems for removing microbiological contaminants in drinking water. Two of these systems were based on filtration through electrostatically charged media and the third system incorporated a reverse osmosis (RO) membrane. The systems were challenged with a number of microbiological contaminants including Cryptosporidium, E. coli, MS2 bacteriophage, B. subtilis and polystyrene latex (PSL) beads (as a surrogate for Cryptosporidium). The results demonstrated that these POU systems were effective in removing the target biological contaminants in accordance with the standards presented in the U.S. EPA “Guide Standard and Protocol for Testing Microbiological Water Purifiers”.

Select this Article		The Reduction of Microbial and Chemical Contaminants with Selected POU/POE Systems Jeffrey Q. Adams, Michael Blumenstein, and Bruce Bartley ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)137 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Centralized drinking water treatment and distribution alone may not always be the most practical or cost‐effective option. Also, some consumers seeking a proactive measure to reduce exposure to pathogens and chemicals not currently monitored or regulated might consider employing a POU/POE system. In addition, mobile POE and POU systems may have a proactive or reactive role in providing short‐term treatment during natural disasters and protecting high asset facilities. Four POU and two POE technologies employing combinations of RO, carbon adsorption, and other components were tested to evaluate capabilities for reducing microbial and chemical challenges under varying operating conditions. Microbial challenges included the bacteria B. diminuta and H. psuedoflava, and the coliphage viruses fr, MS2, and Phi X 174. A number of organic and inorganic chemical challenges were also conducted. The POU/POE devices evaluated in these studies showed varying capabilities for the removal of contaminants in water. Some devices showed significant contaminant reductions, but even the best performing technologies had some units from different production lots that showed microbial challenge organisms in their effluents. The POU RO components alone are not absolute microbial and chemical barriers. Despite shortcomings, POU/POE systems may be beneficial in a number of applications for individual consumers and as a managed strategy for some water utilities or emergency planners/responders.

back to top

WATER RESOURCES 2050: RETROSPECTIVE LOOK TOWARD THE FUTURE/EMERGING APPLICATIONS

Select this Article		A Simulation Tool for Assessing Sensor Performance in a Water Utility Contaminant Warning System Wayne Einfeld, Sean A. McKenna, and Mark P. Wilson ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)138 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A set of software tools has been developed to enable performance testing of candidate on‐line sensors in a utility‐specific contaminant warning system design using simulation methods. Specific sensor performance characteristics such as noise, drift, detection level, and sampling rate can be input into the simulator and contamination scenarios can be run with a contaminant transport model such as EPANET using utility‐specific pipe layouts. The sensor simulator is coupled with event detection software and together the two modules can provide an indication of how well the sensor will perform in a specific utility setting with user‐defined contamination events. Water quality baseline data from utility measurements using on‐line sensors are also incorporated into the analysis for a more realistic simulation. The software enables a determination of the rate of true positive, false positive, true negative, and false negative events during the simulation. Results from this analysis reveal that on‐line residual chlorine and total organic carbon sensors combined with several different event detection algorithms can provide reliable detection for a variety of chemical contamination events. Study results further indicate this simulation tool concept is useful for pre‐installation evaluation of contaminant warning system design in a specific utility setting.

Select this Article		Developing Virtual Drought Exercise Scenarios: A Case Study Mohammad Karamouz, F. ASCE, Saleh Ahmadinia, and Sara Nazif ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)139 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract There is an increasing need for developing strategies to face droughts because of high dependencies of societies on water. This need has been intensified due to the water scarcity and the impact of climate change. The frequency and magnitude of droughts have been increased in many parts of the world because of climate change effects. When facing droughts, using sound strategies in real time could decrease the drought damages considerably. Virtual Drought Exercise (VDE), a strategy for drought management, can increase a system's readiness to deal with droughts. VDE gives the decision makers the opportunity to simulate the disasters without taking any risk. In this study, an algorithm for VDE has been presented. In developing VDE scenarios, the first step is identification of key triggers of drought. In this paper, after determination of all effective triggers on drought management, their consequences are evaluated using the unranked pairwise comparison technique. The triggers with greatest impact can be used for developing VDE scenarios. The Ahar‐chay river basin located in northwestern Iran has been as case study of this paper. Utilizing the proposed scenarios, decision makers can prepare the system for better management of water shortages during droughts.

Select this Article		Water Resources and Environmental Issues in 2050: A Retrospective Look Toward the Future Walter M. Grayman ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)140 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The past 40 years have witnessed many changes in the fields of water resources and environmental engineering. In some respects, the tools and methods used to analyze and design water systems have undergone significant changes. However, in other respects, there has been a gradual evolution but the underlying concepts and methodologies have changed very little. This paper is part of session that will first look back at how water resources and environmental planning has changed over the past 40 years and then attempt to look over the horizon at what water resources and environmental engineering will look like 40 years from now by exploring the insights of a select group of leading engineers and scientists. Topics may include how the politics of global warming or the advent of new technologies such as nanotechnologies influence water resource and environmental engineering policy and practice. A panel of experts will discuss these future changes and attempt to answer the fundamental question of what we must do to prepare ourselves and those for whom we have responsibility to face future environmental and water resource challenges. This is the initial event in a series of future activities planned by the Emerging and Innovative Technology Committee to look at 2050 visioning in the water resources and environmental area.

back to top

INTERNATIONAL WATER HISTORY

Select this Article		C. Y. O'Connor and His Goldfields Water Supply Scheme David R. Gilbert, P.E., F. ASCE, M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)141 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract As a young mining engineer early in my career I was attracted to Western Australia in the late 1960's when the iron ore mining business was in the midst of a tremendous boom. I met a young lady there who would later become my wife and so established a close and permanent tie with this interesting but remote region of Australia.

Select this Article		From Colosseum to Cathedral: Building Big in the European Dark Ages Augustine J. Fredrich, P.E., F. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)142 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Relatively speaking, much is known about the construction prowess of Roman engineers. The existence of structures such as amphitheaters like the Colosseum in Rome, temples like the Pantheon, aqueducts like Pont du Gard, structures like Hadrian's Wall, and the remnants of the network of Roman roads that crisscrossed the Empire give mute testimony to both how big and how well they could build. Similarly, the great churches of Florence, Chartres, Lincoln, Cologne and dozens of others give witness to the abilities of the cathedral builders of the Middle Ages. Although there are great gaps in our knowledge of the identities of the builders and their methods, what we know is encyclopedic compared to our knowledge of construction activities during Europe's “Dark Ages”—the seven centuries between the fall of the Roman Empire and the rise of the great churches. This review reveals, however, that “building big” continued through those years.

Select this Article		Gateway to Greatness — A Profile of James B. Eads J. L. Weiland and M. T. Buechter ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)143 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract James Buchanan Eads (1820–1887) is today recognized as one of America's greatest citizens, and in 1932, the Deans of American Colleges of Engineering named him as one of the five greatest engineers of all time, placing him in the company of Thomas Edison and Leonardo Da Vinci. He is perhaps best known for his role in constructing the St. Louis Bridge, now called the Eads Bridge, across the Mississippi River in St. Louis, Missouri. This bridge was completed in 1874, and at the time it was the longest span bridge in history and was the first of its kind to employ a steel arch design. As a testament to Eads' engineering expertise, the bridge is still in use today by St. Louis's Metro light rail system and by highway traffic. It was, and still is, considered a great accomplishment of engineering and aesthetics. Though Eads was never formally educated as a civil engineer, his years of experience as a river salvage captain helped him amass his vast knowledge of the workings of the Mississippi River, and provided him with the wealth and influence necessary to launch future business ventures, including building the St. Louis Bridge. The accomplishments of James Eads also included design and construction of steam‐powered ironclad warships during the Civil War; these ships were pivotal in the defeat of the Confederacy. In all, Eads intimate knowledge of the River allowed him to make several long lasting contributions to both his country and his profession.

Select this Article		Middle Eastern Hydrologic History and Water Developments Mohammad Karamouz, F. ASCE and Sara Nazif ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)144 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract In this paper, the history of water development activities related to Persian, Egyptian and other civilizations in the Middle East are discussed. The historical developments of Qanats, Madies, small dams as well as drainage systems, some still functioning, are addressed. An overview of Nile River with it's over 1000 years of hydrological data, is presented. This river has been the centerfold of many water development activities that have affected the life of many people and the social and political developments in the north‐east Africa. This discussion is followed by an overview of different stages of Aswan dam construction and operation. Finally, construction of many large dams as well as irrigation networks and desalination plants and water development in the last 30 years in the Middle East are discussed.

Select this Article		The Hydraulics of Roman Aqueducts: What Do We Know? Why Should We Learn? Hubert Chanson ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)145 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The Roman engineers were at the forefront of science and their engineering heritage included some magnificent aqueducts, many of which are still standing. While some scholars suggested that Roman engineers did not know the basic principle of conservation of mass, the Roman aqueducts provide a clear demonstration of the high level of hydraulic engineering expertise. The successful design and operation of these outstanding systems were massive achievements by modern standards. The development of regulation basins, culverts and energy dissipators was far from obvious. It is the writer's opinion that the leading Roman hydraulic engineers involved with the major aqueducts in Gaul and North‐Africa understood the concepts of continuity and momentum.

back to top

SELECTED HAWAII/INTERNATIONAL DAMS AND U.S. REGIONAL WATER HISTORY

Select this Article		California's Water Resources History and The Central Valley Project's First 75 Years Richard L. Wiltshire, P.E., F. ASCE and James L. Martin, P.E., Hon. M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)146 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Over the last 150‐plus years, California has been a leader in the development of water resources and infrastructure, which have more recently involved transferring scarce water from available sources to needy destinations. The 1930s Central Valley Project involved large dams, lengthy canals, pumping stations, and other important features. It helped turn the Central Valley into one of the most productive agricultural areas in the world. This paper traces the important history of California's water resources and infrastructure development; highlights the CVP's origin, planning, design, construction, operation, and recent developments; and focuses on some of the people who made major contributions.

Select this Article		History of Some Significant Dams in Hawaii Peter G. Nicholson, Ph.D., P.E., F. ASCE and C. S. Papacostas, Ph.D., M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)147 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Until the catastrophic dam failure on Kauai during the spring of 2006, many, if not most people didn't realize that Hawaii had any significant dams. In fact, there are over 130 dams in the inventory that are large enough to be under the State's jurisdiction. Over half of these dams are classified as “high hazard” dams with the potential to cause loss of life and property should a failure occur. This number may in fact be low. At the time of failure, the Ka Loko Dam was classified as a low hazard dam but subsequently killed seven people and swept away a number of homes. Many of the dams in Hawaii were constructed around the turn of the century (1900) or in the few decades following to supply water for irrigation to support the sugar industry. The consequence of this is that not only are most of the dams old and aging, but many were not constructed with a high level of engineering. Furthermore, the natural soil and foundation materials in Hawaii are typically poor with respect to quality dam construction. Review of a number of dams in Hawaii shows a history of problems, a number of failures and other “incidents” which have surfaced in recent years. These will be described along with how the State is coping with its aging dam inventory.

Select this Article		Inundation, District Creation, and Urbanization: The History of Flood Control in Harris County, Texas K. N. White, P.E., S. D. Fitzgerald, P.E., and J. Rogers, Ph.D., P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)148 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Harris County, home to the City of Houston, is no rookie to flooding and flood control tactics. While the population in 1836 was less than 2,000 citizens, it is now the third most populous county in the United States facing new development and new flood control needs on a regular basis. Downtown Houston experienced devastating floods in 1929 and 1935 which led to the development of the Harris County Flood Control District (HCFCD) in 1937. Over the past 70 years, the HCFCD has taken on the challenging task of keeping the flood control tools, policies and systems up to date with the rapid urbanization of the County. This paper will review a timeline of the County's growth and flooding alongside the past 70 years of community accomplishments.

back to top

WATER AND ENVIRONMENTAL EDUCATION I

Select this Article		Challenges and Opportunities of Interdisciplinary Programs: A Water Resources Management Perspective Charalambos Papelis ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)149 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Problems in science and technology are frequently complex and require the collaborative efforts of large teams with a wide range of expertise. It is, therefore, not surprising that interdisciplinary programs continue to be attractive across campuses in the U.S. The benefits from such programs are numerous. First, faculty from different departments, and even colleges, can participate in multiple interdisciplinary programs. In addition, interdisciplinary programs frequently allow admission of students with varied backgrounds, compared to traditional departments that may have stricter background requirements. The variety of faculty and student backgrounds contributes greatly to a unique and stimulating experience. Unfortunately, however, interdisciplinary programs may face significant challenges in the traditional university structure. These challenges are often traced to lack of resources and lack of faculty and curriculum control. Management of scarce water resources in the arid U.S. Southwest is particularly suitable to an interdisciplinary approach, because in addition to hydrologic engineering and sciences, political and socioeconomic aspects must also be considered. This paper explores some of these challenges and opportunities and offers suggestions to maximize the positive and minimize the negative aspects of interdisciplinary programs.

Select this Article		The Continuing Challenges of Running Successful Interdisciplinary Graduate Programs John J. Warwick, Ph.D., P.E., M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)150 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Interdisciplinary Graduate Programs (IDGPs) have grown in number and notoriety throughout the past 20 years, yet fundamental challenges regarding resource allocation and control remain mainly unresolved. The author herein presents his own admittedly biased views regarding the major challenges to running successful IDGPs and what steps might be taken to address these challenges. The identified challenges include the control of resources (personnel and funding), communications, disaggregated space, and fundraising.

back to top

WATER AND ENVIRONMENTAL EDUCATION II

Select this Article		Expanding the College Classroom: Developing Engineering Skills through International Service‐Learning Projects Mary McCormick, Christopher W. Swan, A. M. ASCE, Douglas Matson, David M. Gute, and John Durant, A. M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)151 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Project‐based service‐learning (PBSL) is a valuable pedagogical tool which confers educational benefits that extend far beyond the charter of traditional classrooms. This unique form of experiential education is based on a synergistic model in which community service is integrated with the academic learning objectives. In the context of providing engineering services to poor communities in developing countries, students are able to participate in all aspects of the engineering design process including problem formulation, consideration of alternative technologies, and design, construction, and evaluation of selected technologies. The reciprocal relationship that forms between the students and community nurtures personal growth and a deeper sense of social responsibility among students while empowering communities as they become more self‐sufficient. As an advocate of this pedagogy, Tufts University has provided opportunities for students to work on water infrastructure projects in Ecuador, El Salvador, Ghana, and Tibet over the past four years. Although the challenges students face are unique to each project, overcoming them allows students to develop problem solving skills that they would not otherwise get in their college education. Over the last few years, concerns have escalated among many national organizations over whether today's engineering students are being adequately prepared for future challenges; globalization, sustainability, complexity, and adaptability. To address this situation, the National Academy of Engineering (NAE), the Accreditation Board for Engineering and Technology (ABET) and the American Society of Civil Engineers (ASCE) have all generated reports aimed at reforming the existing engineering curriculum. As a result, the NAE's Engineer of 2020, ABET's Engineering Criterion 3 (EC 2000), and ASCE's Body of Knowledge (BOK) all aim at shifting the existing paradigm of engineering curriculum towards a more well‐rounded education. The commonality among these three documents is improving students' problem solving techniques. The future will inevitably bring unanticipated crises; engineers will need to identify the problems and collaboratively formulate innovative, feasible solutions. This research hypothesizes that service‐learning can serve as a mechanism that will allow students to develop the necessary problem solving skills. To investigate this hypothesis, an education assessment instrument is employed to examine whether students who have participated in service‐learning projects have stronger analytical, practical, and creative abilities than students who have only been exposed to the conventional “classroom” education.

Select this Article		Gearing Up for Civil Engineering Review of a Summer Institute for Increasing Under‐Represented Students in Civil & Environmental Engineering Kathleen M. Leonard, F. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)152 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The numbers of female and minority students enrolled in engineering schools have been increasing slowly within that previous two decades, however there is still a relatively small percentage drawn to the field of civil engineering. As a consequence, there is a need to educate young people about the profession to encourage under‐represented individuals to appreciate the contributions of engineers and encourage them to become civil engineers. The summer institute held at the University of Alabama in Huntsville consisted of bringing middle school students, to the campus for a week of interactive science and engineering experiences. The strategy of this program was aimed at producing students who know “how to find out” and “how to examine and evaluate evidence.” The participants gained knowledge about the role of engineers in society, as well as practiced applying simple science concepts to solve design problems.

Select this Article		Life‐Long Learning in Water Resources Professional Education Rafael G. Quimpo, M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)153 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The outcomes criteria of the Accreditation Board for Engineering and Technology (ABET) mandate that new graduates with a degree in civil engineering must demonstrate a proficiency to engage in life‐long learning. Many Civil Engineering programs have redesigned their curricula to meet this objective. In teaching hydrology, there are several ways in achieving this goal. These include exposure to the details of hydrologic engineering design through field trips to completed and on‐going projects; and, through guest lectures in class by practicing hydrologic engineers. Another approach is to exploit the potential of letting undergraduates take advantage of resources that are available to them in the public data bases. This paper outlines how the tools for life‐long learning are incorporated in an upper‐level undergraduate course in hydrology. Synchronized with the sequence of topics in the traditional engineering hydrology course, the collection and analysis of geographic and hydrologic information from external sources are inter‐woven in the syllabus. The topics range from using federal web sites to explain the importance of hydrology in sustainable engineering, the delineation of watershed boundaries through extraction of GIS information from federal and state sources and the access of watershed information from web sites to download rainfall and runoff data to validate runoff prediction models. These resources continually evolve and water resources professionals will need to keep up‐to‐date after they leave the campus. In‐class experience with examples will be presented.

Select this Article		The Barrett Scholarships: Sponsoring Undergraduate Student Research in Environmental Engineering to Encourage Professional Problem Solving and Communication D. M. Rizzo, M. Paul, C. F. Farmer, P. N. Larson, J. Matt, K. M. Sentoff, I. M. Vazquez‐Spickers, and A. R. Pearce ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)154 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract University of Vermont College of Engineering and Mathematical Sciences (UVM‐CEMS) and the Barrett Foundation have established a scholarship program for undergraduate students in engineering, physical and natural sciences who wish to pursue independent research aimed at solving environmental problems. The Barrett Scholarship program was specifically designed to create a more knowledgeable and effective engineering workforce by reinforcing the technical (e.g., systems analyses, information technology (IT)) and “soft” skills (e.g. teamwork, communication, leadership) needed for solving environmental problems. The intent was to help retain student interest early in their engineering careers when few of their first or second year classes have any engineering or real‐world applications. Fourteen scholarships have been awarded over the three‐year pilot project covering a range of topics. During the summer research months, the Barrett Scholars meet regularly with their advisors and project affiliates. They prepare written and oral presentations to communicate their work and many of them participate in campuswide student research events. Past recipients report their experiences with the Barrett Scholarship program to be extremely valuable in their job searches, interest in graduate studies and to their work experience.

back to top

WATER AND ENVIRONMENTAL EDUCATION III

Select this Article		Assessment of Water Conservation Education Mysore Narayanan ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)155 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Leading scholars in the area of Cognitive Science and Educational Methodologies have concluded that it is essential that students need to be taught in a learning environment that enables them to acquire real‐world problem‐solving skills. The 21^st century workplace does not need employees who have just mastered a particular body of information, instead it prefers to have liberally educated workforce who have mastered written and oral communication skills in addition to acquiring knowledge in their chosen discipline. Educators should not allow the students to wonder whether they have been learning anything that would actually serve them in the workplace, upon graduation. It is also important to recognize that state legislatures have introduced and are in the processes of introducing demands for outcome assessment. In this paper the author outlines how assessment techniques he has generated, can help an instructor in promoting a learning environment. Furthermore, he also provides initial results of his findings pertaining to assessment data he has collected.

Select this Article		High School Engineering Courses in Colorado Cassie C. Klumpp ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)156 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Project Lead the Way (PLTW) is a highly successful K‐12 pre‐engineering program taught in high schools across the country. The High School Program is a four year sequence of courses which, when combined with traditional mathematics and science courses in high school, introduces students to the scope, rigor and discipline of engineering prior to entering college. The PLTW curriculum was first introduced to 12 New York State high schools in the 1997 – 98 school year and was developed at the Rensselaer Polytechnic Institute. A year later, PLTW field tested its four unit Middle School Program in three middle schools. Today, the programs are offered in over 1,300 schools in 45 states and the District of Columbia. At least 20 high schools in Colorado have implemented the program into their curriculum. The purpose of this paper is to describe the benefits and implementation of the program in Jefferson County Schools in Colorado. The benefits and problems with the program will be identified. Students and teachers will be interviewed.

Select this Article		The University of Missouri‐Rolla's Jackling Intro to Engineering Summer Camp Andrew Curtis Elmore, Ph.D., P.E. and Ralph E. Flori, Ph.D. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)157 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The Missouri University of Science and Technology is Missouri's technological university where over 80 percent of the undergraduate student population majors engineering. Total on‐campus enrollment at S&T has been increasing in recent years, and now tops 5,500 students. Part of the successful recruiting effort is S&T's comprehensive collection of summer precollege programs. The largest and oldest precollege program is called Jackling Introduction to Engineering. This highly successful program which is more than 30 years old hosts over four hundred high school students annually over three summer camp sessions. This week‐long camp, geared to high school rising juniors and seniors, helps students discover the excitement of engineering and to identify the kind of engineering that is best for them. They learn about the engineering profession and solve some simple engineering problems. They learn about the different engineering majors offered at S&T, they tour some of the engineering and science programs, and they participate in afternoon hands‐on activities in the programs that they select. They live in residence halls for five nights, walk daily on campus, attend classes and work in labs. They have ample contact with faculty, graduate students, and undergraduates. Geological engineering and environmental engineering faculty have offered field trips of environmental interest, and these activities are representative of activities which other academic programs offer.

back to top

AIR QUALITY ISSUES

Select this Article		Air Quality Monitoring and Assessment of PM₁₀, SO₂ and NO_x in Beijing by an Industrial Source Complex Model with GIS Gaoxiang Ying, Jia Ma, and Yongqi Lu ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)158 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract As an integrated part of management plan against the elevated air pollution, typical monitored emission inventory was presented for metropolitan area of Beijing in 1999. The air pollutants of concern were fine particulate matters (PM₁₀), sulfur dioxide (SO₂), and nitrogen oxides (NO_x). Emissions of these air pollutants were estimated by suitable emission factors and evaluated in three categories of point, area and line sources. Total yearly mean emissions in the studied area were estimated as 103,298 tons of PM₁₀, 209,914 tons of SO₂, 225,394 tons of NO_x. To assess the air quality, Industrial Source Complex‐Short Term (ISCST3) dispersion model was applied by combining measured emissions and meteorological data with 1 hour temporal and 1km×1km spatial resolution. Validity of model was verified by comparing the monitored data from Beijing′s Environmental Protection Bureau with the model values predicted. Demonstrated by Geographical Information System (GIS), results indicate that the levels of PM₁₀, SO₂, and NO_x were serious and endangered the regional human health. While area source accounted for 83.8% of PM₁₀ concentration distribution and 79.2% of SO₂ concentration distribution respectively, line source contributed 73.5% of NO_x concentration distribution. It reveals insight on emission control priorities and future implementations of effective control technology.

Select this Article		Intersection Air Pollution Emission Prediction Using Software Hyroad; A Case Study Fatemi‐Valiasr Intersection from Iran S. Oladnia, M. Saeedi, and A. Rezaei Bazkiaei ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)159 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Pollutant emission rates for constant speed conditions distinctly differ from inconstant speed conditions of vehicles. In intersections, vehicles are forced to reduce speed, change direction, and most likely, stop for a long period of time. Pollutant CO has the most emission changes in intersections because of dramatic speed change in intersections. In this investigation concentration of CO in one of most populated and residential intersections of Iran's capital have been modeled using software hyroad. Modeling practice has been done considering several parameters, with the extent of data available on each parameter, including; traffic flow, meteorological and weather characteristics, site specific characteristics and realistic characteristics of vehicles. Amount of CO concentration obtained from model has been compared to recorded amount of CO for specific period of data available, reliability of model to predict the actual concentration of CO in this intersection has been assessed. Results shows that predicted amounts are less than actual site amounts but there is some apparent similarity associated with the change patterns of concentration, i.e. the highest and lowest concentration levels occur in the same time but with higher amounts for predicted amounts in all times.

Select this Article		MACT Update and the Often Overlooked General Provisions F. Jason Martin, P.E., M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)160 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The Clean Air Act requires the US EPA to regulate emissions of hazardous air pollutants (HAPs) under regulations know as Maximum Achievable Control Technologies (MACTs). These MACTs are embodied in National Emission Standards for Hazardous Air Pollutants (NESHAPs). MACT standards are developed for individual source categories, such as Publicly Owned Treatment Works (POTWs) and Industrial, Commercial, and Institutional Boilers and Process Heaters. EPA initially listed 174 source categories for regulation under MACT standards, and is required to evaluate the list every 8 years. The majority of the MACT standards can be found in Title 40 Code of Federal Regulations Part 63 (40 CFR 63); the MACT standard for each source category is located in a separate subpart of 40 CFR 63. In addition to the source category specific requirements found in each subpart there are General Provisions that apply to each source that is regulated by a MACT standard. These General Provisions are found in 40 CFR 63 Subpart A. Applicable MACT requirements are generally included in each facility's air quality operation permit and become an important element in facility compliance. This paper provides a brief overview of the MACT rules, a discussion of the General Provisions, and an update on two recent changes to the MACT rules.

Select this Article		Odor Control in the 21^st Century: Why 99% H₂S Removal May Not Meet Client Needs Bruce DiFrancisco, P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)161 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract This presentation discusses a comprehensive methodology for designing odor control systems for wastewater plants and lift stations. Historic design of odor control systems has revolved around a 99% removal of hydrogen sulfide (H₂S) and a typical influent concentration of 20 to 50 ppm, or a two log removal. Detection of H₂S by the human nose is at the 0.2 ppb level, with recognition of the unique H₂S odor at 0.5 ppb. An additional three log removal is required between the exhaust stack and the closest customer's nose. Oftentimes, this secondary design element is not considered. The author's approach addresses this secondary design element as part of an overall modification to the traditional odor control design. The author also stresses the need for engineers to improve communications with clients to determine client needs.

back to top

ENDOCRINE‐DISRUPTING CHEMICALS AND MICROPOLLUTANTS

Select this Article		Biotransformation of Pharmaceuticals and Personal Care Products (PPCPs) during Nitrification: The role of Ammonia Oxidizing Bacteria versus Heterotrophic Bacteria Wendell O. Khunjar, Jolanta Skotnicka‐Pitak, Nancy G. Love, Diana Aga, and Willie F. Harper, Jr. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)162 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Preliminary experiments to investigate the fate of 17α‐ethinylestradiol (EE2) during nitrification were conducted. Sorption experiments were performed by incubating inactivated ammonia oxidizing bacteria and various heterotrophic cultures in the presence of ¹⁴C‐EE2 at 10 μg/L. Biotransformation experiments utilized LC‐MS and LC‐ITMS analysis of supernatant collected during batch cultivation of monoculture of Nitrosomonas europaea with EE2. Results confirmed that sorption of EE2 onto heterotrophic biomass is an important mechanism that must be considered when describing the fate of EE2. During batch incubation with N. europaea, 98% of EE2 was transformed, producing a unique metabolite corresponding to a mass/charge ratio of — 386 m/z. Short term inhibition study results also suggest that inhibition of respiration in N. europaea as measured through nitrite generation rates is not significant at concentrations at or below 1 mg EE2/L.

Select this Article		Removal of Pharmaceuticals and Personal Care Products during Activated‐Sludge Wastewater Treatment Eric Dickenson and Jörg E. Drewes ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)163 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The recent detection of a variety of emerging organic contaminants (EOCs), such as Pharmaceuticals and personal care products (PPCPs), in municipal wastewater effluent has raised concerns about the presence of these compounds in reclaimed water and the environment. The sludge retention time (SRT) is a critical operational parameter for secondary wastewater treatment that can be potentially optimized to enhance the removal of EOCs by biodegradation. The objective of this study was to assess the effect of SRT on the biodegradation of PPCPs during activated‐sludge wastewater treatment using an experimental setup that consisted of a laboratory‐scale flow‐through activated‐sludge system. The activated sludge system was operated at SRTs of 1, 5, 10, 35, 55, and 120 days and critical SRTs were determined for the removal of 18 PPCPs.

back to top

ENVIRONMENTAL AND PUBLIC HEALTH IMPACTS OF EMERGING CONTAMINANTS

Select this Article		Drinking Water and Environmental Public Health Tracking: Assessing Statewide and Local Water Quality Data Sources Craig Wolff, Ambarish Vaidyanathan, James VanDerslice, Ph.D., and Kristen Malecki, Ph.D. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)164 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Environmental Public Health Tracking (EPHT) is the ongoing collection, integration, analysis, interpretation and dissemination of data from environmental hazard monitoring, and human exposure and health effects surveillance. The Centers for Disease Control and Prevention (CDC), in a cooperative agreement with 17 state and local health departments, is leading the initiative to build a national tracking network by drawing on expertise from federal, state and local agencies. As part of this effort, a national workgroup was formed to identify appropriate drinking water quality data and measures for inclusion in the tracking network. In order to identify current gaps in data and information, and assess the feasibility of developing measures of drinking water quality, the EPHT drinking water workgroup assessed existing statewide and local water quality data sources. This assessment documented the availability and quality of centralized and electronic water quality and water system data that could be used to generate useful, nationally consistent measures for tracking spatial and temporal trends in drinking water quality. The results indicate that the data elements needed to generate public health based measures are centrally reported to the state agency responsible for regulating public water supplies, and are available in electronic format to EPHT programs. The most crucial data gap is the lack of information on the geographic extent and spatial distribution of water systems, making the linkage of these data with population based census estimates and other health effect data virtually impossible. The entire assessment process benefited EPHT as it provided a better understanding of the data available from different states and the feasibility to generate measures to assess drinking water quality.

Select this Article		Historical Inputs of N‐Nitrosodimethylamine to the Public Drinking Water Supply in Wilmington, Massachusetts John L. Durant, Bruce Jacobs, and Peter Shanahan ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)165 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract It has been hypothesized that N‐nitrosodimethylamine (NDMA), a potent carcinogen that is present at high levels in the ground water beneath the Olin Chemical Company site in Wilmington (Massachusetts), has contaminated the town's water supply wells. NDMA was not manufactured or used at the site, nor is it known to be a byproduct of chemical manufacturing activities at the site; thus it is suspected that NDMA precursor compounds were present in waste materials released on the site, and that the precursors then reacted in the subsurface to form NDMA. We undertook this study to establish a timeline for the release of NDMA precursor compounds into the aquifer, investigate the likely reaction mechanisms and kinetics of NDMA formation, and estimate the travel time of NDMA from source areas to the town of Wilmington's water supply wells. Based on the history of chemical waste disposal at the site, there is strong evidence for nitrosation of organic nitrogen compounds as being a major pathway leading to NDMA formation at the site. In particular, the manufacture Nitropore 5 PT, a blowing agent, required the use of sodium nitrite as one of the ingredients and produced dimethyl formamide as a waste material. Dimethyl formamide can hydrolyze to form dimethylamine, which reacts with nitrite by the nitrosation pathway to form NDMA. The kinetics of NDMA formation by nitrosation are relatively rapid (timescales of hours‐to‐days), suggesting that NDMA was formed onsite soon after the precursors were dumped there. A ground‐water model was constructed using MODFLOW to estimate NDMA travel times between the site and the town wells. The trajectories of individual particles introduced into the model at the NDMA source area were simulated assuming steady‐state hydraulic conditions. Two transport simulations were carried out based on 1965 and 1973 as being alternative estimates of the earliest production dates of Nitropore 5 PT, the suspected major source of NDMA precursors. For the 1965 simulation, NDMA started to arrive in the wells in 1971, and reached a peak concentration at the Butters Row well 1 in 1980. The 1973 simulation resulted in a 1977 arrival and a peak concentration at the Butters Row well 1 in 1983. In both cases, the wellhead concentrations of NDMA decreased from their peak concentrations, but were not eliminated entirely, due to the capture of NDMA by nearby industrial wells. Although the wells were shut off in 2003, it is suspected that chemicals in the water supply may be linked to high rates of childhood cancer. Results from this study could be useful in determining whether temporal correlations exist between NDMA in drinking water supplies and disease incidence among Wilmington residents.

back to top

ENVIRONMENTAL PERMITTING

Select this Article		Permitting an LNG Import and Storage Terminal: A Case Study Jason M. Goldstein and Rebecca F. Goldstein ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)166 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Southern LNG, Inc. (SLNG) is one of only four liquefied natural gas (LNG) import terminals currently operating in the continental United States. Because LNG import and storage terminals are a critical component of the country's diversification of natural gas reserves, infrastructure, and reliable energy services, as many as 40 LNG terminals are either before the Federal Energy Regulatory Commission (FERC) or are being discussed by the LNG industry in the United States. In 2005, SLNG initiated the Elba III Terminal Project, a major federal project requiring an extensive environmental review process pursuant the National Environmental Policy Act (NEPA). FERC was the lead federal agency responsible for coordinating the Environmental Impact Statement (EIS), with the US Army Corps of Engineers, US Coast Guard, and the National Marine Fisheries Service acting as cooperating agencies. This paper provides an overview of SLNG's experience with FERC and the cooperating federal agencies during preparation of the EIS required for authorizing the Elba III Terminal Project.

Select this Article		“Permitting of Natural Gas Wells in the Floodplain” T. Lynn Lovell, P.E., Joe Barrow, P.E., and William A. Wiegand ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)167 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract This paper describes some of the technical and regulatory issues involved with obtaining permits for the drilling and production phases of natural gas wells in the north Texas area. Natural gas well drilling in the Dallas and Fort Worth metropolitan area has increased dramatically over the past 5 years. The Barnett Shale Formation activity has increased substantially due to advanced and complex horizontal drilling techniques which allow drillers to go beneath adjacent property owners with lower or minimal surface impacts. In a study conducted by the Fort Worth Chamber of Commerce, the Barnett Shale is contributing $5 billion annually and 55,000 permanent jobs in North Texas. Fort Worth city officials estimate that over 20 years, lease bonuses will provide $742 million for municipal offers and property tax revenues from the wells could bring that total to more than $1 billion. The complexity of locating suitable urban well sites, pipelines, and production facilities is much more difficult than in rural areas. Most cities in the Dallas Fort Worth area have adopted restrictive oil and gas well drilling ordinances and regulations. Floodplains are often the only sites available that are outside of the distance limitations or restrictions for drilling near homes, parks, and other sensitive facilities. Engineers and other professionals are involved with several different phases of the Barnett Shale gas well industry which includes: 1) Permitting Natural Gas Wells in the Floodplains throughout the Metroplex; 2) Preparing GIS‐based maps to determine feasible locations for drill sites; 3) Providing route studies for pipelines; and 4) Delineation of wetland boundaries or “Waters of the US”, to be avoided by the drilling and production facilities; and 5) Field surveying gas well pad sites and lease boundaries. Much of this effort has been an attempt to guide exploration companies in minimizing the environmental impacts of this activity. The energy companies have significant political and financial resources.

Select this Article		Real‐Time Water Quality Monitoring as a Regulatory Tool for Mining Sites — The Newfoundland and Labrador Experience Amir Ali Khan, Haseen Khan, Jennifer Bonnell, and Joanne Sweeney ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)168 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract In order to assess the impact of natural resources development projects such as mines on water bodies, it is crucial to have an appropriate water quality‐monitoring program in place. Real‐time water quality (RTWQ) monitoring is suited to monitoring the impact of mining projects especially those situated in remote locations. To illustrate the successful use of RTWQ monitoring as a regulatory performance tool, case studies are presented of two real time water quality networks that were established as a part of the environmental permitting process for the Voisey's Bay Nickel Mine project site in Labrador and the Aur Resources Copper Zinc Mine site in Newfoundland. The case studies detail the need for the establishment of the networks, the installation of the networks, the details of the networks, the Quality Assurance program, the RTWQ public web page and the experience encountered since the networks were established. Also discussed is the use of the data collected by the RTWQ network by various stakeholders. The challenges of using RTWQ for mining sites are also discussed.

Select this Article		The Impact of Recent Supreme Court Decisions on Federal Jurisdiction of Streams Gary E. Freeman, F. ASCE, Ph.D., P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)169 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The relatively recent U.S. Supreme Court case that was expected to reduce confusion and shed some light on the jurisdiction of the Corps of Engineers and EPA over wetlands and streams in the United States has primarily resulted in confusion and frustration on the part of both regulators and those being regulated by the agencies. The Supreme Court decision had something for everyone — except a clear conclusion of what should be included as “Waters of the United States”. This lack of clear guidelines or a “bright line test” has led to new guidance from the Corps that attempts to apply the muddy conclusions of the Rapanos decision. The decision from Rapanos is evaluated herein and the decision presented in a way that is (hopefully) more clearly understood than the three conflicting opinions contained therein. Tables have been developed that can be used to help navigate the already muddy waters of determining which streams and wetlands are jurisdictional and which are not.

back to top

ENVIRONMENTAL PROCESSES AND TECHNOLOGIES

Select this Article		Episodic Stream Acidification in the Great Smoky Mountains National Park: An Investigation into the Mechanisms of Acidification and Impacts on Native Brook Trout Keil J. Neff, Edwin Deyton, John Schwartz, Theodore Henry, and R. Bruce Robinson ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)170 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract In 2006, 67‐km of 12 streams in the Great Smoky Mountains National Park (GRSM) were listed on the 303d list as impaired due to low pH from atmospheric deposition and unknown sources, requiring a TMDL to be developed. The GRSM receives some of the highest rates of atmospheric acid deposition in the U.S. in the form of sulfur and nitrogen oxides, which can cause stream pH to drop below 5.0 (minimum of 4.0) for 2‐days or longer. Acids enter poorly buffered streams through wet deposition and from naturally occurring organic acids and accumulated dry deposition flushed from watersheds, temporarily reducing pH and ANC in streams. Stream acidification has been shown to have damaging effects on the health of aquatic ecosystems and biota, and is suspected to be a primary cause of the extirpation of native brook trout (Salvelinus fontinalis) in six headwater streams in the GRSM. To develop appropriate TMDLs, it is imperative to understand the environmental processes associated with stream acidification, determine system responses to atmospheric deposition, and evaluate impacts to biota. The objectives of the current research are to 1) characterize the chemical constituents in stream water during baseflow and stormflow in three forested watersheds in the GRSM, 2) identify potential mechanisms responsible for episodic acidification, and 3) evaluate physiological distress in native brook trout during episodes of stream acidification. Conductivity, pH, turbidity, stage height and temperature were monitored continuously (15‐minute intervals) at three study sites using multi‐parameter data sondes. Baseflow grab samples and precipitation samples were collected; automatic water samplers captured stormflow samples. Stormflow, baseflow, and precipitation samples were analyzed for pH, ANC, trace metals, and major cations and anions. To provide evidence that native brook trout are impacted by stream acidification, in situ bioassay experiments were conducted. Changes in native brook trout physiology were determined during two acid runoff episodes. Brook trout were put in cages at the three sites and fish were sampled before and after stream acidification events. To assess physiological stress in brook trout as a response to acid conditions, whole‐body sodium concentrations of individual fish were evaluated. ANC and pH depressions were observed during all stormflows at the three study sites. Sulfate, nitrate, and organic acid concentrations increased during runoff episodes. Base cation concentrations generally increased during stormflow at two stream sites, but diluted occasionally at the third site. The relative changes in ion concentrations were used to determine which ions (acids) were most responsible for ANC depression. ANC contribution analysis indicates acid deposition may be the primary cause of episodic stream acidification, but it appears organic acids and cation dilution may also contribute. Results of the in situ bioassay demonstrate that stream acidification can negatively affect native southern brook trout physiology in the GRSM under actual field conditions. Trout lose the ability to regulate critical blood ions, as exemplified by a loss of whole‐body sodium, when stream pH dropped below 5.1.

back to top

MEMBRANES IN WATER AND WASTEWATER TREATMENT

Select this Article		Membranes in Water and Wastewater Treatment Val S. Frenkel, Ph.D. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)171 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Membranes are becoming an important commodity in water and wastewater treatment. There are four major membrane categories, classified by membrane pore size, that are commercially used at the present time: Microfiltration (MF), Ultrafiltration (UF), Nanofiltration (NF) and Reverse Osmosis (RO). All four membrane categories are commonly used in water and wastewater treatment to achieve the goals of Drinking Water Guidelines and Standards. They are also used to produce desalted and/or Ultra Pure Water (UPW) for different industrial and other needs, such as power plant make up water, electronic chips manufacturing, food industry, pharmaceutical, medical and others. Membranes in wastewater treatment have lagged behind membranes used in treating water. However, the wastewater market area is growing fast, benefiting from the experience and technology issues that water applications have overcome. Nearly every known conventional water treatment technology and process has a membrane equivalent. For example, clarifiers and media filters can be successfully replaced by MF or UF membranes, softening with Cold Lime or Softeners can be achieved by substituting NF membranes, and ion exchange units can be replaced by RO membranes. Even mixed beds ion exchangers have a replacement membrane equivalent: Electro‐Deionization (EDI) technology can achieve the strict standards required to produce ultra pure water (UPW) for the needs of the power and semiconductor industry. The proper and most efficient water treatment process for a particular facility has to be selected based on the specific project conditions, technical requirements, and economical parameters (capital and O&M cost). That is why the majority of membrane applications presently on the market are combinations of conventional and membrane technologies. However, a growing number of water treatment systems contain membrane processes only (membrane and/or integrated membrane system). One efficient application of membrane technology is the upgrade of existing operational plants. By implementing membrane technologies, the plant's system size (water flow), and effluent quality can be upgraded significantly at a lower relative cost than achieved by applying conventional treatment only. Most conventional processes require more chemicals to operate the system, while membrane technologies are “cleaner” processes. This presentation provides a brief history of membranes, presents the characteristics of the different types of membranes, and discusses the exponential growth in the number of installations. It will also cover applications for water recycling, water reuse and desalination, and the challenges that membrane treatment processes face. This presentation will conclude with a discussion of recent membrane developments and how these developments may impact the future of membrane applications Information provided in this presentation may help Engineers, Utilities, and Government and Private Sector representatives better understand the features and applications of membrane technologies, membrane selection and differences, evaluation and design concepts, procurement of membrane equipment, and balance of the treatment plants.

Select this Article		Stress Effects on Fouling of Flat Sheet Membrane Bioreactor Treating Biodegradable Wastewater Kripa S. Singh, Z. Mi, and S. R. Grant ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)172 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Two laboratory‐scale flat sheet membrane bioreactors (FSMBR) with three flat sheet membrane cartridges in each were set up to treat a synthetic biodegradable industrial wastewater. Four stress conditions were employed during the study including different organic loading rates (OLR phase), high salt concentration (salt phase), temperature spikes (temperature phase), and mixed liquor suspended solid (MLSS) concentration (MLSS phase). This study investigated the impact of the stress factors on membrane fouling and evaluated the performance of the FSMBR. Under the imposed stress conditions, the experimental reactor had a smaller particle size, higher average effluent COD concentration, and lower sludge filterability. The experimental reactor also fouled at a faster rate than the control reactor. The results showed that imposed stress conditions had an effect on the bacteria in the MBR which impacted sludge characteristics such as filterability, polysaccharide production, floe size, effluent COD concentration, effluent color, and most importantly the rate of membrane fouling.

Select this Article		The Hybrid Membrane Biofilm Process for TN Removal from Wastewater: Bench and Pilot Scale Studies Leon S. Downing, Kyle J. Bibby, Tom Fascianella, Kathleen Esposito, and Robert Nerenberg ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)173 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The hybrid membrane biofilm process (HMBP) is a new approach to achieving total nitrogen removal from wastewater, with great potential for retrofitting into existing plants. It incorporates air‐supplying hollow‐fiber membranes into a conventional activated sludge tank. The HMBP utilizes both attached and suspended growth to achieve TN removal. At the bench scale, the performance of the HMBP was assessed for a variety of nitrogen and BOD loading rates. The nitrification rate remained at approximately 1.0 gN m⁻² d⁻¹ despite BOD loadings ranging from 4 to 17 gBOD m⁻² d⁻¹ at a nitrogen loading of 1.7 gN m⁻² day⁻¹. Denitrification rates of 100% were achieved when sufficient BOD was available in the influent. Microsensor measurements indicated nitrite was the dominant form of oxidized nitrogen produced by the biofilm, showing that shortcut nitrogen removal was taking place. Fluorescence in‐situ hybridization (FISH) tests on the biofilm revealed a unique stratification, with three distinct regions: AOB and NOB near the membrane, strictly AOB at intermediate depths, and AOB and heterotrophs at the outer edge of the biofilm. Pilot scale studies with municipal wastewater primary effluent (PE) indicated a reduced nitrification rate. With an average nitrogen loading rate of 0.6 gN m⁻² day⁻¹, the average nitrification rate was 0.4 gN m⁻² day⁻¹, with a maximum of 0.6 gN m⁻² day⁻¹. These rates are similar to aerobic fixed film systems (i.e., RBCs). However, unlike other fixed‐film systems, reduction of nitrate/nitrite to below 1 mgN/L was consistently achieved in the pilot scale HMBP, without the need for an exogenous electron donor.

back to top

SITING AND PERMITTING OF NEW NUCLEAR POWER PLANTS

Select this Article		Expanding Existing Nuclear Plants: The Impact on the Thermal Performance of a Cooling Reservoir Periandros Samothrakis, M. ASCE, Yifan Zheng, M. ASCE, David Ugolini, and Patrick Ryan ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)174 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A study is performed to analyze the thermal performance of a cooling reservoir of an existing nuclear power plant with the addition of two new units. For the analysis, a one‐dimensional multi‐layer computer program is used. The program simulates the transient response of the cooling pond under imposed heat loads for the site historical meteorological conditions and plant operating conditions for specified pond characteristics. These results are used to investigate different condenser/circulating water system design parameters and determine the optimum parameters for the cooling water system for the expansion of the nuclear plant.

Select this Article		Probable Maximum Precipitation Flooding Analysis for Nuclear Power Plant Permitting Craig. J. Talbot, M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)175 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Recently, many electric power generation companies have a renewed interest in the development of new generation nuclear power plants. In response to that interest, several Early Site Permit and Combined License applications have been submitted to the Nuclear Regulatory Commission (NRC) seeking permits for new nuclear power plants. The application process requires the submittal of a Safety Analysis Report (SAR) for the site and power plant. The Safety Analysis Report requires probable maximum precipitation (PMP) flooding analysis for adjacent streams and rivers as well as local site drainage. Procedures and guidance from the NRC and others are presented for PMP flooding analysis on river watersheds. The presentation is based on analysis performed for recent applications to the NRC as well as the NRC's independent PMP analyses that were preformed to evaluate the applications. Specific topics addressed are the spatial and temporal development of the PMP for a watershed, runoff analysis and calibration of runoff analysis, flood routing, combined events criteria, water level determination, and NRC independent analysis approach.

Select this Article		Two‐Dimensional Embankment Breach Analysis Yonas Kinfu and Kit‐Yin Ng ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)176 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A two‐dimensional embankment breach analysis was conducted to estimate the postulated worst case flood levels to support the combined operation and construction licensing of a nuclear power plant. A multi‐dimensional hydrodynamic model, Delft3D‐FLOW, was used to simulate flooding from an instantaneous breaching of the embankment of an on‐site cooling reservoir with a surface area of about 7,000 acre (2,800 hectare) and an average height of 40 ft (12.2 m). The Delft3D‐FLOW feature for solving rapidly varying flows (“Flooding scheme”) was utilized for the analysis. The results capture the water level variation due to the initial flood wave impact on the safety‐related power buildings and the subsequent quasi‐steady state flooding conditions that prevail for a few minutes. Various tailwater conditions (including dry bed) were analyzed to determine the critical flood level to be used as the design basis for the safety related facilities of the nuclear power plant.

back to top

SOLID AND HAZARDOUS WASTE MANAGEMENT

Select this Article		Enhanced Leachate Recirculation at Dallas' McCommas Bluff Landfill Fred J. Doran, P.E. and Ron Smith ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)177 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Termed the largest “recycling” project in Texas, the City of Dallas is currently developing a enhanced leachate recirculation (ELR) project at the McCommas Bluff Landfill (Landfill). As one of the largest municipal solid waste (MSW) landfills in the Country, it typically receives 7,000 tons of MSW per day and supports a 5‐million cubic feet per day high‐BTU landfill gas (LFG) processing facility. The landfill's enhanced waste degradation could result in the destruction of up to 40‐percent of the in‐situ waste volume; hence the largest “recycling” project. The City recently completed the permit stage for this project. In early 2008, the City will begin placement of waste in Cell 6, the first cell permitted for ELR. Installation and operation of the first lift of recirculation laterals and gas collectors will take place throughout 2008. Conceptual design factors include: 1 Bioreactor type (anaerobic, aerobic, or hybrid). 2 Leachate or added liquid pretreatment, storage, and delivery. 3 Liquid application methods. 4 Odor control. 5 Innovative LFG collection in wet waste. 6 Cover soils and liner design.

Select this Article		Modeling Water Balance for a Demonstration‐Scale Alternative Landfill Cover in Hawaii Laxman Sharma and Chittaranjan Ray ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)178 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A problem associated with landfills is the production of leachate, caused by water infiltrating into the disposed waste material, and the migration of it from the landfill with various contaminants. The solution to this is to reduce infiltration, which reduces the leachate production. Vegetative covers are an attractive method in the arid regions using evapotranspiration to reduce the amount of water seeping into the landfill. In the tropics, where rainfall exceeds the potential evapotranspiration, runoff enhancing mechanisms can be used to minimize infiltration and leachate generation. An experimental landfill cover site with rain gutters placed as runoff enhancing mechanism had been established at the Marine Corps Base Hawaii in Kaneohe, Hawaii to monitor different components of the water balance in three different treatments — control, 20 % and 40 % coverage with gutters. A rain simulator was also used to augment the natural rain episodes to obtain a wider range of rainfall intensities. While both the 20% and 40% covered areas produced lower amounts of leachates than the control plot, the 40 % covered area did not produce the expected (lesser) amount of leachate. The gutters were more effective in high intensity rainfalls than in low intensity ones. These observations suggest that interception by vegetation overhanging into the gutters might have reduced runoff generation. The Hydrological Evaluation of Landfill Performance (HELP) model was used to study the leachate and the runoff generated. The simulated results overestimated the leachate generation in agreement with the understanding that daily averaging of rainfall should increase the leachate volume. Additional event based modeling are also under progress to look at the process in detail.

back to top

WASTEWATER TREATMENT I

Select this Article		Biodegradation of a Food Processing Wastewater Utilizing Phanerochaete Chrysosporium Anastasia E. M. Chirnside ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)179 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Soybean hulls are processed into soy flour in a method similar to paper mill production. During the process, the soybean hull wastewater (SHW) is discharged into an anaerobic lagoon and then into an aeration basin. From there, it passes to a facultative lagoon before discharge. Even after this conventional treatment, the SHW has extremely high amounts of Total Kjeldahl Nitrogen (TKN), Chemical Oxygen Demand (COD) and a high pH. We have developed an attached growth, packed‐bed bioreactor (PBR) containing the white rot fungus (WRF), Phanerochaete chrysosporium. This fungus secretes enzymes that catalyze oxidation reactions that result in degradation of recalcitrant compounds such as PCB, PCP, and pesticides. Previous studies utilizing the fungus in a bioreactor found that it could decolorize a polymeric dye. We hypothesize that the WRF could degrade the SHW and reduce the TKN and COD. We also assessed the effectiveness of pH adjustment of the SHW before introduction into the bioreactor. The objectives were to evaluate the ability of P. chrysosporium grown in a PBR to degrade the SHW containing high concentrations of TKN and complex organic compounds and to investigate the effectiveness of pH adjustment of the SHW before treatment in the PBR. The WRF in the PBR was fed an N‐limited media for 5 days before introduction of the SHW. The effluent was sampled daily and measure for TKN, COD and pH. The pH adjusted wastewater was recycled through the PBR and the effluent was sampled daily and measure for TKN, COD and pH. Within 48 hours, 63% of the TKN and 37% of the COD was degraded. The pH of the effluent increased steadily from an initial pH of 4.88 to 8.59 at 24 hours. Within 72 hours, the effluent pH was equal to the influent pH. At this point, degradation within the PBR ceased. Continuous adjustment of pH during recycling of the wastewater within the PBR resulted in an increase in the amount of TKN and COD degraded. Over 90% of the TKN and approximately 33% of the COD was removed during treatment within the PBR. The pH of the SHW in the PBR had a significant effect on fungal degradation. The reduction of COD was more sensitive to pH changes than the reduction of TKN. With the improved pH control in the PBR during recycling events, a greater amount of TKN and COD were removed from the wastewater. These positive results indicate that treatment of recalcitrant wastewater with the WRF deserves further investigation.

Select this Article		Investigation of Denitrification Kinetics Using Various Carbon Sources in Sequencing Batch Reactors at Cold Temperature Yalda Mokhayeri, Jeneva Hinojosa, Rumana Riffat, Sudhir Murthy, Imre Takacs, Peter Dold, and Charles Bott ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)180 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Facilities across North America are designing plants to meet stringent limit of technology (LOT) treatment for nitrogen removal. This is in response to the Chesapeake Bay Agreement, which will limit effluent total nitrogen to 3 mg/L. Of particular interest is the use of an alternate external carbon source to replace the most commonly used carbon, methanol. Replacing methanol with an alternate external carbon source for denitrification in the winter will be particularly important since methanol utilizer growth is stunted during colder temperatures. This study focuses on three external carbon sources: methanol, ethanol and acetate. The aim of this study was to obtain the specific denitrification rate (SDNR) of the substrates in two different contexts. Sequencing batch reactors (SBRs) were set up to acclimate carbon free biomass to the specified substrate while in‐situ SDNRs were conducted concurrently. Once the biomass was acclimated to the corresponding substrate, a series of ex‐situ SDNRs were performed using various biomass/substrate combinations. All experiments were conducted at 13°C. The results suggest that the SDNRs for acetate (32 mgNO₃‐N/gVSS/hr) and ethanol (30 mgNO₃‐N/gVSS/hr) are higher than that for methanol (9 mgNO₃‐N/gVSS/hr). Ethanol acclimated biomass fed with acetate resulted in the highest SDNR of 26 mgNO₃‐N/gVSS/hr.

Select this Article		Sulphate Reduction in a Three‐Stage Packed‐Bed Anaerobic Bioreactor M. Borghei and Q. Poorhashem ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)181 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract In this paper the effect of the sulphate concentration on the performance of a three‐stage anaerobic baffled packed‐bed reactor (ABPR) was investigated. Synthetic wastewater (3000 mg COD/l) was used as the sole organic substrate. The 30 liters fixed‐bed bioreactor filled with plastic packing and divided in three equal sections was used as the mABPR reactor. The unit was run at a hydraulic retention time (HRT) of 1 day and at temperature of 25° C. The results of this study showed that when COD/SO4^2⁻ ratios were changed from 30 to 3 with increasing sulphate concentration from 100 to 1000 mg/l, COD removal slightly was decreased. Maximum COD and sulphate removal were 91 and 96%, respectively, where more than 50% of this removal occurred in first compartment in the whole experiment. Overall sulphate concentration had little effect on the efficiency of organic removal and the anaerobic reactor performed well under various conditions, tolerating high concentration of sulphate.

back to top

WASTEWATER TREATMENT II

Select this Article		Collaborative International Research: Technology Transfer & Efficiency of Wastewater Treatment Systems in Rural Communities of Bolivia Meredith M. Ballard, Abigail R. Clarke, Afton Sather‐Knutsen, Brian D. Barkdoll, and James R. Mihelcic ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)182 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract There has been increased recognition that the world faces serious challenges in terms of long‐term economic growth, societal prosperity, and environmental protection. In particular, health problems resulting from environmental risks and a lack of economic resources in the developing world pose daunting challenges to the global scientific and engineering communities. Addressing these challenges through international research experiences integrated with sustainability and appropriate technology principles represents a significant and critical contribution to a more sustainable future. This paper describes a National Science Foundation‐supported international research partnership that helps address sustainable development through increasing global access to adequate water and sanitation. The partnership consisted of seven undergraduate and graduate students from Michigan Technological University, six undergraduate environmental engineering students from Bolivian Technological University (UTB), and technical staff affiliated with a non‐governmental organization, ACDI‐VOCA (Agricultural Cooperative Development International and Volunteers in Overseas Cooperative Assistance). The Michigan Tech students were studying environmental engineering, civil engineering, mechanical engineering, and environmental policy. Wastewater treatment systems located in three small rural communities (Palos Blancos, Sapecho, and San Antonio) were studied. These three systems include: 1) a septic tank with anaerobic filter, 2) an Upflow Sludge Blanket Reactor with stabilizing lagoons, and 3) a stabilization‐lagoon system respectively. Detailed water quality analyses were performed at each plant and performance was compared with the projected performance from the original design. System efficiency was evaluated in terms of cost, treatment effectiveness, and maintenance. Additionally, interviews with water committees were completed to determine what understanding of the system was conveyed when the technology was transferred from the design and construction stage to the community. Results showed that only two of three systems were functioning due to failure in operation, low capacity, insufficient funds for maintenance, system over‐design, and the lack of knowledge base about the system from the community. Plant performance appears to be strongly influenced by the knowledge base and lack of funds for each water committee. Recommendations were made for greater ease in community ownership of constructed wastewater treatment systems. This collaborative research effort produced an intensive cultural exchange and inter‐disciplinary collaboration demonstrating developing communities' reasons why systems under‐perform.

Select this Article		Determining the Optimized Hydraulic Retention Time in the USBF Reactor for Biological Phosphorus Removal S. Fartoos, H. Ganjidoost, and B. Ayati ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)183 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract This research describes an experimental technique which has been used to determine the efficiency of the USBF process in organic matter reduction and phosphorus removal. Continuous feeding of synthetic wastewater was used in different hydraulic retention times to access the optimized HRT according to the phosphate removal capacity of the USBF pilot and the sludge quality. HRTs varied from 16, 14, 12, 10, 8, 6 and 4 hours for the settling compartment, with the COD/P ratio remaining around 50, while the PO₄³⁻‐P concentration was about 20 mg/l. The experiments were performed at pH between 6.5–7.8 and at room temperature (i.e. 20±2 °C). The results of the experiments showed that the test system was efficient in removing COD and P in more than 85 percent of the cases for all of the tests after 20 days. The best results for P removal were obtained at the HRTs less than 8 hours while the Sludge Volume Index (SVI) was more than 150ml in lower HRTs as 6 and 4 hour. In the statistical analysis done to explain the results, it is revealed that with the differing parameters of P removal efficiency, SVI and the Total Suspended Solid (TSS), the optimized HRT for the Settling compartment is 10 hours.

Select this Article		Optimal Design of the Chicago Calumet Water Reclamation Plant (CCWRP) Primary Settling Tanks with 3D Numerical Models Xiaofeng Liu and Marcelo H. García ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)184 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A three‐dimensional numerical model was developed for the proposed primary settling tank (PST) for the Calumet Water Reclamation Plant (CWRP) in Chicago, IL. The numerical model can deal with three‐dimensional multi‐phase turbulent flow. Two‐fluid model is used to capture the behavior of the solid‐water mixture. Hindered settling was modeled by an empirical exponential relationship between the settling velocity and the solids concentration. The sludge was modeled as a Bingham plastic with parameters estimated from experiments. During the design, the most important parameters are the tank's depth and diameter. These two parameters are also the controlling factors for the construction cost. Other parameters include the inlet/outlet structure, feed well depth/diameter, bottom slope, etc. The tank diameter is fixed due to the space restriction. The tank depth and feed well depth were analyzed by comparing different options. Once these two parameters were fixed, other parameters were fine tuned to optimize the performance of the tank. Due to the length of this paper, only the simulations for the tank depth and the feed well depth are introduced.

Select this Article		Use of CFD Modeling for Predicting Contact Time and Improving Hydraulic Conditions in a Chlorine Contact Tank Fangbiao Lin, Ph.D., Juan C. Josse, and Arseny Kalinsky, P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)185 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Traditionally, contact time of a chlorine contact tank (CCT) is determined by performing field tracer tests. This paper presents an alternative of using computational fluids dynamics (CFD) modeling to predict the contact time. This method is known as numerical tracer testing. Field tracer tests require maintaining constant flow through the CCT, chemical injection at the inlet, and continuous sampling. Typically three or more tests must be conducted at different flows to create flow‐contact time curves. These requirements are difficult to meet in potable or wastewater treatment plants in operation; the tests are cumbersome and require significant operator effort. Numerical tracer testing facilitates the task without operation interruptions or complex set‐ups. Numerical tracer testing was used for determining the contact time at the Irvine Ranch Water District's (IRWD) Michelson Water Reclamation Plant CCT in Irvine, California. The CCT is a two‐million gallon, four‐pass baffled tank capable of handling up to 20 mgd of tertiary filter effluent. CFD results were compared to field data obtained with a step‐feed field tracer tests using lithium chloride. The comparison shows that CFD modeling is capable of accurately predicting contact times in the CCT. CFD modeling was used then to perform step‐feed and slug‐feed tracer test simulations at different flows in order to obtain T₁₀ and modal contact times. CFD modeling was also used for predicting flow patterns in the CCT. Results of CFD modeling, including flow streamlines, velocity contours and vectors, were used to improve velocity distribution and reduce solids deposition, short‐circuiting and vortices with the inclusion of baffles. The study demonstrates that CFD modeling is a valuable modeling tool for the water and wastewater industry.

back to top

WATER AND WASTEWATER REUSE

Select this Article		Analysis of Washout Water for Reuse within the Concrete Industry with the Aid of Chemometrics L. McCarthy, S. Kokot, R. Frost, G. Carson, and R. Gustkye ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)186 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Within Australia water for use in concrete must be potable. However, ever increasing demands on water are depleting the available resources. Whilst it is currently thought that concrete properties are highly influenced by the water type used and its proportion in the concrete mix, there is little knowledge of the effects of different, alternative water sources used in concrete mix design. One such water source, recycled wash water is currently used by batch plants as mixing water for concrete. This comprehensive study of suitable water sources aimed to gain a better understanding of the current water reuse and recycle techniques and the subsequent characteristics of the wash water each produced. The quality of the waters collected was monitored with the standard Internal Readymix Variables such as SO₄²⁻, Cl⁻, TDS and others. Their influence, on fresh, hardening and hardened concrete properties was investigated by measuring the compression strength and shrinkage of individual concrete cylinders prepared with the use of these waters over a ten week period. The use of Principal Component Analysis indicated that the physical propoperties of concrete are unaffected by the different waters provided that the water quality was within the specified standard limits. A relative rank order of the water samples was obtained with the use of the PROMETHEE ranking chemometrics and this can be applied for comparative to future recycled water quality applications.

Select this Article		Applying Surrogates to Determine the Efficacy of Groundwater Recharge Systems for the Removal of Wastewater Organic Contaminants Eric Dickenson, Jörg E. Drewes, Shane Snyder, and David Sedlak ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)187 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Many utilities are currently using drinking water sources impacted by wastewater discharge and others are planning for or implementing indirect potable reuse via groundwater recharge systems. The use of water sources impacted by wastewater has raised public concerns due to the presence of trace organic contaminants. Many wastewater‐derived organic compounds are often present at extremely low concentrations and no standardized analytical methods are available. This study proposes that simple to measure surrogates (bulk parameters) and indicators (individual organic compounds) can be used together to assess the performance of soil aquifer treatment and membrane systems treating recycled water containing wastewater‐derived organic contaminants. Potential surrogates and indicators were identified and validated in the field at full‐scale soil‐aquifer treatment and membrane systems.

Select this Article		Zero-Discharge Treatment System for the Wastewater from Scenic Environmental Sensitive Communities C. S. Rocky Shih, Michael W. Thomas, and Anna M. Doro-on ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)188 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The “Zero-Discharge” Wastewater Treatment System has been advocated for the scenic and/or historically preserving tourism spots. The Decentralized Wastewater Treatment (DWT) coupled with the Land Treatment Method has been found to be the most effective treatment system to achieve such historically unachievable “Zero-Discharge” dream. The DWT, normally also referred as aerobic onsite or clustered wastewater treatment system, is installed to provide efficient treatment for group of residential dwellings and businesses in sparsely distributed community. It has been reported that the performance of commercially manufactured DWT is adequate in some cases but its reliability is questionable. In reality, the roots of its lack of reliability, is caused by the inappropriate handling and disposal of treated effluent. The objective of this paper is to present an innovative sustainable design approach for DWT based on extended aeration principles and complete effluent utilization by land treatment. The integrated design approach, presented herein, has also incorporated the following considerations: environmental sustainability, protection against the contamination of surrounding environment, commercial viability, minimum maintainability, and the minimum amount of sludge production. Engineering design details for both DWT's with and without separate settling basin in compliance with the current regulatory requirements have been developed and will be presented. In order to illustrate the applicability of developed self-sustainable designs, real world examples will also be presented.

back to top

WATER CONSERVATION AND TREATMENT

Select this Article		Cost Recovery and Conservation of Residential Water Use by Optimized Block Pricing Hugo A. Loáiciga ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)189 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A method for pricing residential municipal water with increasing rate structures is developed and applied in this article. The method relies on the water‐use functions for each block of a rate structure and on economic and water‐supply data to produce a nonlinear programming problem whose objective function is the recovery of water‐production costs. Maximum‐water use, minimum‐water use, cost‐recovery, and price constraints were imposed on the objective function to complete the rate‐design nonlinear programming problem, whose solution yields the block prices and water‐meter charge of a water‐rate structure. The water‐pricing method is applied to a small municipality —on the order of 90000 residents— whose water‐use functions were derived from data collected during the 1988–1991 California drought. The water‐pricing method produced a rate structure that complies with specified constraints and recovers water‐production costs, demonstrating that it is a useful tool for residential water pricing.

Select this Article		Hydro‐Economic Analysis of Water Supply for Baja California, Mexico J. Medellin‐Azuara, L. G. Mendoza‐Espinosa, J. R. Lund, M. ASCE, C. Waller‐Barrera, and R. E. Howitt ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)190 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract This paper describes a hydro‐economic analysis of agricultural, environmental and urban water supply alternatives for years 2025 and 2080, in Baja California. Alternatives include idealized water markets, wastewater reuse, seawater desalination and infrastructural expansions. A network of the water system was built to considering hydrology, agricultural, environmental and urban demands, infrastructure, economic values of water and operating costs. Wastewater reuse with other projected infrastructure expansions are overall the most economically optima alternatives. Markets offer leverage and flexibility for the future urban needs for locations with the proper infrastructure. Worthwhile expansions include a larger aqueduct to convey Colorado River water to the west. At current water price and operating costs, seawater desalination is uneconomical. Wastewater reuse for restoration is also an economic source of instream flows, with institutional arrangements on a subsidized water price. Hydro‐economic analysis is useful to better understand water‐related issues in Baja California and provide a technical basis for developing and comparing long‐term water management solutions.

Select this Article		Phosphorus Removal from Lake Water by Combined Dosage of Ferrous Iron and Diatomite Wenhui Xiong and Jian Peng ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)191 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Effective technology and approaches for reducing phosphorus concentration in the lake water are essential to control cyanobacterial bloom and lake eutrophication. This study investigated the effectiveness of the combined usage of ferrous iron (FeCl₂) and diatomite for the phosphorus removal. Several combinations of FeCl₂ and diatomite in various ratios were tested. Higher amounts of phosphorus were removed from water by the combined usage of FeCl₂ and diatomite than that by FeCl₂ alone. The optimum diatomite to FeCl₂ ratio resulting in the highest efficiency was 0.8. Alkalinity and pH of lake water treated with the combined usage of FeCl₂ and diatomite decreased less than that treated by FeCl₂. The higher P removal efficiency achieved by the combined usage of FeCl₂ and diatomite can be explained as that dissolved silica provided by diatomite was incorporated into the crystalline structure of iron oxide during the ferrous oxidation and thus silica‐stabilized ferrihydrite was formed. Silica‐stabilized ferrihydrite was an effective phosphorus adsorbent and long‐term phosphorus sink. However, ferric oxide formed without dissolved silica was transformed into more crystalline ferric oxide and then phosphorus would be released back to the lake water during this transformation. Diatom growth was stimulated by the increased dissolved Fe and dissolved Si which was provided by diatomite. The stimulated diatom growth can further uptake phosphorus following the phosphorus adsorption by the silicate stabilized ferrihydrite. It was concluded that the combined usage of FeCl₂ and diatomite is an effective approach for improving the chemical precipitation of phosphorus by FeCl₂.

back to top

WATER DESALINATION AND CONCENTRATE MANAGEMENT

Select this Article		Desalination of Bay Water Val S. Frenkel, Ph.D., Todd Reynolds, and Jean Debroux ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)192 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The Marin Municipal Water District (MMWD) Seawater Desalination Pilot Program was a successful year‐long desalination pilot study of advanced pretreatment and SWRO technologies for desalting water from San Francisco Bay (Bay) from June 2005 to May 2006. Based on the favorable outcome of the pilot program, it was confirmed that seawater desalination can be a local, reliable drought‐proof source of drinking water supply for Marin County, California. The MMWD SWRO Program provided preliminary design criteria for a full scale desalination facility, provided data to refine full‐scale plant cost opinions, demonstrated the high quality of the desalinated water and facilitated essential environmental studies for a future full scale project. A primary objective of the pilot testing program was to compare the performance of high rejection seawater RO membranes with two different pretreatment alternatives: MF/UF and conventional pretreatment. The pilot program also included analytical testing of over 100 regulated and 500 non‐regulated constituents in the Bay water and RO permeate, as well as an evaluation of second pass RO to meet MMWD's stringent finished water boron and sodium requirements. Environmental studies conducted in conjunction with the pilot testing included fish entrainment studies, bioassay studies and California Toxics Rule analysis of the brine discharge and toxicity analysis of the residuals from the pretreatment systems.

Select this Article		Present Situation and Control Research of Coastal Saline‐Alkali Fields in China Ding Yong, Xu Shi Guo, Xu Xiangzhou, Zhao Qian, and Zhang Bailiang ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)193 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract With the fast economy development in coastal regions, China, some water and soil environmental problems appear, such as that salt water fill in the soil where is fill‐building fields, sea water invading into inland while groundwater decrease, and so on. In these areas, the eco‐environmental conditions and underground constructions are impacted by the soil saline‐alkali. This study presents the control measures of Coastal Saline‐alkali Field Control, of which the main contents are as follows:(1) to understand the reasons of Saline‐alkali formation, (2) to develop the control measures including: water conservancy, vegetation methods, biologic and chemical measures, etc. (3) to analyze the economic, social and environmental benefits generated by meliorating Saline‐alkali soil. However, the relations between the soil salinization and the natural or human influence are not clear. What we need to do is to develop new desalination measures, such as making full use of rainwater during flood seasons, and carry on benefit recognition and quantitative evaluation for the benefit brought by meliorating Saline‐alkali soil.

Select this Article		So Maui, ‘What Would You Do with the Concentrate?’ Raymond N. Matasci, P.E. and Mike Mickley, P.E., Ph.D. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)194 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Maui is experiencing significant population growth in its most water‐short areas in Central and South Maui. Recently, the feasibility of using desalination to provide alternative supplies to meet future needs has been studied. The Maui Department of Water Supply determined a 5‐mgd brackish water Reverse Osmosis (RO) facility was feasible in Central Maui. A private developer is planning on a 1.5‐mgd brackish water RO facility to meet potable water needs for a 670‐acre, 1400‐unit development in South Maui. For desalination projects, one of the toughest questions to answer is “What would you do with the concentrate?” For both projects, various concentrate management alternatives were evaluated including surface water discharge, disposal to sewer, evaporation ponds, subsurface injection, and land application. For the 5‐mgd Central Maui facility, subsurface injection was determined to be the best option because of its simplicity, low cost, and ease of implementation. For the 1.5‐mgd South Maui facility, land application through irrigation was determined to be the best option because of the relatively high quality concentrate and the opportunity to blend with other source waters (recycled water and brackish water) to meet a large irrigation demand (golf course).

back to top

WATER TREATMENT

Select this Article		Development of an Algorithm for Evaluation of a Water Treatment Plant Performance Mohammad Karamouz, F. ASCE, Hamed Tavakoli far, Sara Nazif, and Kabir Rasouli ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)195 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Water Treatment Plants (WTP) have a key role in water supply with adequate quantity and quality in desired pressure condition. Sustainable performance of these systems is very important and quantifies the readiness of them especially in critical conditions. System readiness is one of the main issues that water users, stakeholders and decision makers of water resources consider in order to decrease the probable damages. In this paper, a methodology for assessment of a WTP performance has been proposed. This methodology quantifies the readiness of the system in different stages of plant's operation. For this purpose, three system operation indices including reliability, resiliency and vulnerability are considered. Due to the differences between the indices and especial characteristics of them, a hybrid index of them can be a good indicator of the system performance. In this study, the mentioned indices have been hybridized considering the importance of water shortages in system readiness evaluation utilizing Artificial Neural Networks (ANNs). In order to evaluate a WTP performance, the proposed hybrid index is developed. It is categorized into different levels for assessing the system readiness in critical conditions. The proposed methodology has been applied for a WTP in Tehran metropolitan area in Iran. The Results show that this algorithm can be effectively used for evaluation of the WTP performance.

Select this Article		Gas Transfer Inside a Deep Airlift Reactor J. P. Giovannettone and J. S. Gulliver ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)196 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Airlift reactors with a bubbly flow are commonly used to add oxygen to the hypolimnion of lakes. However, there is no reliable information on the gas transfer that will occur in a field‐scale airlift reactor. Gas transfer experiments are conducted inside a deep bubble column/airlift reactor containing air and water with a maximum aerated water height of 23.4 meters and diameter of 1.06 meters. The effects of geometry and operating conditions on gas transfer are determined. A two‐phase convection‐dispersion model is fit to the DO measurements using the liquid film coefficient (K_L) as a fitting parameter. Sparger differences had a substantial effect upon K_L, and the gas transfer coefficient for the airlift reactor was four times that of the bubble column. Results are characterized using Sherwood, Reynolds and Bond numbers. A low Reynolds number exponent was found, indicating that K_L in a deep column tends towards a constant and is not highly dependent upon air discharge.

Select this Article		Performance of Water Treatment Plant Elements Sarker Rahman and Tarek Zayed ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)197 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Potable water treatment is one of the most challenging and complex systems that municipalities need to deal with considering limited resources. The average age of continuously deteriorating Canadian water supply system was 36 years and that would require 3.1 billion dollar to bring the system at satisfactory level. Operators have little attention to plant infrastructure and equipment compared to water quality and day‐to‐day operational activities. Water treatment plant (WTP) includes several elements, such as tanks, basins and pumps. Essential condition parameters are selected including technical, physical, environmental, and operational aspects of WTP. Data on the WTP conditions are collected from experts and consultants in this domain. The targeted experts were operators, designers, consultants, regulators and researchers across Canada and few from abroad. To determine the condition index of a WTP element, value additive multi‐attribute theory (MAUT) has been used where average weights and scores are considered. It is concluded that the average condition index for settling basin ranges from 9.6 (best scenarios) to 1.9 (worst scenarios) and from 9.6 to 3.4 for pumps of WTP. Analysis reveals that, for tank and basins, design and construction stage is the most important parameter to the WTP condition. On the contrary, operational parameter is the most important for pumps. The study also highlights durability issues and details in structural design as the most important parameters for future condition of tanks and basins. However, operation and maintenance practice are the most important parameters for pumps.

back to top

COMPUTATIONAL HYDRAULICS AND HYDRODYNAMICS: I

Select this Article		Hydrodynamic and Transport Model for the Lake Michigan Coast around Milwaukee Hector R. Bravo and Peter N. Shedivy ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)198 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The nested models simulate flow and transport in the Lake Michigan coast around Milwaukee, have alongshore and cross‐shore dimensions of 45.5 km and 12 km, and maximum depth of 25 m. The alignment of the open lake boundary is important because the boundary condition formulation may introduce perturbations when oblique velocities cross the boundary. Aligning the open boundary parallel to an isobath caused negligible perturbations. The models yielded a good reproduction of measured currents and an adequate reproduction of vertical temperature profiles. The alongshore currents are approximately ten times larger than the cross‐shore currents. Local wind direction is an insufficient predictor of flow direction. The lake circulation pattern sometimes causes the flow near Milwaukee to split into counter‐rotating eddies. Preliminary results of the transport model reveal that along‐shore transport dominates over cross‐shore transport and a complex transport pattern inside the Milwaukee Outer Harbor when the currents through the breakwater gaps change direction.

Select this Article		Simulations of Saline and Turbid Gravity Currents Using a Subgrid Model Jaswant Singh, Weiming Wu, and Sam S. Y. Wang ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)199 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract This paper presents the simulations of saline and turbid gravity currents using a subgrid model, which considers the effect of density stratification on the eddy viscosity. The saline gravity current simulated here is the intrusive current in a reservoir with two layers of quiescent fluids with different densities. The suspension fluid was stored initially in a lock; instantaneous opening of the lock gate initiated the gravity current that intruded in the middle of the ambient fluid layers. The internal subgrid scale structures of the density current are observed in the simulation. The numerical model has also been applied in the simulation of turbidity current over a mildly inclined surface. The turbidity current was generated by a constant discharge of a well‐sorted sediment and water mixture into the reservoir. The sediment deposition and entrainment near the bottom are considered in the simulation. The vertical velocity profile, turbidity current intrusion speed, and sediment deposition are predicted reasonably well by the numerical model.

Select this Article		Validation of a Coastal and Estuarine Model for Long‐Term Morphodynamic Simulations Driven by Tides, Storms, and River Floods Yan Ding, Keh‐Chia Yeh, Hung‐Kwai Chen, and Sam S. Y. Wang ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)200 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A coastal and estuarine model has been extensively validated by simulating morphodynamic responses to long‐term hydrological conditions including typhoons, storm waves, winds, and river floods occurred in an estuary. The computed morphological changes over several years are in good agreement with the in situ bathymetry measurements. The numerical results also revealed complex flow patterns and morphological changes in the estuary, e.g., bank overflow and coastal inundation, erosion/deposition, as well as breaching of river mouth sand bar. These results are important to understanding of sediment transport and morphodynamic processes in the estuary especially due to storms, tides, and floods. This validated numerical model is, therefore, capable of assisting engineers and researchers to achieve better long‐term coastal flood management and infrastructure design against various complex hydrological conditions in coasts and estuaries.

back to top

COMPUTATIONAL HYDRAULICS AND HYDRODYNAMICS: II (OPEN CHANNEL)

Select this Article		Advanced Guidance on Use of Steady HEC‐RAS Henry H. Hu, M. ASCE and Raymond Walton, M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)201 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract HEC‐RAS is a one‐dimensional steady or unsteady open channel flow model developed by the U.S. Army Corps Engineers' Hydrologic Engineering Center. It is probably the most widely used one‐dimensional program in the world, and is used for a variety of applications, such as flood insurance and flood reduction studies, bridge hydraulics, stream restoration, and dam break analyses. While the HEC‐RAS modeling system is well documented and general guidance on model applications and parameter selections is provided, modelers often do not understand the uncertainty or sensitivity associated with some model parameters. In addition, HEC‐RAS is sometimes misapplied as modelers often do not understand the applicability of HEC‐RAS. This paper presents a series of steady flow model examples to test the sensitivities of three key parameters or processes, including cross section spacing, expansion ratio, and lateral weir discharge coefficient. Using the model test results, practical guidance on model parameterization is provided. In addition, using an example application, cautions of using HEC‐RAS results to interpret a two‐dimensional floodplain are discussed.

Select this Article		Application of the HLL Approximate Riemann Solver to One‐Dimensional Open Channel Flows with Irregular Geometry Xinya Ying and Sam S. Y. Wang ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)202 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Recently, many researchers revealed that the conventional approximate Riemann solvers are inadequate to deal with the real‐life one‐dimensional open channel flows because of problems such as unrealistic flow caused by numerical imbalance as well as inaccuracy in the solution of discharge when the channel has complex geometry and a hydraulic jump is present. To overcome these deficiencies, several new techniques have been proposed, including: (1) adopting the form of the Saint Venant equations which include only one source term representing driving forces; (2) using water surface level as one of the primitive variables; (3) defining discharge at interface and evaluating it according to the flux obtained by the HLL Riemann solver. In this paper, the performance of this new scheme is evaluated by means of two dam‐break flow problems. The comparisons of computed results with analytic solutions and data measured from the physical model show that the scheme is capable of satisfactorily reproducing open channel flows with irregular geometry.

Select this Article		Design Considerations for Confining and Guiding Levees on Alluvial Fans Bruce M. Philips, P.E. and David T. Williams, Ph.D., P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)203 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The dynamic nature of alluvial fans in arid and semi‐arid environments offers numerous floodplain management challenges primarily due to unpredictability of flowpaths and delivery of significant sediment. Construction of levees on alluvial fans is one of the primary structural control measures utilized in historically successful “whole fan” floodplain management that address flood protection requirements. Levee design and hydraulic evaluation for alluvial fans are much different than similar applications for standard riverine locations. Corresponding requirements by FEMA in determining flood hazard definition for alluvial fan locations also complicate the issues. The primary design elements associated with levees which are unique for alluvial fans include (1) geometry and alignment, (2) embankment cross section and (3) armoring requirements. Geomorphic and flooding characteristics on an alluvial fan involve various sources of uncertainties that require the application of statistical procedures to evaluate flooding at a given point on the alluvial fan. Armoring of the levee face is an essential requirement to ensure successful operation and specific analysis must be applied to evaluate the vertical limits of the armoring, specifically toe‐down depths, since scouring of the slope protection is one of the most common failure modes. The hydraulic evaluation must include the analyzes of potential alternative flowpaths, flow‐impingement on the levee, degradation, deposition, sediment ramping, and maximum flooding depths from a variable and random flowpaths. This paper presents the previously described design considerations for the construction of guiding and confining levees on alluvial fans with detailed discussions on each topic.

Select this Article		RSM 3D Turbulent Flow to Improve Sewer Net Instrumentation Jonathan Wertel, José Vazquez, and Robert Mose ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)204 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The aim of this work is the interpolation of a mean flow stream from discreet data supplied by a Doppler velocimeter. This is why a precise flow modeling in needed to be implemented in a code designed for sewer net conduit. A 2D mesh is used to calculate 3D velocity flow. This work deals with the description of a Reynolds stress model for the numerical simulation of uniform 3D turbulent open‐channel flows. The finite volume method is used for the numerical solution (with Matlab) of the flow equations and transport equations of the Reynolds stress components. First the k‐ε model has been implanted to test the method but it is found that both production terms by anisotropy of Reynolds normal stress and by Reynolds shear stress contribute to the generation of secondary currents. The results presented here are the calculation for full section flow in a rectangular channel which is one step in the overall project. Last the velocity profile has been measured in a 20m long experimental channel to validate the code. There is a good agreement between first measurements and the results predicted.

Select this Article		Waller Creek Tunnel Project, Austin, Texas Brian K. Reis, P.E. and William H. Espey, Jr., Ph.D., P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)205 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Since the 1970's, diversion of Waller Creek flood flow has been a goal of the City of Austin to reduce the risk of flooding to businesses downstream of Waterloo Park (15^th Street), thereby encouraging planned development close to the creek and at the street level above. In 1999 the City of Austin selected a joint venture comprised of Espey Consultants, Inc. and Kellogg Brown & Root Services, Inc. (JV) to provide professional services for preliminary design, final design and construction management services for the proposed Waller Creek Flood Diversion Tunnel Project in downtown Austin, Texas. The project includes statistical analyses, hydrologic and hydraulic modeling and optimization, preliminary and final design and economic analyses. The estimated cost of the project exceeds $100 million and will be under construction in the fall of 2010. Construction will be complete in 2014. The project consists of a one‐mile long, 22‐foot diameter bypass tunnel, inlet and outlet structures, and side overflow weir diversion system. The inlet at Waterloo Park will divert approximately 85% of the 5.75 square mile watershed to the outlet at Lady Bird Lake. The side overflow weir system will divert stormwater flow from the lower portion (approximately 15%) of the watershed to the main flood control tunnel. Upon project completion, the 100‐year flood event flow will be contained within the existing creek channel downstream of the inlet structure.

back to top

COMPUTATIONAL HYDRAULICS AND HYDRODYNAMICS: III

Select this Article		Fate Transport of Organic Pollutants in the Coastal Water of United Arab Emirates Walid Elshorbagy ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)206 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Organic pollutants in industrial coastal basins are generated from a number of sources including coastal effluents and loading/unloading offshore stations. Such pollutants may adversely affect the quality intakes of other strategic coastal facilities such as coastal thermal desalination plants. In United Arab Emirates, many of such desalination plants are located along one coast hosting refineries as well as other coastal facilities. Loading and unloading of oil tankers are also practiced from offshore stations. A number of organic pollutants are generated from these sources and can potentially threaten the quality of intake seawater of the nearby desalination plants. This paper presents the results of a fate transport modeling study for two selected organic pollutants; Phenol and PCB‐180 (HeptachloroBiphenyl) in an industrial coastal basin located in United Arab Emirates. A number of parameters involved in the transport processes were determined from lab experiments while most other parameters were estimated from a numerical sensitivity study. The model results depict contour maps of dissolved concentrations of the two considered pollutants for three different wind conditions in summer and winter. The obtained results and observations constitute useful information for the desalination plants' operators due to the effect of intake quality on the quality of final distillate produced from thermal desalination processes.

Select this Article		Three‐Dimensional Modeling of Radionuclide Transport in Inland Waters Aiguo Qian, Jiehui Duan, Ping Ji, and Shuiwei Tan ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)207 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A 3D hydrodynamic model is applied to simulate the radionuclide concentration distribution in typical receiving waters due to discharges from nuclear power plants. For a receiving reservoir, two representative hydrologic conditions are considered to produce water currents, namely, extremely low water level condition and normal water level condition. The boundary condition of the hole‐outflow through the dam is well dealt with in reservoir modeling. The similar hydrologic conditions are also used for modeling the receiving river. Due to the much large river flow, effects of the half‐life decay coefficient on the transport and fate of radionuclide discharge in receiving water are extensively examined. The effectiveness of the 3D model in producing the reservoir current patterns and hence the passive decay mass transport and fate is demonstrated.

Select this Article		Modeling of Wave Driven Circulation and Water Quality in Nearshore Environments Craig Jones, A. M. ASCE and Steve Watt ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)208 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract In order to investigate the effects of nearshore discharges of water quality degrading substances and bacteria in coastal environments, models capable of predicting nearshore circulation due to local wave and tide conditions are required. One of the larger challenges to nearshore coastal modeling is accurately reproducing nearshore circulation due to wave action. Local wave action not only drives circulation through processes such as longshore transport and rip currents, but also contributes significantly to the mixing of water quality constituents. In the present work, a wave model was used to calculate radiation shear stresses and dissipation due to wave action. The shear stresses and dissipation were incorporated into a hydrodynamic model to force circulation in the nearshore environment. The model was applied to a site in Santa Cruz, CA where site specific current data was available. The model reproduces the nearshore current structure observed in the region and was used to study the transport of dredge disposal plumes in the region which could have deleterious effects on local beaches. This presentation will outline the nearshore circulation model development and application.

Select this Article		Use of CFD Modeling for Creating Recreational Opportunities at the Calgary Bow River Weir Fangbiao Lin, Ph.D., P.Eng., Darren Shepherd, P.Eng., Chuck Slack, P.Eng., Scott Shipley, P.E., and Al Nilson, P.Eng. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)209 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The Calgary Bow River Weir Project is intended to remove an existing safety hazard created by an ogee weir, while maintaining the weir's ability to divert water for irrigation and not increasing upstream flood levels. The river reach downstream of the weir will be transformed into a high water channel and a low water channel, each comprised of multiple pool‐and‐drop features to provide recreational opportunities for boaters and improve fish passage at the site. Computational fluid dynamics models were developed to evaluate hydraulic conditions of design modifications to HWC Drop #1. In this study, a volume‐of‐fluid (VOF) model was employed to predict the water surface profile and to assess whether a hydraulic jump would form downstream of the drop structure. The CFD models were validated by comparing CFD results with qualitative and quantitative data collected in the physical models. The comparisons indicated that the CFD models were able to correctly predict hydraulic jump formation immediately downstream of the weir for the existing design, and demonstrated satisfactory hydraulic conditions for the proposed design at flows at which boat passage is expected to occur. This study demonstrated that CFD modeling is a viable tool for predicting flows involving highly deformed water surfaces, such as those associated with hydraulic jumps.

back to top

COMPUTATIONAL HYDRAULICS AND HYDRODYNAMICS: IV

Select this Article		Development of Nutrient Sub‐Modules (NSM) for Integration with USACE Hydraulic and Hydrologic Modeling Systems Billy E. Johnson, Zhonglong Zhang, and Terry K. Gerald ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)210 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The control of nutrients arising form Non‐Point Source Pollution (NPSP) is difficult because the source areas can be hard to identify and typical treatment methods are infeasible due to the distributed nature. While restoration attempts may provide significant returns, they can be costly to implement and often are met with resistance. In order to quantify potential benefits, detailed hydrologic/water quality modeling of watersheds and the effects of Best Management Practices (BMP) is required. Extending model results beyond the range of calibration to model future conditions requires the use of physically based models that include the important processes that generate stream flow, material transport, uptake, loss, transformation, and recycling. In addition, given the complex nature of surface water and groundwater interaction, as well as the spatial nature of nutrient distribution, a distributed source transport model is needed to accurately account for the movement of water and nutrients through the various landscape media where more simplistic models are not applicable, or are homogeneous which is not appropriate for the heterogeneous nature of distributed sources. This paper will discuss the current research efforts and demonstrations taking place at the Engineer Research and Development Center (ERDC) as it relates to the nutrient sub‐modules.

Select this Article		Hydraulic Characteristics of Flow over a Highly Permeable Porous Structure Jan‐Mou Leu, Wei‐Che Huang, and Hsun‐Chuan Chan ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)211 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The present study is carry out to investigate the velocity fields and turbulence characteristics of the flow over permeable structures by channel experiment in low water level. Detailed measurements of the time‐averaged velocity components, turbulence intensity components of permeable and solid structures are taken by the acoustic doppler velocimeter (ADV). The characteristic feature of porous medium is permeable, and the vertical distributions of time‐averaged velocities above permeable structures are more uniform than solid structure due to the slip velocity at the fluid/porous interface. The turbulence intensity above structure with large porosity are slightly greater than small porosity structure, and the permeable structures have smaller turbulence intensity than solid structure around the structures. The results show that the porous medium reduces the turbulence intensity, and then reduce the scour to structures.

Select this Article		Hydraulic Model Calibration on the Coastal Plain: A Case Study in Cameron County, Texas Josha Crowley, P.E. and Alan W. Moore, P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)212 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Development of a representative hydraulic model in flat coastal regions is often problematic. This can be complicated further if the study area is extensively crossed by elevated irrigation canals, roadways or railroad tracks that tend to impede or alter stormwater conveyance. In addition standard hydrologic assumptions, unit hydrograph shapes and hydraulic modeling techniques are often not applicable. This analysis will consider various hydrologic and hydraulic calibration parameters. Hydrologic calibration parameters considered will focus on time of concentration, antecedent moisture condition and peak rate factor. Hydraulic parameters will focus on Manning's “n” value and storage routing. A concern for floodplain managers in this region is that improving the efficiency of the drainage system would reduce storage volumes, thereby increasing peak discharge and causing additional flooding downstream of improvements. The presentation looks at this problem as encountered in the development of a Master Flood Protection Plan for Cameron County Drainage District #5. Drainage District #5 encompasses most of the City of Harlingen, and the Towns of Primera, Combes and Palm Valley. The District drains to the Arroyo Colorado, part of the Rio Grande floodway system and the Gulf Intracoastal Waterway.

back to top

COMPUTATIONAL HYDRAULICS AND HYDRODYNAMICS: V

Select this Article		Flow Simulations for Curb Opening Inlets with Different Longitudinal and Cross Slopes Xing Fang, Ph.D., P.E., Shoudong Jiang, and Shoeb R. Alam ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)213 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Proper highway drainage is essential to ensure safe and comfortable conditions for the road users. The highway pavement and inlet geometry, especially cross slope and longitudinal slope and local depression and transition length, usually determine the highway surface drainage capacity. In this study, FLOW‐3D is utilized to model the unsteady free‐surface flow through curb opening inlets with different longitudinal and cross slopes. FLOW‐3D, developed by the Flow Science, Inc., is a three‐dimensional computational fluid dynamics software that can be utilized as “Virtual Lab” to study complex flow problems. FLOW‐3D utilizes a true volume of fluid method (TruVOF) to compute free surface motion and the fractional area/volume obstacle representation (FAVOR) technique to model complex geometric regions. Flow characteristics near curb opening inlets are carefully examined. Inlet efficiency is determined from flow simulation results for the inlets with various longitudinal and cross slopes, especially for small slopes where laboratory tests were not able to be conducted. Inlet efficiencies for curb opening inlets with different transitional lengths before and after the inlet are examined using FLOW‐3D simulation models. Simulation results are compared with laboratory observations with good agreement.

Select this Article		Integrated Surface Water and Groundwater Modeling to Study Water Level Fluctuations of Isolated Lakes in Florida E. Zia Hosseinipour, Yuan Li, and Hamid Bojd ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)214 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract This paper discusses the results of an integrated hydrologic modelling to study potential adjustment to the established minimum flow and levels for lakes in Northwest Hillsborough County, Florida. The northwest area of Hillsborough County is characterized by numerous lakes and wetlands many of which are interconnected and managed via control structures or groundwater augmentations. Some lakes in the area are isolated and have much smaller contributing watershed and rarely reach their established minimum water levels. It is surmised that as a result of drainage alteration and land development some of these lakes are more impacted than others. In 2004–2005, challenges were made to the application of Southwest Florida Water Management District's Minimum Flow and Level rule (MFL) for Category 3 lakes (Raleigh, Rogers, and Starvation) and have, to some degree, raised the same issues related to land use/drainage alterations and lake water level impacts. The primary purpose of this study was to examine whether the drainage alteration and land development within the area have significantly affected the natural flow into the subject lakes, and determine whether such alterations warrant adjustment of the proposed lake minimum levels. To this end, an integrated surface and ground water model of the basin using the MIKE SHE software was developed to look into the inter‐relationships among surface and ground water, water supply pumping in the adjacent well fields and drainage alterations in the past several decades. The study was conducted in three phases. Phase I consisted of data collection and digital terrain model (DTM) development for the proposed study area. During phase two, a complete watershed evaluation was performed, including hydrologic and hydraulic features inventory, surface water/subsurface water assessment, as well as a preliminary integrated modeling plan and approach. In phase III, the subject of this paper, an integrated hydrologic model of the site was developed to assist in the development of watershed management plan, with emphasis on the assessment of the potential impacts on lake water levels resulting from human activities such as drainage alteration and land development. To study the impacts, the calibrated model was used to simulate both the existing condition and historic landuses to compare water levels and develop strategies to lessen the impacts on the lake water levels.

Select this Article		Laboratory Investigations on Development of Energy Dissipators for Square Shaped Outlets Arun Goel ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)215 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The paper examines the effectiveness of prevalent USBR type VI models and proposes new shorter and efficient designs by means of laboratory experimentation. The models are tested on 4cm×4cm square opening (d = 4cm) with an erodible material and a constant run time for inflow Froude no Fr = 6.83 with a diverging side walls at a slope of 1 V:0.75 H up to a length of 3.5d. A non‐dimensional number called as performance number has been used as for comparison of performance of the models. Several appurtenances various shapes and sizes like splitter block, impact wall, intermediate sill, and end sills are tested in the laboratory. It has been found that this special pentagonal shaped block quite is helpful in spreading the jet of water in a shorter length, resulting into better and more energy dissipation. It was found that the length of energy dissipator models can be reduced by more than 15% as compared to USBR impact type VI energy dissipator model without sacrificing the performance.

Select this Article		Optimization of a Clearwell Design by Using a 3D CFD Model Liaqat A. Khan and Edward A. Wicklein ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)216 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A practical application of a three‐dimensional (3D) computational fluid dynamics (CFD) model to optimize the design of a storage reservoir for its use as a clearwell is presented in this paper. A computational grid of the 20 million gallon (MG) reservoir, incorporating 285 columns supporting the roof, was created from existing design drawings. Initial model simulations indicated poor mixing and contact time, with T₁₀/T ratio of about 0.2, where T₁₀ is the tenth percentile of the hydraulic residence time, T. Therefore, various baffle arrangements were investigated to increase the T₁₀/T ratio to 0.72 and minimize the cost associated with retrofitting the reservoir with baffles. These duel considerations resulted in an unconventional design of the clearwell with an estimated cost saving of 45 percent. The paper analyzes the computed circulation patterns to identify the causes of significantly different hydraulic and mass transport characteristics of the reservoir, with and without columns, and the proposed design incorporating baffles.

Select this Article		Turbulence Characteristics of Flow in a Spiral Corrugated Culvert Fitted with Sloped‐ and Slotted‐Weir Baffles Ryan R. Morrison, Rollin H. Hotchkiss, Mark Stone, David Thurman, and Alex R. Horner‐Devine ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)217 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Baffles are often used to retrofit culverts to aid in fish passage. The objective of this experimental investigation was to compare the turbulent flow structure inside a full‐scale spiral corrugated culvert fitted with sloped‐ and slotted‐weir baffles to available turbulence descriptions for non‐baffled culverts. Velocity measurements were taken in a 1.83 m diameter, 12.2 m long corrugated metal culvert fitted with sloped‐ and slotted‐weir baffles using a Sontek Micro‐acoustic Doppler velocimeter for flow rates of 0.043, 0.085, 0.113, and 0.198 m³/s and culvert slopes of 1.14, 3.00, and 4.33%. Results showed there were only minor differences in the turbulent flow structure created by each baffle type. The most significant differences included higher lateral turbulent intensities on the edges of the jet created by the slotted‐weir baffles, and higher turbulent kinetic energies on the left side of the culvert (looking downstream) caused by the sloped‐weir baffles. Downstream from a slotted‐weir baffle, a reduced velocity and streamwise turbulent intensity zone was found near the left edge of the flow that was similar to that found in the bare culvert. The sloped‐weir baffles produced a less pronounced zone near the right edge of the flow.

back to top

COMPUTATIONAL HYDRAULICS AND HYDRODYNAMICS: VI (NUMERICAL MODELING)

Select this Article		2D Smooth Mesh Generation in Complex Geometries Yaoxin Zhang, Yafei Jia, and Sam S. Y. Wang ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)218 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Quality mesh generation for complex computational geometries still remains a challenging step in Computational Fluids Dynamics (CFD) analysis. This paper presents a method for 2D smooth mesh generation in geometrically complex domains where the local orthogonal conditions may result in skewed or overlapping mesh which is generally acceptable in numerical simulation. In the proposed method, two exponential parameters are introduced into the RL (Ryskin and Leal) orthogonal mesh generation system to control the distortion functions (orthogonal conditions). These parameters are adjustable and can be either user‐specified or automatically evaluated by the smoothness conditions. With the relaxed orthogonal conditions, nearly orthogonal but smooth mesh is achieved in complex geometries. Examples and applications are also investigated in this paper.

Select this Article		A Characteristics‐Based Finite Element Method for Simulating Two‐Dimensional Overland Flow Problems Gour‐Tsyh Yeh and Guobiao Huang ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)219 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The method of characteristics (MOC) in the context of finite element method was applied to simulate two‐dimensional (2D) shallow water equations for overland flows. Many researchers have pointed out the advantage of MOC in solving two‐dimensional shallow water hyperbolic equations having wave‐like solutions. At the same time, they considered MOC for two‐dimensional overland flow being non‐tractable on complex topography and boundaries. For two‐dimensional overland flows, finite element methods are very flexible in dealing with complex boundaries. The intrinsic difficulty in implementing MOC for 2D overland flows is that there are infinite numbers of wave characteristics in 2D problems, although only two independent wave directions are needed for a well‐posed solution to the characteristic equations. We have implemented a numerical scheme that attempts to diagonalize the characteristic equations based on pressure and velocity gradient relationship. This diagonalization scheme was evaluated by comparison with other choice of wave characteristic directions in the literature. The circular dam break problem was solved with different selections of wave characteristic directions and the performance of each selection was evaluated based on accuracy and numerical stability. Finally, a 2D overland flow problem over complex topography in a wetland setting with very mild slope was solved with the diagonalization scheme along with other wave‐selection directions to demonstrate its applicability.

Select this Article		Modeling Propagation of Long Wave Run‐Up along Sloping Boundaries Burak Turan and Keh‐Han Wang ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)220 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Development of two‐dimensional (2D) hydrodynamic model to simulate the propagation of long waves in a domain with sloping boundaries is presented in this paper. This study adopts the finite‐volume method to solve hyperbolic shallow water equations and model various wave run‐up problems. Godunov type HLL approximate Riemann solver is combined with divergence form of the bed slope to be able to simulate waves on irregular topography. The surface gradient method is used to have a well balanced scheme that the numerical errors can be removed. The accuracy is second order in space and time. The computational domain is constructed with unstructured triangular cells. The developed model, which is capable of simulating flow over dry and irregular domain, is run for dam break wave over a sloped bottom, tidal wave onto a sloped beach and solitary wave around a conical island. The experimental and numerical results published are used to verify the stability and accuracy of the model.

Select this Article		On the Mass Conservation of the Four‐Point Implicit Scheme Li Chen and Mark C. Stone ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)221 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The four‐point implicit scheme has long been applied in hydraulic modeling to solve the one‐dimensional Saint Venant equations. Because of the advantages of numerical stability and efficiency, it has become the most widely adopted scheme for the simulation of unsteady open channel flows. In this paper, the scheme is re‐analyzed using the viewpoint of the finite volume method. It is found that the mass conservation is defected at the inflow boundary if the parameter θ is chosen not equal to 0.5. The reason for this error is that the input flow in the model is discretized using the parameter θ and is different from the expected value. However, in practical applications θ > 0.5 is always used to maintain the unconditional numerical stability. Therefore the mass imbalance at boundaries introduces error to most cases. The error can be introduced either from the upstream boundary or from lateral inflow boundaries. The effect of this error is not serious when the modeling time step is very small or the inflow changes very slowly with time, which are generally not satisfied for actual highly unsteady flow simulations. Potential solutions for this issue are investigated and it is found that the only sound approach is to modify the scheme at the boundary.

back to top

ECO HYDRAULICS/ECO HYDROLOGY: I

Select this Article		Analysis on Spawning Site of Chinese Carps in the Reservoir of Three Gorges Project Based on the 1‐D Hydrodynamic Model Li Chong, Liao Wengen, Chen Daqing, Xu Tainbao, Liu Shaoping, and Liu Jianhu ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)222 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The hydrodynamic variation process of the river flow in the reservoir of the Three Gorges Project was simulated by using the software Mike 11 based on the hydrological observation data from 2002 to 2003. According to the growth status of spawns or fries captured at the Yunyang Gauge Station, Chongqing city, the spawning sites of different kinds of Chinese carps can be determined by the flow distance based on the hydrodynamic calculation results. The accuracy of the spawning sites determined by this method is much better than those calculated according to the averaged velocity of the river. The uncertainty of this method is also discussed.

Select this Article		Effectiveness of Artificial Substrate in Capturing and Retaining Sturgeon Eggs Amanda L. Cox, Christopher I. Thornton, and Karl W. Eriksen ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)223 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Over the past 50 years, there has been a well‐documented collapse in white sturgeon recruitment in the Kootenai River, and white sturgeon has been listed as an endangered species since 1994. Libby Dam, constructed along the Kootenai River in northwest Montana, started operation in 1974, which is believed to be the last successful year for white sturgeon recruitment. Lack of appropriate spawning substrate is thought to be a primary factor responsible for white sturgeon population recruitment failure. White sturgeon are broadcast spawners that release adhesive, negatively buoyant eggs that sink to the riverbed. Three‐ to six‐foot sand waves (or dunes) now exist in the reach where spawning occurs. Available information suggests that suffocation and high egg mortality occur where the bed is composed of shifting sand substrate. A Substrate Enhancement Pilot Project Implementation Plan was developed by the Seattle District, U.S. Army Corps of Engineers, to test the effectiveness of various types of artificial substrate for improving spawning success in the reach downstream of Libby Dam. 1:20 Froude‐scale physical modeling of different artificial substrate designs was conducted at the Colorado State University Hydraulics Laboratory. This investigation involved three separate tests of rock riprap placed as a mass on the riverbed that projected above the effects of the sand waves. This paper presents an analysis of the flow velocities and turbulent Reynolds stresses that developed over the surface of each artificial substrate. In addition, an evaluation of the effectiveness of each substrate to trap and retain sturgeon eggs is presented.

Select this Article		Food Web Models for Stream Ecosystems Omar I. Abdul‐Aziz, Bruce N. Wilson, and John S. Gulliver ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)224 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Ecohydrological modeling of food webs can be a useful tool in stream/river health assessment, restoration, and management by providing insight into the long‐term dynamics of biota. Conventional food web models are mostly limited to lake or marine ecosystems. In contrast to these models, stream ecosystem models need to capture the response associated with shorter residence times as well as the impacts of natural (hydrology, geomorphology, etc.) and anthropogenic (building dams and reservoirs, industrial pollution, etc.) drivers. Further, the benthic and non‐benthic zones of streams/rivers have different physical, chemical and biological compositions. To investigate hydrologic drivers, along with other environmental and geomorphologic constraints, dimensional and non‐dimensional food web models have been developed to evaluate ecosystem dynamics of the benthic and non‐benthic zones of streams and rivers. Insights gained from these applications can be used to critique different food web modeling approaches and recommend an appropriate model for a given stream ecosystem.

Select this Article		Strategies for Cutting Management of Riparian Vegetation J. M. Leu, H. C. Chan, Yafei Jia, Suiliang Huang, and Sam S. Y. Wang ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)225 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract This study presents the numerical predictions on the detailed hydrodynamic and habitat quality characteristics of riparian vegetation by using a depth‐averaged two‐dimensional flow model. The model solves the depth‐averaged Reynolds Averaged Navier‐Stokes Equation. The vegetative effect is considered by a drag force exerted by the flow on the vegetation, resulting in extra source terms included in the momentum equations. Simulated results of flows in a rectangular and a compound channel with vegetation along one side are coincided with the previous experimental data. Furthermore, the model is used to simulate the cutting management of riparian vegetation. Five different scenarios are proposed in this study, including original, as well as cutting along main‐channel side, cutting along bank side, alternative cutting and reducing vegetative density. The influence of the proposed scenarios on hydrodynamic behaviors is investigated in a rectangular channel. Simulated results suggest that cutting along the main‐channel side is the most effectively scenario among others in reducing the water depths and flow velocities of the original one.

back to top

ECO HYDRAULICS/ECO HYDROLOGY: II (HABITAT)

Select this Article		Case Study of Impacts of Highway Culverts on Salmon and Steelhead Kamal Sah, P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)226 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The salmonids, salmon and trout, are economically and socially important fishes that require consideration and protection when roads are constructed and maintained within their ranges. Over the courses of their lives both resident and anadromous salmonids require a variety of aquatic habitats. It is well established that that these fishes need to have efficient access among streams in addition to efficient access to different habitats within streams to maintain viable populations. Barriers may either physically block movement or impose excessive energy costs on movement, thereby preventing or seriously impeding access to necessary habitats and affecting population sizes. Insuring fish passage at highway stream crossings is a key component of salmonid conservation and restoration efforts. Thus, the identification, prioritization, and treatment of migration barriers is a vital step towards recovering salmonid populations by restoring ecological connectivity.

Select this Article		The Use of Physical Modeling to Design Kootenai River White Sturgeon Spawning Habitat Karl Eriksen, Alan Coburn, Amanda Cox, and Chris Thornton ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)227 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Kootenai River White Sturgeon has become endangered because of its inability to successfully spawn. The sandy riverbed where the sturgeon currently spawn is considered an unsuitable spawning habitat. Successful sturgeon spawning locations in the Columbia and Snake rivers have cobble and boulder bed material. The Seattle District, U.S. Army Corps of Engineers has supported a series of physical model studies conducted by Colorado State University to evaluate artificial rock habitat structures that could be built in the Kootenai River to improve sturgeon spawning conditions. The study has focused on what type of structure would provide suitable spawning habitat and be sustainable in the sandy river environment. The three phase study has evaluated alternative sizes shapes, materials, spawning performance and sustainability.

back to top

ECO HYDRAULICS/ECO HYDROLOGY: III (SEDIMENTATION)

Select this Article		Evaluation of Flow and Sediment Models for the Rillito River Jennifer G. Duan, Anu Acharya, Mary Yaeger, and Shiyan Zhang ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)228 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Hydrodynamic and sediment transport models are useful engineering tools for predicting flood flow. Many models such as HEC‐RAS, HEC‐6, IALLUVIAL, SRH‐1D were developed for perennial rivers, and may not be suitable to ephemeral rivers in arid and semi‐arid regions. This paper outlines a comparison study that examined the water surface and bed elevations of a flood event exceeding 100‐year flood in the Rillito River at Tucson, Arizona. The result of IALLUVIAL2, HEC‐RAS and GSTAR1D models were compared with field survey data. Results showed that IALLUVIAL2, which cannot compute bridge effects, predicted a flood similar to that of the more commonly used HEC‐RAS model, which take bridges into account. Both models underestimated the flooding by about 2 to 4 feet, but accurately predicted the progression of each flood flow. This study also found the most appropriate sediment transport and roughness equations for this particular river are Laursen sediment equation and Manning's relation. The results indicated the need of an appropriate model for predicting flood flows in ephemeral streams for water resource managers, engineers, and urban planners.

Select this Article		Numerical Simulation of Density Current in Chicago River Using Environmental Fluid Dynamics Code (EFDC) Xiaofeng Liu and Marcelo H. Garcia ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)229 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The Chicago Waterways System (CWS) is very complex and a complete understanding of the flow and water quality phenomena is not possible with current modeling tools. Among many interesting aspects, bi‐directional flows have been observed in the Main Branch of Chicago River (MBCR) during winter time. Instead of flowing downstream into the South Branch (SB), part of the water from North Branch (NB), which usually carries runoff from a 100 square mile watershed and treated municipal sewage effluent released by the North Side Water Reclamation Plan (WRP), might flows into MBCR. This will have a huge impact on the water quality in MBCR, where the downtown Chicago is located. Physical model and field measurements of the CWS have been done to investigate the possible cause. Through these previous studies, density current has been identified as one of the main cause. A preliminary three dimensional numerical model also has been used in University of Illinois at Urbana and Champaign (UIUC) to simulate the density current. Although the bi‐directional flow phenomena have been reproduced in the 3D model, the flow conditions are simplified and only very short period of time is simulated. In this paper, a three‐dimensional environmental fluid dynamics code (EFDC) is used to simulate the flow in the Chicago River system (including NB, SB, and MBCR). EFDC is a public domain code which is supported by the Environmental Protection Agency (EPA) and has been widely used in many rivers and estuaries. It uses stretched or sigma vertical coordinate and Cartesian or curvilinear, orthogonal horizontal coordinate. Three‐dimensional, hydrostatic, free surface, and turbulent flow equations are solved. Water quality models (such as sediment, temperature, toxics, dissolved oxygen, and biological oxygen demand) are also implemented. For this paper, the EFDC code is modified to simulate only the density current in CWS mainly due to the dissolved particles. The tests cases used in this paper are from the physical model work done in the hydrosystems lab in UIUC. The numerical model is validated and tested against the experiments. Good results have been achieved. More numerical simulations will be done to expand the parameter space. Water quality models will be activated in the future to see the environmental impact of different management strategies.

Select this Article		Scour and Riprap Protection in a Bottomless Arch Culvert B. M. Crookston, S. M. ASCE and B. P. Tullis, M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)230 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Bottomless arch culverts are employed as ecological passageways at road crossings. Such culverts are commonly used for fish passage as the adjacent natural channel reaches can be simulated and habitat barriers minimized (i.e. high base flow velocities, perched culvert outlets, etc). Though they have been developed to be environmentally sensitive, there is limited understanding of the hydraulic characteristics of bottomless arch culverts. To provide some design guidance specific to streambed stability in culverts, a streambed stability study was conducted using a smooth walled, 0.61‐m (2‐ft) diameter circular bottomless arch culvert and featured four different streambed armoring materials with the d₅₀ ranging in size from 6.75‐mm to 37.3‐mm. Several culvert entrance configurations were tested with headwater depths ranging from unsubmerged to submerged inlet conditions. Experimental data were used to evaluate eight published riprap stone‐sizing stability relationships for potential applicability to streambed stability design in bottomless arch culverts.

Select this Article		Sediment Sorting around Experimental Spur Dike Jennifer G. Duan, Anu Acharya, and Mary Yeager ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)231 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract An experiment was conducted in a laboratory flume at the St. Anthony Falls Laboratory, University of Minnesota, to study the sorting of mixed grain sized sediments around a spur dike in a flat‐bed open channel. The flow field was measured by using a micro‐acoustic Doppler velocimeter (ADV). Time histories for velocities in all three spatial directions were recorded at the upstream and downstream cross sections near the dike. Results showed that two counter‐rotating, secondary flow cells originated at the dike: one cell resided in the recirculation zone and grew gradually toward downstream, and the other remained in the contracted primary flow zone, decaying as it transported downstream. These measurements illustrated spatial distributions of time‐averaged velocity, turbulent Reynolds stresses, and mean and turbulent kinetic energy at the neighborhood around the dike. During sediment experiments, 15cm‐thick well‐sorted sediment mixture was placed on channel bed. A constant flow was discharged at the upstream until a scour hole was fully developed near the dike. Sediment size distribution at the scour hole showed sediment sorting closely related to turbulent flow field around the dike. The sorting of sediment mixture primarily attributed to the turbulent Reynolds stress, which is three times as large as the mean shear stress of incoming flow. For uniformly sized material, the scouring hole will evolve to a maximum depth until the Reynolds stresses are smaller than the critical shear stresses of a single grain‐sized material. In the case of non‐uniform material, the surface of scour hole was armored with sediment coarser than the substrate material, so that the scour hole will not be as deep as the one formed in a mobile bed of uniform bed material.

back to top

ECO HYDRAULICS/ECO HYDROLOGY: IV (FISH PASSAGE)

Select this Article		Culvert Retrofit and Fish Passage: At Odds? Joseph R. Webb and Rollin H. Hotchkiss ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)232 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Culverts throughout the country are approaching or are past their original design lives. These ‘baby boomer’ culverts will need to be repaired, rehabilitated, or replaced. Because entire culvert replacement is so expensive and intrusive, alternate measures to extend the culvert project life are growing increasingly popular. One such method is slip lining, where a ‘sleeve’ is installed within an existing culvert barrel and stabilized. Plastic pipe sleeves are very popular for slip lining primarily because the plastic material's lower Manning's roughness value allows for the culvert capacity to be maintained despite a reduction in culvert size. Unfortunately, the reduced friction within the barrel can create a barrier to fish passage due to increased water velocities. The increased velocities also cause greater outlet scour which can result in further obstacles to fish passage. These new fish barriers can greatly affect aquatic ecosystems by limiting the access that fish have to smaller tributaries used for spawning and rearing—access that is critical to the life‐cycles of many fish. It is suggested that mitigation of the increased velocities should go hand‐in‐hand with slip lined culvert design projects where fish passage (present or future) is to be considered. Can the demand for hydraulic capacity as well as the demand for fish passage be satisfied? To this point, there has been very limited experience in providing for fish passage through slip lined culverts. Research and reviews of current methods, as well as development of new design methods are still in progress.

Select this Article		Lessons from Fish Passage Waterways in Oregon and Factors for Improving their Construction Sheryle Quinn, Hamid Moradkhani, David Sillars, and Trevor Smith ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)233 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Stream enhancement in Oregon is primarily focused on improving fish passage conditions. Oregon state law requires that hydraulic structures located in water properly provide fish passage. Increasingly stringent state and federal require fish passage designers to become more cognizant of hydraulic conditions over a range of flows to avoid expensive structural failure of hydraulic structures. These hydraulic structures may include culverts, bridges or roughened channels. Roughened channels are man‐made stream channels utilized for retrofitting a hydraulic structure for fish passage when an existing hydraulic structure is structurally sound but deemed inadequate for fish movement through the passage. A variety of methods are utilized for the design of fish passages such as no impedance, geomorphic simulation, hydraulic simulation and hydraulic design. Mixtures of materials are used to construct the bed of roughened channels from fines such as sand, silt and gravel to coarse elements like cobble and boulders. Fines are a critical element in limiting permeability of the constructed bed thus keeping stream flow concentrated in the roughened channel during low flow periods. Our study focuses on the tendency for structural failure in roughened channels. The study goals are to determine the significant hydraulic design factors affecting the success or failure of roughened channels, particularly the loss of fines from the channel structure by examining actual fish passages in the region. Improving fish passages to enhance fish movement through the passage is a priority for government agencies such as Oregon Department of Transportation (ODOT) and Oregon Transportation Research and Education Consortium (OTREC) who have to use less funding more effectively.

Select this Article		Modification of River Hydraulics by the Invasive Diatom Didymosphenia geminata Aaron I. Packman, Scott Larned, David Plew, and Kay Vopel ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)234 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The diatom Didymosphenia geminata (“Didymo”) forms thick and dense mats under low‐nutrient and high‐shear conditions. To investigate the effects of Didymo on open‐channel hydraulics, we collected cobbles covered with Didymo mats from the Waitaki River, Canterbury, New Zealand. The cobbles were then emplaced in a recirculating flume and the system hydraulics were observed under several imposed flow rates. Following these measurements, the Didymo mats were removed from the cobbles, and the measurements were repeated over the bare cobbles. The mats overlapped and bridged gaps between cobbles, and thus were expected to reduce form drag. However, shear velocities and friction factors increased when Didymo mats were present, indicating that Didymo‐covered beds are hydraulically rougher than the cobble beds despite the fact that the cobble surface is smoothed by the presence of the mats. We conclude that the mats introduce an additional roughness scale, and that their surface is much rougher than the bare stones. This conclusion is supported by direct visual observations of the mat morphology.

back to top

ECO HYDRAULICS/ECO HYDROLOGY: V

Select this Article		Development of a Multi‐Beneficial Surface Bypass Alternative for Juvenile Fish Passage at McNary Dam Ken E. Hansen, Rick E. Long, and Kevin D. Nielsen ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)235 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract As part of a comprehensive program to enhance juvenile fish passage at McNary Lock and Dam to improve the survival of downstream migrating juvenile salmonids, the Walla Walla District is performing an investigation to develop benefits and costs for different alternatives for a permanent installation of a surface passage route at McNary Dam on the Columbia River. The desirable result will be development of a permanent installation that provides the greatest opportunity for improving downstream migration with fewer impacts on power generation, total dissolved gas levels, upstream migrants, navigation system, and the ability to pass flood flows. The surface bypass technology being implemented on the lower Snake River projects is to draw water from the surface using an elevated spillway crest located in a spillway bay. Utilizing a conventional spillway bay has inherit problems of using a spillway and stilling basin that were designed for efficiently passing a high volume of water and dissipating the associated energy. A promising alternative is a centerdam surface bypass (CSB) concept that utilizes an existing non‐overflow section of the dam located between the powerhouse and the spillway. The purpose of this paper is to present the opportunities and benefits from developing a flume specific for fish passage that also has the potential of improving the overall objectives for operating McNary Dam. The primary, unique feature is to supply water under the high flow jet that is moving at a high velocity as it enters the tailrace. The feature almost eliminates the undesirable flow entrainment, high‐shear zone, and re‐circulating eddies in the tailrace that is typical of a high flow bypass.

Select this Article		Physical Habitat Model for the Rio Grande Silvery Minnow Mark C. Stone ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)236 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The Rio Grande Silvery Minnow (RGSM) is an endangered species found in the Middle Rio Grande River in New Mexico. RGSM were historically abundant throughout the Rio Grande Basin, but now only occur downstream of Cochiti Dam to the tailwater of Elephant Butte Reservoir (designated as critical habitat). The decline of this species is primarily attributed to hydrologic manipulations caused by extensive diversions and impoundments. Further habitat degradation has resulted from stream channelization, loss of floodplain connectivity, invasive species, and watershed and riparian degradation. The primary objective of this study was to develop a habitat evaluation model driven by a two‐dimensional hydrodynamic model and to apply the model to the Rio Grande Silvery Minnow in order to evaluate habitat suitability under unsteady flow conditions. An emphasis was placed on the availability and fragmentation of overbank habitats. The model results revealed high variability in habitat abundance and patchiness as a function of streamflow. Also, the quantity and connectivity of habitat was substantially different during the rising limb of an unsteady hydrograph when compared with the receding limb. The results demonstrate that this modeling technique provides valuable information for evaluating RGSM habitat and for targeting restoration sites on the Middle Rio Grande.

Select this Article		Three‐Dimensional Coastal Thermal Recirculation Modeling: A Case Study Yonas Kinfu, Kit‐Yin Ng, and Yifan Zheng ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)237 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A 3‐D hydrodynamic and heat transport computer modeling study was conducted in support of the intake and outfall design of a once‐through circulating water system for a new 4×350 MW thermal power plant located on the coast of ∗∗∗∗, Libya. Thermal recirculation at the proposed intake due to the new and existing discharges was examined with the 3‐D model developed using the modeling software Delft3D‐FLOW. The thermal impact of the proposed discharge on the intake of an existing power plant was also assessed. The site‐specific 3‐D hydrodynamic and heat transport model was developed and calibrated using field measurements of currents, water levels and temperatures. Proposed discharge and intake design locations were tested and found to satisfy the maximum water temperature increase criteria.

Select this Article		Using Two Dimensional Hydraulic Models for Restoration of Upper Columbia Basin Streams Cassie C. Klumpp ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)238 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The use of two‐dimensional hydraulic models for assistance in understanding of Upper Columbia Basin Streams was applied on the Upper Methow River located in Washington State. The Upper Columbia Spring Chinook Salmon, Steelhead and Bull Trout Recovery Plan (UCSRB, 2007) identified potential restoration strategies for basins in the upper Columbia. The UCSRB recovery plan recommended additional research to identify locations for preservation and restoration and also recommended additional examination of fluvial geomorphic processes to assess how processes affect habitat creation and loss. Identifying fluvial processes for existing and future conditions was applied to understand channel complexity for side channel and floodplain connectivity and for in‐channel habitat. The SRH‐2D (Sediment and River Hydraulics Two‐dimensional) model was applied to a reach in the Upper Methow to determine existing and future channel processes. Application of the model enhanced understanding of channel processes and floodplain and side channel connectivity to help identify potential restoration and preservation projects. The model was able to provide quantitative results for bankfull and higher flows that provide indicators of channel and floodplain function, particularly when combined with geomorphic mapping and biological analysis from a multi‐disciplined technical team.

back to top

HYDRAULIC STRUCTURES: I

Select this Article		A Multidimensional Anisotropic Two‐Phase Flow Model to Predict Total Dissolved Gas in Wanapum Dam Marcela S. Politano, Pablo Carrica, and Larry Weber ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)239 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A two phase model based on mechanistic principles capable of predicting water entrainment, gas volume fraction, bubble size and total dissolved gas (TDG) concentration in hydropower installations is presented. The model uses a Reynolds stress model accounting for the attenuation of the normal fluctuations at the free surface to capture the anisotropic turbulence structure and water entrainment observed in the spillway surface jets. A modified bubble‐induced turbulence term is extended for the Reynolds stress components to account for suppression and production of turbulence by the bubbles. A bubble number density transport equation is used to predict the bubble size, which can change due to mass transfer and pressure. The TDG is calculated with a two‐phase transport equation in which the source is the bubble/liquid mass transfer, function of the gas volume fraction and bubble size. Quantitative agreement between predictions and field data for the TDG and velocities in the stilling basin of Wanapum Dam is obtained. Numerical results of the hydrodynamics and TDG for two different operational conditions are presented discussed.

Select this Article		Froude Similitude and Scale Effects Affecting Air Entrainment in Hydraulic Jumps Hubert Chanson and Frédéric Murzyn ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)240 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A hydraulic jump is the rapid transition from a high‐velocity to a low‐velocity open channel flow. It is characterized by strong turbulence and air bubble entrainment. Detailed air‐water flow properties were measured in hydraulic jumps with partially‐developed inflow conditions. The present data set together with the earlier data of Chanson (2006) yielded similar experiments conducted with identical inflow Froude numbers but Reynolds numbers between 24,000 and 98,000. The comparative results showed some drastic scale effects in the smaller hydraulic jumps in terms of void fraction and bubble count rate distributions. The present comparative analysis demonstrated quantitatively that dynamic similarity of two‐phase flows in hydraulic jumps cannot be achieved with a Froude similitude. In experimental facilities with Reynolds numbers up to 10⁵, some viscous scale effects were observed in terms of the rate of entrained air and air‐water interfacial area.

Select this Article		Side‐Channel Spillway Hydraulics (Case Study: Lake Skinner Spillway Adequacy Evaluation) D. W. Baker, P.E., M. ASCE and K. A. Reedy, P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)241 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The hydraulics of side‐channel spillways can be complex due to numerous potential flow regimes at the varying flow rates, energy losses from a wide variety of physical conditions, and the complexities associated with spatially varied flow with increasing discharge within the side channel. The analysis can become even more complex in the event that water levels in the side‐channel begin to cause tailwater impacts or full submergence of the upstream spillway. Lake Skinner is owned and operated by the Metropolitan Water District of Southern California (Metropolitan) and this existing dam spillway utilizes a unique side‐channel configuration that includes all of the above mentioned complexities. When originally designed in the 1960s, a reduced scale physical model of the ultimate spillway configuration was constructed and utilized along with mathematical computer models to predict how the spillway would operate under various flow conditions. Since the dam was constructed 40 years ago, the upstream watershed has realized changes in land use resulting in potential changes to the drainage basin runoff characteristics. In 2006, Metropolitan began to investigate if these changes to the drainage basin could affect the adequacy of the Lake Skinner dam spillway and retained Black & Veatch hydraulic engineers and hydrologists to perform the evaluation. Although the reduced scale physical model and mathematical computer model from the original design where not available, reports documenting the past findings were located. Utilizing the documented characteristics of the spillway as calibration data, modern day computer tools were utilized to construct a computer model of the complex spillway system. The computer modeling included the use of the Hinds side‐channel spillway equation, the U.S. Army Corps of Engineers HEC‐RAS and HEC‐HMS modeling tools, and ogee spillway evaluations procedures from the U.S. Bureau of Reclamation's Design of Small Dams (1987). A Visual Basic Program integrated with an Excel Spreadsheet was developed to link the input and output variables of the various modeling packages and to perform logical iterations as required to converge on realistic results.

back to top

HYDRAULIC STRUCTURES: II

Select this Article		Am I Underestimating or Overestimating My Dam Freeboard Design? Carmen E. Bernedo, P.E., M. ASCE, Lori L. Hadley, and John C. Haapala, P.E., M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)242 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Recent activities in the design of reservoirs in coastal regions have pointed out the challenges of applying coastal engineering to inland reservoirs. And the impact of the interpretation of alternative methods can be MAJOR! Analysis on one project showed a cost impact on the order of $20 million using the same basic wind and rainfall design criteria, but alternative methodologies. How can that be? It is easier to understand when the design is for shallow reservoirs with large surface areas and long impoundment perimeters. One reservoir covered a surface area of 17,000 acres with a fully encircling embankment dam 20+ miles in length. In south Florida, subject to powerful hurricanes, embankment freeboard is a major cost component of any dam. The complex nature of coastal hydraulics has historically been evaluated using such tools as the Shore Protection Manual (SPM), Coastal Engineering Manual (CEM), and numerical wave models such as STWAVE. Due to the importance of freeboard design, a detailed effort was made to compare the alternative methodologies. Wave heights were determined using equations (CEM/SPM) and modeling (STWAVE). Wave runup and overwash were evaluated using numerical methods from the SPM, CEM, Technical Advisory Committee on Flood Defense (TACFD) guidance, and the computer program ACES. Wave heights, runup, and overwash can be determined using different sources in series, but not always with the consistency necessary for accurate results. When terminology and formulas become mixed between different references, a thorough understanding of the fundamental principals and formulas is essential. This paper will emphasize understanding the basis of the formula or methodology for correct application. Numerical results are presented in comparative tables as well as recommendations. This paper should be of interest to all those involved in the design, review, or re‐evaluation of freeboard for dams.

Select this Article		Application of a Mitered Ogee Crest to Steep Stair‐Stepped Spillways W. H. Goodridge, W. J. Rahmeyer, M. ASCE, M. A. Morrison, P.E., and Paul Costa, P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)243 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Design flow requirements for both new and existing dams have increased over the past 30 years due (in part) to a series of dam failures caused by embankment overtopping. Increased spillway design flow requirements often require the renovation and re‐design of the spillway crest for increased discharge without increasing reservoir pool elevation. Mitered ogee crests can be a viable alternative to the use of traditional ogee crests and to replacing broad crested weirs for increasing the discharge capacity of an existing spillway. Although the use of a traditional ogee crest would be the optimum design for increasing discharge, the use of a mitered crest would be simpler and more economical to construct than the profile of a traditional ogee crest. The application of a mitered ogee crest with a stair‐stepped spillway is the subject of the following paper. Currently, there is little research available regarding the design of a mitered ogee crest. This paper discusses the discharge capacity of a mitered ogee crest and its application to stair‐stepped spillways. A comparison of the performance and capacity of a stair‐stepped spillway is made to the design of a traditional ogee crest (Army Corps of Engineers design specifications) and to the design of a broad crested weir. This paper is based on the 1:20 scale sectional and the 1:40 scale spillway physical models of the Gilboa Stair‐Stepped Overflow Spillway, conducted at the Utah Water Research Laboratory, Utah State University. The analysis and comparison of the three types (traditional ogee, mitered ogee, and broad crested weir) of crest designs involved measuring discharge capacities and crest pressures. Each crest was tested for a variety of headwater conditions resulting in a series of rating curves for the assessment of three types of crest designs. Results are also presented in the form of discharge coefficient versus total reservoir head. The performance of the stair‐steps of the spillway was evaluated for energy dissipation, cavitation, and flow interaction with the spillway steps. Analysis indicates that the mitered ogee crest performed considerably well when compared to the traditional ogee crest design. The mitered ogee crest produces 93% of the flow capacity of the traditional ogee crest while the broad crested weir design passed only 72% as much discharge as that of the traditional ogee crest. Therefore, retrofitting the crest of a stair‐stepped spillway with a mitered ogee crest design is a very viable option. However, the spillway transition from the crest to the stair‐stepped spillway is also an important flow performance consideration for all three of the crest types.

Select this Article		Evaluation of Superelevation in Open Channel Bends with Probabilistic Analysis Methods G. R. Shams Ghahfarokhi, P. H. A. J. M. van Gelder, and J. K. Vrijling ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)244 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A probabilistic — and uncertainty analysis for the failure modes of a hydraulic structure is presented in this paper. First, a general approach for such kind of analysis is presented, followed by a case study. The study deals with the Ziaran diversion dam in Iran. Data has been collected during previous studies of this dam. In particular one failure mechanism is investigated in this paper in detail: overtopping by superelevation of the bend flume in the Ziaran Dam. This study focuses on the downstream water surface elevation during the flow considering the flume's actual discharge and roughness. Superelevation in the Ziaran Flume has led to severe erosion of the bank and to undermining of the structure. Therefore, this study aims to cast lights on the cause of overtopping by superelevation. By means of direct observation on the flume's hydraulic performance, during full discharge, and from generalization of the field data, a more reliable prediction method of the magnitude of superelevation has become possible. The probabilistic analysis will show to have several advantages in comparison with deterministic analysis methods.

Select this Article		Research and Design of Renwick Dam Stepped Spillway S. L. Hunt and K. C. Kadavy, P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)245 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The United States Department of Agricultural (USDA) Natural Resources Conservation Service (NRCS) has financially and technically assisted with the construction of nearly 11,000 small watershed dams in the U.S. By 2017, half of these structures will reach the end of their planned service life due to age, and others will need rehabilitation prematurely due to hazard classification changes as a result of urbanization and alterations in land use and topography. In many cases, spillways have inadequate spillway capacities. Approximately 10% of the 11,000 NRCS assisted structures are expected to have roller compacted concrete (RCC) stepped spillways to increase the spillway capacity of the existing structure. Typical RCC stepped spillways for NRCS applications will be constructed on existing embankments where the downstream embankment face slope ranges from 2(H):1(V) to 4(H):1(V). Literature in this realm of stepped spillways is very limited. A specific study utilizing a two‐dimensional, 1:8 scale physical model was conducted to evaluate the design flow in a 4(H):1(V) stepped spillway chute and the effects air entrainment has on the design of the spillway training walls and stilling basin dimensions. Water surface and bed profiles were collected during testing. Observations show that the air entrainment inception point for relatively short spillway chute drops up to 12 m (40 ft) is expected near the bottom of the spillway chute for prototype flows higher than 7.0 m²/s (75 cfs/ft). For these flows, air entrainment is not expected to influence the design of the training walls significantly especially under high tailwater conditions. Spillway drops from 9.1 m to 12.2 m (30 to 40 ft) were tested with both stilling basin and riprap dimensions evaluated for dissipating the remaining flow energy. For the 9.1 m (30 ft) spillway drop, the stilling basin required to dissipate the remaining energy was approximately 36% longer than the stilling basin required for the 12.2 m (40 ft) spillway drop. Additionally, the end sill for the energy dissipating stilling basin for the 9.1 m (30 ft) spillway drop was 2 times the height required for the 12.2 m (40 ft) spillway drop. Yet, the hydraulic performance of the stilling basin for the 9.1 m (30 ft) spillway drop was undesirable, so the spillway was further tested with a drop height of 9.8 m (32 ft). This paper is intended to increase the knowledge and understanding of stepped spillways applied to relatively flat‐sloped dam embankments and dimensioning of the energy dissipating stilling basin and associated riprap in the downstream channel.

back to top

HYDRAULIC STRUCTURES: III

Select this Article		CFD Analysis of Outlet Energy Dissipation Structure at the Big Sand Wash Reservoir — Upalco, Utah K. D. Nielsen, Ph.D., P.E., A. L. Davis, Ph.D., P.E., and K. D. Beecher, P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)246 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Rapid advances in state‐of‐the‐art computational fluid dynamics (CFD) analyses are being made in simulating multi‐phase flow fields, particularly where fluid‐structural member interactions, air‐water interfaces (free surfaces), and bubbly mixtures are involved. Coupled equations link the Navier‐Stokes equations of fluid motion with structural deformation equations to simulate both fluid and structural response to either steady‐state or transient boundary conditions. Consequently, defensible calculations that are based on the best formulas used in engineering practice can be utilized for comprehensive hydraulic structural design. Problems associated with frothy free surfaces and bubble formation can now benefit from CFD implementation of research results regarding two‐phase, air‐water flow. A case study which illustrates the benefits of CFD analyses to guide difficult hydraulic structure designs is presented. The case study consists of flow through fixed cone valves (sometimes called Howell‐Bunger or ring jet valves) into a stilling basin. These turbulent discharge conditions cause undesirable spray. CFD analyses were used to evaluate performance improvement options and assist with the final design alternative.

Select this Article		The Folsom Dam Auxiliary Spillway Physical Model Study as a Design Tool Su Mishra, Ph.D., P.E., M. ASCE, Steven L. Barfuss, P.E., M. ASCE, William J. Rahmeyer, Ph.D., P.E., M. ASCE, Harold Huff, P.E., M. ASCE, Tom Smith, P.E., M. ASCE, and Nathan Cox, P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)247 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Folsom Dam is on the American River about 20 miles northeast of Sacramento, California. The dam was designed and built by the Corps of Engineers (COE) and transferred to Reclamation for operation and maintenance in 1956. The dam is a concrete gravity structure 340 ft high and impounds a reservoir of a little more than one million acre‐ft. The existing dam features two tiers of four outlets each, controlled by 5‐ by 9‐ft slide gates having a discharge capacity of approximately 700,000cfs. Updated PMF calculations require a total flood discharge in excess of 1,000,000cfs. To safely pass the PMF, an auxiliary spillway is proposed and as a design tool to ensure safe and efficient operation of the structure, a physical model study was utilized. Physical modeling was performed on the upstream portion of the proposed auxiliary spillway near the left abutment of Folsom Dam. The auxiliary spillway control structure will contain six submerged tainter gates (also known as top‐seal radial gates) that can discharge about 300,000 cfs at a maximum pool elevation of 481 ft. Ayres Associates and Utah State University, with guidance from the USACE have utilized a physical model of the auxiliary spillway and the approach channel in the reservoir as a design tool.

back to top

HYDRAULIC STRUCTURES: IV (INLETS/OUTFALLS/DROP SHAFTS)

Select this Article		A.R. Bowman Dam Outlet Modifications — Lessons Learned Jonathan P. Burgi, P.E., M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)248 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Ochoco Irrigation District (District) operates and maintains Arthur R. Bowman Dam, an earth fill dam constructed by the Bureau of Reclamation between 1958 and 1961. Bowman Dam is located on the Crooked River near Prineville, Oregon and forms Prineville Reservoir. The District operates Bowman to fill during spring snowmelt runoff and for release of stored water during summer irrigation season. The outlet works tunnel is located in the right abutment and bifurcates into a gate chamber consisting of two 1.22 m (4 ft) by 1.82 m (6 ft) emergency gates and two 1.22 m (4 ft) by 1.82 m (6 ft) regulating gates. A training wall extends 9.14 m (30 ft) from the gate chamber and separates the flow exiting the two gates. The high‐velocity flow is released into a 121.92 m (400 ft) long 3.35 m (11 ft) wide horseshoe shaped outlet tunnel. Historically, OID has shut off all of the water to the Crooked River to perform routine maintenance on the gates and outlet tunnel. As part of the Settlement Agreement for the Pelton Round Butte Hydroelectric project, Mid‐Columbia Steelhead are scheduled to be released in the Crooked River in the spring of 2008. With increased concern over wildlife habitat in the Crooked River, the Bureau of Reclamation and the District needed a solution to allow minimum stream flow to pass through the outlet works during routine maintenance. The Bureau of Reclamation recommended to the District the construction of a 1.22 m (4 ft) high “splitter wall” to run the length of the outlet tunnel downstream from the gates. As part of the Districts' maintenance agreement, the District contracted with David Evans & Associates, Inc. (Engineer) to design the slitter wall. In addition to the splitter wall, DEA was challenged to design a safe and functional method to by‐pass a minimum of 1.13 m³/s (40 cfs) through the tunnel during construction on the splitter wall. Construction challenges included working within agreed upon 2 hour shut down periods, dissipating the energy exiting the control gate and redirecting the flow into a temporary by‐pass pipe thus creating an acceptable work environment within the outlet tunnel. The completion of the tunnel splitter wall project provides safe access to either side of the downstream outlet tunnel while flows up to 5.66 m³/s (200 cfs) pass by on the other side of the wall and on to the Crooked River. This paper will review the project from conceptual design through construction and evaluation. The author will share his experience in working in conjunction with the irrigation district highlighting successes, failures and lessons learned.

Select this Article		CFD Analysis of Vortex Dropshaft Structure K. D. Nielsen, Ph.D., P.E. and A. L. Davis, Ph.D., P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)249 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Management of large sewer system flows often entails surface collection systems in conjunction with deep tunnels for storage and conveyance. Vertical dropshafts are used to transport water from the surface systems to the deep tunnels. Good dropshaft performance is a critical component of the overall system performance. In addition to simply conveying flows from surface systems to tunnels, dropshafts affect energy dissipation and entrained air release. Vortex dropshafts are frequently used because of their excellent energy dissipation and air removal characteristics. Because of the complex hydraulics associated with vortex dropshafts, physical model studies have often been used to help evaluate dropshaft performance and provide design guidance. However, CFD analysis is beginning to supplement or replace physical models, because CFD models can be assembled more quickly, provide greater visualization capabilities, are less costly, and are not subject to some of the physical model scale effects. For design of the Milwaukee dropshafts, CH2M HILL utilized physical models developed in the early 1980's at the University Of Iowa, Iowa Institute of Hydraulic Research (IIHR). CH2M HILL has designed several additional dropshafts since these original model studies were performed. Because of site considerations, dropshaft designs often deviate in some respects from the Milwaukee model tests. Hence, CFD simulations have been used to assist with the design of these dropshafts. To provide model verification, a CFD model of the physical model constructed at IIHR was developed. This paper compares CFD model simulations and IIHR physical model results.

Select this Article		Experimental Study on a Plane Free Overfall F. M. Renna, U. Fratino, A. F. Piccinni, and G. Balacco ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)250 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract This paper deals with the analysis of collected experimental data on free overfall in sub‐critical and super‐critical flow conditions, using the analytical and empirical approaches available by the technical literature. The aim is to provide new informations and tools useful to design correctly a single drop hydraulic structure.

Select this Article		Novel Drop Shaft System for Conveying and Controlling Flows from High Level Sewers into Deep Tunnels Robert Andoh, Kwabena Osei, Jeremy Fink, and Mike Faram ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)251 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The paper describes a novel drop shaft system that relies on the use of a self‐activating, non‐powered and no moving part air intake control system to prevent instabilities and provide smooth transitions between air‐entrained vortex flow modes and pipe full operating modes. This allows more compact drop pipe arrangements to be deployed within a single drop structure, also providing for maintenance access. These systems therefore do not require auxiliary maintenance or air shafts resulting in significant project cost savings. Further optimization of the system has involved the use of compact hydraulic break, rotary flow energy dissipation structures at the base of the vertical drop pipes resulting in a space efficient and effective system for controlling flows into deep tunnels. The operational characteristics of the novel drop shaft system including the basis for more effective flow control and elimination of unstable flow conditions are described in detail in this paper. The paper also includes case studies of its successful application in a number of deep tunnel schemes and at a wastewater treatment plant.

Select this Article		Optimize Pump Intake Design with Formed Suction Inlets Yifan Zheng, P.E., M. ASCE and David Werth, Ph.D., P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)252 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Vertical wet pit pumps have been frequently used for cooling tower type pump intakes requiring the need for a vertical transition from the shallow cooling tower basin to the deeper pump pit. Given the sensitivity of approach flow condition toward the wet pit pumps, cooling tower type pump intakes tend to have a large intake footprint and higher submergence depth. Over the past several years, it has been found that the use of formed suction inlet (FSI) can result in a more compact and economical pump intake with substantially reduced intake footprint and may also result in a lower submergence depth. The US Army Corps of Engineers Type 10 FSI is commonly used as it offers several advantages such as improved approach flow hydraulics in high cross flow conditions, less sensitive to the skewed velocity distribution at its entrance and also has excellent subsurface vortex suppression capabilities. This paper presents the results of hydraulic design related to two cooling tower pump intakes; one uses traditional vertical wet pit pumps and the other uses vertical pump with a FSI. Both intakes have similar application requirements and pump capacities. Model results confirm that the use of the FSI results in the reduction of the footprint of the intake structure by 38% and a more than 5‐ft reduction in submergence requirements. In addition, physical sump model testing on the pump intake with FSI is briefly described.

back to top

HYDRAULIC STRUCTURES: V

Select this Article		Flood Damage Reduction of Debris Flows for the City of Aguadilla Using Concrete Crib Dam and Channel Improvements David Weston, P.E. and Rafael Velez ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)253 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The Rio Ojo de Agua Flood Control Project was authorized to reduce flood damages to the historic municipal area of Aguadilla in Puerto Rico. Frequent storm events impacts the area with flooding and large sediment loads, which include large rocks and debris. The impacted area is highly urbanized with several significant historical sites that need to be preserved. At the upstream portion of the project, where the Rio Ojo de Agua flows through a mountainous ravine, a concrete crib dam was designed to contain large rocks and debris. Downstream of the crib dam, the water will flow under a high velocity flow regime through an existing historic railroad culvert/tunnel into a supercritical open channel and then into a covered channel beneath the existing roads to avoid impacts to adjacent historic buildings, park, and spring. The outfall of the covered channel will be near a newly constructed harbor at Aguadilla Bay. During these frequent storm events, these high velocity flows will most likely have an effect on navigation near the outlet and cause conditions for excessive scour. Therefore, energy dissipation of those velocities was investigated as well. A variety of hydraulic design criteria and one‐dimensional (1D) and two‐Dimensional (2D) hydraulic models were used to analyze and design the proposed project features. This paper will describe hydrologic and hydraulic analyses performed to design a project to reduce damages due to flooding and debris.

Select this Article		Investigation of Flow and Local Scour Characteristics around a Partially Submerged Permeable Barb A. N. Papanicolaou and J. F. Fox ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)254 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Barbs are wide crested trapezoidal structures, typically constructed of riprap gravel, which project out from the streambank and are oriented upstream into the main flow. Barbs reduce erosion along streambanks by deflecting current into the center of the channel aiding in the protection of bridge piers and abutments. The overall objective of this study is to establish design criteria for permeable barbs within non‐navigable mild sloped gravel bed streams. The paper consists of two major parts. Part one focuses on the flow characteristics around a submerged permeable barb to understand the flow regimes “formed” within the vicinity of a barb. Part two utilizes the quantitative data that are gathered in part one and investigates the complex evolution of local scour around the permeable barb under clear‐water scour conditions.

Select this Article		Reduction of Local Scouring with Protective Spur Dike H. Karami, A. Ardeshir, M. Saneie, K. Behzadian, and F. Jalilsani ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)255 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract One of the main parameters in design of spur dikes is the estimation of local scour depth around their tail. Spur dikes are usually built in series and their stability depends on the stability of the first spur dike. In this research, an experimental investigation is carried out in order to reduce local scouring around the first spur dike in a series of spur dikes (4 spur dikes). A smaller protective spur dike perpendicular to the flow direction is proposed to substantially reduce the local scouring. All experiments are performed in the experimental flume with moving bed. Also, all the spur dikes are rigid, and are made of pressurized plywood, straight and non‐submerged. For various experimental lengths (L) and distances (X) of the protective spur dike, different value of relative velocity () is calculated. Finally, in favor of statistical analysis which has been done on the experimental data, an empirical equation for the relative scouring is derived.

back to top

HYDRAULIC STRUCTURES: VI (DAMS)

Select this Article		A Dam Breach Model of Epic Proportions‐Simulating the Glacial Lake Missoula Floods Christopher R. Goodell, P.E. and Gary W. Brunner, P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)256 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The Columbia River Gorge and the Scablands of Eastern Washington are just two of the incredibly stunning geologic features carved out by the great Missoula Floods approximately 10 to 40 thousand years ago. These floods of epic proportions were triggered by the “failure” of a massive glacial ice dam that impounded a lake about the same size as the Great Slave Lake in Canada. With the improvements of available GIS data and dam breach modeling capabilities in HEC‐RAS, a hydrodynamic model was constructed of this enormous flood stretching from Eastern Montana to the Pacific Ocean. The results of this model shed light on some of the enormities of this flood event, specifically the magnitude of discharge, flow velocities, and inundation extents. In addition, the progression of the flood wave through Eastern Washington, the Columbia River Gorge, up the Willamette River Valley and out to the Pacific Ocean is demonstrated through GIS.

back to top

INTERNATIONAL AND TRANSBOUNDARY ISSUES

Select this Article		An Algorithm for Evaluation of Water Resources Development Projects Using Value Engineering Mohammad Karamouz, Asghar Elyasi, and Azadeh Ahmadi ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)257 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Major investment is involved in water resources projects, therefore Value Engineering (VE) could be an effective tool in design new projects and re‐evaluation the projects under construction and development. Value Index (VI), an indicator in VE, is originally defined as the ratio of functionality and quality to cost. It could be used for the purpose of assessing the lowest Life Cycle Cost (LCC) consistent with the required performance, reliability, quality, environmental sensitivity, and water safety and accuracy. Even though, water resources developments could be technically successful, they could encounter problems by failing to meet the socio‐economic aspects and may not be able to obtain a broad base of stakeholders' satisfaction. One way to solve this problem is to have a system approach to these projects by showing how variation in design parameters that are affected by population growth, available water resources, land use and economic factors can alter the fundamental elements of the projects. The principle of system dynamics could be used to see how the system interacts with the socio‐economic as well as physical variability. In this paper, an algorithm for evaluation of a water resources project and selecting the best alternatives considering value engineering principles are discussed. Applying system dynamics techniques as a tool for simulation of different scenarios can help managers consider the effects of different governing factors. The proposed procedure is applied to a water development project in the central part of Iran.

Select this Article		An Ancient Struggle: A Game Theory Approach to Resolving the Nile Conflict Laila Elimam, David Rheinheimer, Christina Connell, and Kaveh Madani ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)258 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The Nile River has been the center of water resources development tensions among four main riparian actors: Egypt, Sudan, Ethiopia, and other upstream nations. Each player has a desire to meet its national demands under increasingly stressed limited resources. Egypt, the most powerful of the actors, strives to maintain the status quo: securing the water supply that is barely sufficient for its growing population. Sudan is wedged between its 1959 treaty with Egypt and potentially economically beneficial cooperation with Ethiopia. Ethiopia, the source of most of the Nile, strives to increase its water share to secure its food supply and facilitate economic development. Finally, the upstream nations seek to be released from the water development restrictions placed on them by the current system. All nations fear retaliation from Egypt. This study applies game theoretic methods to study this interstate water problem using the Graph Model for Conflict Resolution, which provides insights into the strategic behaviors of the conflicting parties. The developed model attempts to determine most likely outcomes of the conflict given the nations options and preferences. Results indicate that the current situation is not stable and that stable outcomes include retaliation by Egypt. A sensitivity analysis shows that the model is highly sensitive to Egypt's preferences, however, but not very sensitive to Sudan's or Ethiopia's preferences.

Select this Article		Evaluation of Water Management Scenarios for the Rio Grande/Bravo S. Sandoval‐Solis, D. C. McKinney, and H. Sanvicente‐Sanchez ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)259 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Due to the scarcity of the water resources in the Rio Grande/Bravo basin, alternative water management policies or “Scenarios” have been evaluated to determine their hydrologic feasibility and the individual or joint benefits to water users in the basin. The policies evaluated are proposals of stakeholders, local water management agencies, technicians, and experts in Mexico and the United States. Scenarios include water rights buybacks, groundwater banking through in lieu recharge, allocation of non‐treaty tributary flows toward treaty delivery obligations, and allocation of water savings from agricultural water conservation. For example, the in lieu groundwater banking method is defined by the surface water available in the basin. If there is enough surface water available, recharge is accomplished by curtailing groundwater pumping and providing surface water to water users. On the other hand, if there is not enough surface water, groundwater and surface water are used to meet the water demands. The evaluation model has been constructed in the Water Evaluation and Planning system (WEAP). Various hydrological conditions, such as normal, wet or dry, have been defined to compare the performance of the proposed policies with the current water management policies under different hydrological conditions. The scenarios and their evaluation are presented along with a comparison against the current water management policies.

Select this Article		How Investment in Wastewater Infrastructure Has Improved Water Quality along the Mexico‐Texas Border Marcel Dulay, P.E. and David Eaton, Ph.D. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)260 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract When Mexico and the US agreed to NAFTA the two nations expected economic growth to occur with some adverse environmental effects. The two parties agreed to an environmental side agreement to create BECC/NADB to cooperate with existing water institutions to address water pollution. Mexican, US, and bilateral agencies have invested over $1.5 billion between 1999 and 2005 in water and wastewater (W/WW) infrastructure along the Texas‐Mexico border. This infrastructure has affected water pollution in the Rio Grande, the international border. This paper reports on sources of funds, characterizes W/WW infrastructure investment, and documents water quality improvement. Improvements in water quality occurs where infrastructure has been added and continuing water quality problems occur where infrastructure investments have yet to be made or have been overwhelmed by regional population growth. This paper is based on information gathered for an EPA report on the impacts of water‐related infrastructure along the Mexico‐Texas border.

Select this Article		Retracted:Trans‐Boundary Water Sharing of the Ganges River: A Regional Planning Approach Bhuiyan M. Alam ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)261 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Fresh water sharing of common rivers or water bodies like lakes/reservoirs among the concerned countries are always a critical issue worldwide and requires rigorous information‐based analysis to reach a common and acceptable agreement. In the context of trans‐boundary rivers, the situation of Bangladesh is unique. Being a small country with only about 144,000 sq. km. area, it contains 57 trans‐boundary rivers out of which 54 are along the India‐Bangladesh border and the rest three are along Myanmar‐Bangladesh border. Most of the fresh water flow in the major rivers is from the contribution of watersheds lying out side Bangladesh. Fresh water flow in the trans‐boundary rivers vary greatly from almost zero in the dry season to about 80,000 cumecs in the monsoon. Reduction of fresh water supply in the dry season causes chronic economic, social and environmental hazards in the lower riparian region which results indescribable distress to the people. This paper discusses the needs and sharing issues of fresh water in the trans‐boundary river systems along Indo‐Bangladesh boarders with specific reference to Ganges River water. It proposes that the countries sharing the Ganges‐Brahmaputra‐Meghna River Basin take a regional approach, instead of taking several bilateral approaches that have failed to fulfill the needs of the people of this region.

back to top

INTERNATIONAL CONFLICT RESOLUTION/CASE STUDIES

Select this Article		Bargaining over the Caspian Sea — The Largest Lake on the Earth Majid Sheikhmohammady and Kaveh Madani ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)262 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The Caspian Sea is considered by some to be the largest lake in the world. This multinational water body is the subject of one of the world's most intractable disputes, involving Azerbaijan, Iran, Kazakhstan, Russia and Turkmenistan. The conflict over the legal status of the Caspian Sea emerged after the collapse of the Soviet Union and has not been resolved yet. This paper intends to provide some insights into the conflict and predict the most possible outcomes of the negotiations based on Social Choice rules and Fallback Bargaining procedures. In this study, the five options for resolving the conflict which has been suggested during the negotiations are introduced and discussed. Some well‐known social choice rules including Condorcet Choice, Borda Scoring, the Plurality Rule, Median Voting Rule (MVR), Majoritarian Compomise (MC) and Condorcet's Practical Method (CPM) are applied to find the “socially optimal” resolutions of this conflict. Then some different versions of Fallback Bargaining methods which seek minimizing the maximum dissatisfaction of any bargainer are applied to predict the outcome of the negotiations. Finally, the socially optimal resolutions are compared with Fallback Bargaining methods' results and the advantages and disadvantages of each method are discussed.

Select this Article		Impacts of River Morphology Changes on Floodplain Zoning: A Case Study Mohammad Karamouz, F. ASCE, Navideh Noori, and Ali Moridi ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)263 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Flood is a natural event which depends on numerous parameters, and affects floodplain land use planning based on an acceptable level of risk. In order to predict the extent of the floodplain, it is necessary to consider flood characteristics including flood return periods. One of the most important parameters in floodplain studies is how to deal with the variability of river cross sections and considering their effects on the uncertainties of river engineering studies, which has not been emphasized much in previous works. Because of the variation in river morphology due to erosion and sedimentation during major floods, hydraulic routing of the flood is affected by the variations in cross sections. The HEC‐RAS simulation model is used to investigate the flood plain variations. In this paper, floodplain zoning at the Pirsohrab plain located in the south‐eastern part of Iran is investigated. Sensitivity analysis on river cross sections is done for predicting the critical reaches of the river. Based on the results of this study, recommendations are given to reanalyze the placement of a pressure irrigation network supported by levee construction.

Select this Article		Transboundary Cooperation and Dispute Management of Water Resources in the Danube River Basin Philip Weller and Mihaela Popovici ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)264 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Throughout history, the Danube River has always been the most important European River. From its source to its mouth, the Danube River and its tributaries serve as a resource for various water uses, such as supplies for drinking water and industry, energy production, transport, agricultural irrigation and wastewater. In addition, the Danube River, together with the delta, supports areas of high biological diversity that are not only important for such activities such as tourism, fishery and forestry, but also provides a home for large amounts of animal and plant species.

back to top

INTERNATIONAL OUTREACH, HYDROPHILANTHROPY, AND GOVERNANCE OPPORTUNITIES

Select this Article		Clean Water and Sanitation Projects Empower Rural Communities Philip H. Burgi, P.E., Hon. M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)265 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Deficiencies in water supply and sanitation significantly hamper economic opportunities and decrease the quality of life in most rural communities worldwide. Despite the progress made in water and sanitation during the past ten years, and despite the fact that clean water has been recognized as a human right by the international community, one‐sixth of the world's population is still without clean water and two‐fifths are without adequate sanitation. The ability to wash one's hands and drink clean water has a major impact on family hygiene and health. Women, who play an especially important role in gathering water for their families, are often those that bare the heaviest burden. Because people who are poor are most likely to get sick, and ill health perpetuates poverty, the lack of clean water and sanitation triggers a vicious cycle that hampers economic and social development in rural communities. There are many non‐governmental organizations (NGOs) as well as governmental agencies addressing the challenge of clean water and sanitation in rural communities. However, the task is staggering. This paper defines issues as well as goals for rural water and sanitation projects in developing countries as well as presents some of the barriers to their sustainability. The author has worked with several NGOs in the development and assessment of rural water and sanitation projects in Guatemala, Honduras, Bolivia and Ecuador. The paper defines criteria for project sustainability, describes barriers to clean water and sanitation, and gives witness to empowered rural communities that have developed their own clean water and sanitation projects. People in rural communities around the world are being empowered by the three‐legged stool concept of clean water, sanitation, and basic hygiene training. It is important that the rural community and those assisting understand before the project is initiated the funding options, local governmental policies and politics, community leadership dynamics, customs, culture, community location with respect to water sources, planning for growth, and protection of the source watershed.

Select this Article		Looking Ahead to the 5^th World Water Forum — Istanbul 2009 Mark W. Killgore, P.E., Daene McKinney, Ph.D., P.E., and Jerome Delli Priscoli, Ph.D. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)266 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract This paper will discuss preparations by EWRI and IWR for the 5th World Water Forum. Several potential WWF5 themes are being considered. Currently, the WWF5 sessions are divided into several broad thematic areas, including: 1. Water Security Adapting to Climate Change and Risk Management Protecting Resources, Livelihoods and Biodiversity Financing Water Infrastructure and Services; 2. Water Management and Governance Improving Management of Water Services and Resources Improving Water Governance Innovation and Water Technologies Equity, Education and Ethics; 3. Water Use and Impacts Health, Sanitation and Water Supply Food Security, Water for Food, and Ecosystems Water for Energy — Energy for Water; 4. Basin Management and Development; 5. Wild Card Themes. Although planning for US particpation is just beginning, EWRI has engaged both the AWRA and Corps of Engineers in discussions about our possible approach. One rich source of material may be the AWRA sponsored US Water Policy Dialogue in possible combination with Canadian and Mexican policy views. ASCE has taken positions in several areas of water policy as well. To prepare for our World Water Forum involvement, the Corps, AWRA and EWRI are planning a series of meeting to characterize key issues and flesh out important questions facing water managers and policy‐makers in North America.

Select this Article		Planning for UNESCO IHP VII: Challenges and Opportunities Mohammad Karamouz, F. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)267 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The International Hydrology Program of UNESCO has started their seventh 5 year plan in 2008. This phase of IHP focuses on water dependencies: systems under stress and societal responses to them because of growing water need and limited water resources with adequate quality. Five themes are considered in this phase of IHP. In the first Theme, the climate change effects on surface and groundwater resources are evaluated especially in arid and semiarid regions. The feedback mechanism of hydrologic cycle in stress is identified using hydrological research and also the effects of climate change on hydrological extremes and the resulted hazards. Water governance and water resources management go beyond utilization of existing structures and the physical limits of water resources systems to include technical, social, political and economics aspects for better resources management. This is included in Theme 2. The main aspects that must be considered for water governance are conflict resolution, water equality and public participation. The anthropogenic impacts on the urban ecohydrology and environment including processes and interactions in the urban water cycle are focused in Theme 3. In this theme, the water role in changing landscape such as erosion, solvability and regulation in biogeochemical cycles are targeted. In the 4th theme, the focus is on development of strategies and methodologies to supply safe water with high quality standards, for domestic, human health and food production purposes. In the last theme activities for water education to improve communications, public awareness and training are included. In this paper the themes of IHP VII plan will be discussed addressing certain challenges and opportunities for the developing countries.

back to top

JAPAN‐US COLLABORATION: ADAPTATION TO CLIMATE CHANGE, DROUGHT, AND RISK REDUCTION

Select this Article		Can Indications of Climate Change Impacts Be Detected from Recent Phenomena in Japanese Coasts? K. Noguchi, F. Kato, and S. Tsuchiya ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)268 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The IPCC 4th assessment report (2007) reveals the global warming caused by human actions. The current situation will change gradually; however, it will accelerate gradually to a situation never experienced before. This implies a collapse of the preconditions for disaster prevention work. Our final aim is to establish an adaptation methodology for the coastal prevention policy in Japan. The purpose of this study is to determine climate change signs and effects. First, wind changes between the future climate and present climate are analyzed by earth simulator results. Second, the wave climate historical change is re‐analyzed for the data of five observation stations around the Japanese coast. We suggest the growth of wave climate in recent years and prove its relation with climate change by a comparison between the present and future wind outlines using the earth simulator.

Select this Article		Hydrologic Effects of Climate Change in the Yukon River Basin L. E. Hay and G. J. McCabe ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)269 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A monthly water balance (WB) model was developed for the Yukon River Basin (YRB). The WB model was calibrated using mean monthly values of precipitation and temperature derived from the Precipitation‐elevation Regression on Independent Slopes Model (PRISM) data set and by comparing estimated mean monthly runoff with runoff measured at Pilot Station, Alaska. Potential hydrologic effects of climate change were assessed for the YRB by imposing changes in precipitation and temperature derived from selected Inter‐governmental Panel for Climate Change (IPCC) climate simulations. Scenarios from five general circulation model (GCM) simulations were used to provide a range of potential changes. Results from the scenarios indicate an increase in annual runoff in the 21^st century for the YRB with simulated increases in precipitation having the greatest effect on increases in runoff. Simulated increases in temperature were found to alter the timing of snow accumulation and melt.

Select this Article		Management Strategies for the Colorado River Reservoir System under Major Drought Scenarios Donald K. Frevert, Terrance J. Fulp, Jose D. Salas, Jim Prairie, and Jeff Lukas ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)270 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The Colorado River system of the western United States is a heavily appropriated network of rivers, reservoirs and diversions serving a water short region with major municipal and agricultural demands. Management of these very limited water resources in the Colorado River Basin has been a subject of great interest to hydrologists, water resource engineers, meteorologists and scientists in other related fields for a number of years — but never quite so much as today, with the drought of record plaguing the basin. The severity of the current drought has led managers and technical experts in the water resources community to question how common this event might actually be, and has inspired substantial debate as to how best to manage the reservoirs of the basin to deal with such droughts now and in the future. A technical work group composed of experts from government, the academic community and the private sector has come together to focus on these questions, and a variety of methodologies (parametric and non‐parametric stochastic hydrology and tree‐ring analysis) have been used to evaluate the frequency of major droughts such as the current one. Public meetings and other interactions with partners and stakeholders has yielded a series of potential strategies which will be considered by the Bureau of Reclamation in future shortage situations. This presentation will describe the process, findings, and conclusions reached to date and future steps toward implementation of shortage criteria for the basin.

Select this Article		Restoration Attempt of Submerged Macrophytes in an Eutrophic Shallow Lake in Japan Kunihiko Amano, M. ASCE, Tetsuya Oishi, M. ASCE, and Toshikazu Tokioka, M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)271 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract We have tried to develop a procedure to rehabilitate submerged macrophytes in lakes and marshes where they had been disappeared. Diaspore of submerged macrophytes from bottom sediments should be retrieved and used to restore locally native species. We investigated the distribution of the density of diaspore in lake bottom sediments and the germination potential of diaspore in Lake Kasumigaura, Japan. We have shown that the densely distributed diaspore was found in the vicinity of the river mouths and bays. Germination tests for sediment samples taken from several depths showed that the density of diaspore was high at the depth of 20–50cm from sediment surface, and the number of germination of submerged macrophytes was high at the depth of 10–40cm from sediment surface. Age determination of the bottom sediment showed that these sediment layers were deposited during periods when submerged plants were dominant in the lake. This result implies the possibility of the rehabilitation of native submerged macrophytes from diaspore in bottom sediments in Lake Kasumigaura.

Select this Article		The Glen Canyon Dam Temperature Control Device: Restoring Downstream Habitat for Endangered Fish Recovery Tracy B. Vermeyen, P.E., M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)272 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Prior to closure of Glen Canyon Dam in 1963, the temperature of water flowing down the Grand Canyon each year varied from near freezing to 30°C during the heat of summer. Since construction of the dam, cold water (7 to 10°C) has been released from the deeper levels of the reservoir. For several miles below the dam, these cold water releases have created an excellent tailwater trout fishery. But as the water flows downstream through the Grand Canyon, it only warms to about 15°C which is not warm enough to allow endangered native fish species, like the humpback chub (Gila cypha), to reproduce and thrive in the Colorado River. Researchers believe that increasing the water temperature from Glen Canyon Dam is an important component in restoring habitat for the humpback chub and other native fish in the Grand Canyon. However, biologists fear that increasing river temperatures may encourage nonnative warm water fishes to move up the Grand Canyon or stimulate parasites or other disease agents that are currently controlled by colder water. A TCD (temperature control device) retrofit to Glen Canyon Dam would allow operators to adjust release water temperatures to improve habitat and to minimize potential negative impacts of cold water releases. The decision to construct a TCD will involve considering the potential that warm water releases will create unacceptable levels of competition or predation by nonnative fishes, the introduction of diseases or parasites that could negatively impact the humpback chub or other species of concern. Currently, the risk versus reward of adding selective withdrawal capability to Glen Canyon Dam is being evaluated by the Glen Canyon Dam Adaptive Management Program, regulatory agencies and stakeholders.

Select this Article		Warming and Implications for Water Supply in the Colorado River Basin Gregory J. McCabe and David M. Wolock ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)273 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The high demand for water, the recent multiyear drought (1999–2007), and projections of global warming have raised questions about the long‐term sustainability of water supply in the southwestern United States. In this study, the potential effects of specific levels of atmospheric warming on water‐year streamflow in the Colorado River basin are evaluated using a water‐balance model, and the results are analyzed within the context of a multi‐century tree‐ring reconstruction (1490–1998) of streamflow for the basin. The results indicate that if future warming occurs in the basin and is not accompanied by increased precipitation, then the basin is likely to experience periods of water supply shortages more severe than those inferred from the long‐term historical tree‐ring reconstruction. Furthermore, the modeling results suggest that future warming would increase the likelihood of failure to meet the water allocation requirements of the Colorado River Compact.

back to top

JAPAN‐US COLLABORATION: AQUATIC ECOLOGY

Select this Article		Aerating Circulation as Measures for Blue‐Green Algae in Dam Reservoirs Shinsuke Unisuga and Kaoru Takeya ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)274 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract In recent years, phytoplankton increases extraordinarily almost every year, caused by eutrophication in dam reservoirs which are managed by Japan Water Agency (JWA). In particular, blue‐green algae are causing serious problems including deterioration of landscape, deterioration of drinking water quality due to foul smell and taste, interference of water purification plants and disorder of agricultural water service system. JWA has been carrying out measures to tackle with these problems. As one of measures, JWA installed aerating circulation facilities and is operating them in dam reservoirs to restrain the outbreak of blue‐green algae. The effectiveness is observed to a certain degree. This report outlines the mechanism of restraining the blue‐green algae growth by aerating circulation facilities, and describes the interim research findings of water quality improvement by showing data of the vertical distribution of water temperature in the reservoirs and downward trend of the cell count in species of algae.

Select this Article		Evaluation of Aquathol K Efficacy on Sago Pondweed in the Ogilvy Ditch John E. Boutwell, David Sisneros, and G. Chris Holdren ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)275 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The Ogilvy Ditch and Land Company (ODLC) located in Weld County, near Greeley, Colorado, is experiencing flow restriction in their primary irrigation canal due to a severe infestation of sago pondweed (Stuckenia pectinatus), a native plant species to North America. The U.S. Bureau of Reclamation, Environmental Applications and Research Group, of the Technical Service Center in Denver, Colorado and Uniphos Agro‐Chemical Industry (Uniphos) offered to help the ODLC with their aquatic weed problem. Uniphos is seeking to register Aquathol K products in the 17 western states for use on irrigation canal systems. This was a cooperative study between Reclamation, Uniphos and the ODLC and was of benefit to all three parties. One formulation that is being considered for registration is Aquathol K (dipotassium salt of endothall) to provide control of sago pondweed and other rooted macrophytes in irrigation canals in the 17 western states. Aquathol K has the current EPA Registration No. 4581‐204 and is currently registered as an aquatic herbicide for use in ponds and lakes, where the water can be controlled, by the Environmental Protection Agency (EPA) but it is not register for use in primary irrigation canals. The U.S. Army Corps of Engineers, at the Waterway Experiment Station in Vicksburg, Mississippi, is also involved in this research and has been developing laboratory data on concentration and exposure rates of various herbicides used on sago pondweed including Aquathol K an endothall compound. During this study, it was the responsibility of the Bureau of Reclamation to evaluate the efficacy of Aquathol K, monitor the exposure times during the application and monitor the water quality of the canal. Uniphos set up an herbicide injection system and collected water samples to be analyzed for herbicide concentration. Crop tolerance data (collected during other studies in other locations), water residues, and efficacy data will all be submitted to E.P.A. as part of the registration package for using endothall products in irrigation systems in the 17 western states.

Select this Article		Review of the Performance of the Artificial Floating Island as a Restoration Tool for Aquatic Environments K. Nakamura and G. Mueller ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)276 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Artificial Floating Islands (AFIs) are vegetated floating platforms used in lakes, ponds and reservoirs to enhance the aquatic environment. AFIs have four functions: 1) water purification, 2) habitat enhancement, 3) shoreline erosion protection, and 4) improved landscape features. This paper reviews the performance of AFI. Although AFI can be found in many countries (e.g. China, England, Germany, Japan, Korea, and Taiwan) they are most prevalent in Japan where more than 70,000 m² of AFI structures exist. AFI provides critical habitat for birds and provide important substrate for spawning fish. However, water quality enhancement is their most important feature, especially in Asia where their installation over large surface areas (10 to 30%) of lakes and reservoirs help mitigate the effects of eutrophication. Their shade helps to decrease phytoplankton, while their vegetation helps in nitrogen reduction. The crucial advantages of AFIs are that they float and adapt to water level fluctuations in reservoirs and the reduce predation risks by providing safe, inaccessible refuges for nesting birds.

Select this Article		The Impact of Winter Drawdown on Macrophytes in a Colorado Reservoir G. Chris Holdren and David Sisneros ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)277 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Nuisance growth of aquatic plants was noted within one year after Shadow Mountain Reservoir was constructed in 1946, and complaints about high macrophyte densities have continued intermittently since that time. An evaluation of potential management measures identified winter drawdown as the most practical control technique, although several factors complicate implementation of a drawdown in Shadow Mountain Reservoir. Results are presented for a drawdown conducted in 2006. Both average plant height and plant coverage were significantly reduced in the year following the drawdown. Additional monitoring is planned to evaluate the longevity of macrophyte control.

back to top

JAPAN‐US COLLABORATION: WATER‐RELATED DISASTERS AND FLOOD HYDROLOGY

Select this Article		Current Status of River Discharge Observation Using Non‐Contact Current Meter for Operational Use in Japan Kazuhiko Fukami, Takayuki Yamaguchi, Hitoki Imamura, and Yoichi Tashiro ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)278 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Experiments of continuous flow rate measurements using non‐contact Doppler‐type current meters were made during floods in three rivers of Japan. As a result of the study, the authors have confirmed that the Doppler‐type current meters can be utilized as substitutes for the float method which has been being conventionally applied for flood flow measurements in Japan. Furthermore, it is also indicated this kind of non‐contact current meter can detect the H‐V loop relations during floods and the change of hydraulic conditions of the observation section such as river bed and its roughness.

Select this Article		Development of Integrated Flood Analysis System (IFAS) and Its Applications Tomonobu Sugiura, Kazuhiko Fukami, and Hironori Inomata ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)279 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract In countries where river improvements are not sufficient, smooth evacuation from flooding is important for decreasing loss of life and properties. However, the development of flood forecasting and warning system has not advanced properly because of the financial difficulty, the lack of rainfall data. The authors are developing the fundamental tool for flood forecasting system using GIS data and rainfall data observed by satellites. Although it is necessary to improve about the accuracy of the runoff calculation using these data, it is found that these data are applicable to flood forecasting from verification results of runoff calculation at some basins. This system implements the interface to input satellite‐based rainfall data, the GIS modeling function, the default runoff analysis model, and the output interface to display results, which enables runoff calculation necessary for flood forecasts and alerts rapidly and effectively.

Select this Article		Fundamental Studies for River‐Training Works Atsuhiro Yorozuya, Yoshinori Takeuchi, Sachio Shintaku, Teppei Uno, and Takenori Yamashita ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)280 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The main purpose of river‐training works is flood control. Recently, the Ministry of Land, Infrastructure, Transport and Tourism (MLIT), Japan, has decided to incorporate environmental conservation to river training policies, which involves water quality, landscape, and diversity of wildlife habitats. To take those aspects into account, geological deformations by fluvial processes in river channels need to be simulated appropriately. However, it is still difficult to conduct river training works based on reliable predictions. This paper will introduce one of the examples of river‐training works and associated fluvial processes, which were unpredictable and brought about unwelcome consequences. Also, the paper described an aDcp‐based field survey and a resultant flow field. Finally, the authors will discuss the limitation of aDcp‐based measurements and the conventional data processing method, and propose an alternative method to elevate simulation accuracy.

Select this Article		Survey of Gravel Movement during Floods Using Low‐Frequency Communicator in the Tama River in Japan M. Fukushima and N. Hakoishi ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)281 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A gravel‐bar restoration project was started in 2001 in the Nagata District of the Tama River. As a part of the project, gravel augmentation was conducted as a trial in 2001 and the work is continuing. The objective was to increase the riverbed height and to maintain gravel‐bar area, but there were some concerns about the downstream region, such as local deposition of sediment which would reduce the discharge capacity. This paper reports on the following field study. First, a cross‐sectional survey was carried out to confirm whether gravel augmentation was effective for gravel‐bar restoration. Secondly, gravel movement was measured with a low‐frequency communicator to identify where imported gravel accumulates after a flood. From these observations, it was found that most of the imported gravel flowed downstream during a flood and tended to stop around the lower area of the Nagata District. However, local deposition of sediment was not observed downstream of the Nagata District.

Select this Article		Using Telemetry and a Fish Behavioral Model to Assess Fish Habitat Changes Caused by Alteration of River Morphology Masatoshi Denda, Kunihiko Amano, and Toshimasa Sugimo ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)282 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract In this study, we aimed to evaluate and compare the influence of the physical environmental characteristics of the Chikuma River on the biological community between 1893 and the present. The study was conducted on a floodplain in the middle reaches of the Chikuma River in Nagano Prefecture, central Japan. We reconstructed the past morphology of the Chikuma River from topographic survey results and hypsographic maps of the region around the river from 1893. Velocity distributions in 1893 were estimated from these recorded hydrologic parameters. Then, the behavioral patterns of virtual fish were simulated by the IBM on the basis of the reconstructed past velocity distribution. The flooded area differed between past and present regardless of the actual river discharge. In 1893, water overflowed the banks of the main channel during floods, creating a large flooded area. The simulated fish behaviors in 1893 differed from the fish behaviors recorded in 2003. The results for 1893 indicated that the fish occupied a large area where they can cruise. The fish sought refuge in low current velocity areas next to the river bank during floods. Once the fish found a low current velocity area, they did not move to another area until after the flood subsided. These results indicate that floodplain had important ecological function which supply refuges are for fish community and conservation and restoration flood plain in effective for river restoration.

back to top

DAM BREAK ANALYSIS: A COLLABORATIVE APPROACH

Select this Article		Hawaii Dam Break Analysis Follow‐On Actions Derrick Elfalan, P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)283 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract On March 14, 2006, during a severe storm event that impacted the Island of Kauai, the privately owned Kaloko Reservoir failed causing a flash flood that killed seven persons, blocked a major highway and destroyed at least two homes. As a result of this disaster, and to assure public safety, U.S. Senator Daniel K. Inouye secured $2 million in the FY 06 Emergency Supplemental Appropriation Act (Public Law 109‐234) for the creation of the Hawai'i Water Systems Technical Studies Program, Dam Break Analyses to help the State of Hawai'i Department of Land and Natural Resources (DLNR) Dam Safety Office conduct dam break studies for eleven selected dams. The State of Hawaii DLNR will use the findings from the dam‐break studies to work with dam owners, managers and emergency management organizations and conduct follow on actions. These actions include assessing hazard risk potentials, preparing and updating emergency action plans (EAPs), and continuing to develop emergency preparedness for such disaster scenarios.

Select this Article		Hawaii Technical Dam Break Studies: Hydraulic Studies and Dam Break Scenarios Martin J. Teal and Christopher Goodell ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)284 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract In the aftermath of the numerous severe storm events and the Kaloko Dam failure in February and March of 2006, Federal emergency appropriations were made. As one aspect of the Federal assistance, the Hawai'i Water Systems Technical Studies Program, Dam Break Analyses was created to help the State of Hawai'i Department of Land and Natural Resources (DLNR) Dam Safety Office conduct dam break studies. This paper focuses on the hydraulic modeling and dam failure aspects of the studies conducted for DLNR.

Select this Article		Hydrologic and Hydraulic Models for Performing Dam Break Studies Cameron T. Ackerman, P.E., Matthew J. Fleming, and Gary W. Brunner, P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)285 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The U.S. Army Corp of Engineers, in conjunction with the State of Hawaii, is evaluating the risks associated with potential failures of 11 Hawaii dams. An important question to be answered in any Dam safety study is “What will happen if the dam fails?” This question can be answered through the use of hydrologic and hydraulic computer models. The Hawaii Dam Break studies were performed by a team of federal, state, and consulting engineers. Very early in this study, it was decided that a consistent methodology would need to be used for all of the Dam Break analyses performed by the team. Part of the methodology was to use a specific set of computer models to perform the analyses. A Dam Break study consists of precipitation analyses; hydrologic modeling; dam breaching analysis; dam break floodwave routing; and inundation mapping of the resultant flood. Precipitation analyses were performed by utilizing Technical Paper Number 43, Rainfall‐Frequency Atlas of the Hawaiian Islands (NOAA, 1963); Rainfall Frequency study for Oahu (Giambelluca et al., 1984); and Hydro‐Meteorological Report 39, Probable Maximum Precipitation in the Hawaiian Islands (NOAA, 1963), in conjunction with several GIS tools and techniques. Hydrologic modeling was performed with the HEC‐HMS (Hydrologic Modeling System) software. Dam breaching analysis and routing of the resulting flood wave was performed with the HEC‐RAS (River Analysis System) software. In areas where one‐dimensional river hydraulics models were thought to be potentially inadequate, the two‐dimensional model FLOW‐2D was used for comparison of results. Inundation mapping of the resulting floods from various dam break scenarios was performed with the HEC‐GeoRAS software, an ArcGIS extension that processes HEC‐RAS model results. This paper discusses the use of HEC‐HMS, HEC‐GeoHMS, HEC‐RAS, HEC‐GeoRAS, and FLOW‐2D for performing the hydrology, hydraulics, and inundation mapping required for performing a dam break analysis.

Select this Article		Hydrologic Modeling for Dam Break Analyses in Hawai'i Robert MacArthur, P.E., Ph.D., Kevin Wong, P.E., and Todd Bennett, P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)286 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract This paper is one of several being presented during a special Technical Session dedicated to recently completed dam break and flood hazard mapping analyses that were performed throughout the State of Hawai'i on behalf of the State Department of Land and Natural Resources and the Honolulu District U.S. Army Corps of Engineers. Basin hydrology, dam break and downstream flooding assessments were conducted for eleven reservoirs located in the State of Hawai'i. This paper focuses on procedures used to develop consistent basin hydrologic information required for these studies. The overall hydrologic approach, data preparation and analysis; model parameter estimation; model testing, calibration and application methods; and key results are summarized, herein. When work began on the dam break studies in January 2007, there were very few hydrologic reports found that contained the hydrologic data, and types of detailed information required for the basins that were to be analyzed for this project. This paper provides a framework for developing hydrologic models designed to provide reliable rare storm event rainfall and runoff information in a variety of locations and settings throughout the State of Hawai'i. Hydrologic data needs are discussed along with sources where available data may reside. Discussions of methods used to develop information for ungaged basins (basins with no rainfall or runoff records) are presented along with methods used for developing and testing the hydrologic models, including hydrologic parameter estimating procedures. A summary of adopted hydrologic model parameter values and a discussion of lessons learned during the hydrologic modeling work are provided.

Select this Article		Introduction to the Conduct and Organization of the Hawaii Dam Break Studies Derek J. Chow, Denise M. Manuel, P.E., and Michael F. Wong, P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)287 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Beginning around February 20, 2006, the Hawaiian Islands experienced unusually severe rain showers that caused severe flooding throughout the State. On March 14, 2006, the privately‐owned Kaloko Dam on the island of Kauai failed sending a wall of water downstream that overtopped the Morita Dam, damaged Kuhio Highway, and swept away homes. At the request of the State of Hawaii, the Corps of Engineers' Honolulu District conducted emergency visual condition surveys of dams on the islands of Kauai, Maui, Oahu, Hawaii, and Molokai to determine if there were any immediate threats to public safety. These visual surveys resulted in point in time information on 143 dams. After touring the storm damaged areas on Kauai, particularly the damage caused by the Kaloko Dam failure, U.S. Senator Daniel K. Inouye requested emergency relief funds for Hawaii in the FY06 Emergency Supplemental Appropriation Bill that was being developed in the Senate at the time. The FY 06 Emergency Supplemental Appropriation Act (Public Law 109‐234) contained $2M for the Hawaii Water System Technical Studies program for the conduct of dam break analyses. The dam break analyses evaluated the downstream inundation area in the case of a dam failure below selected dams. The analyses did not establish when or the likelihood of a dam failure. The selected dams were identified by the State of Hawaii, Department of Land and Natural Resources Dam Safety Program Office. These analyses were conducted in coordination with other Federal agencies, emergency management agencies, and counties. The 11 dams studied are: Kauai (7) — Twin Reservoir, Waita Reservoir, Elua Reservoir, Aepo Reservoir, Puu Lua Reservoir, Halamanu Field 21 Reservoir, and Upper Kapahi Reservoir; Maui (1) — Reservoir 24; Oahu (2) — Nuuanu Dam and Wahiawa Dam; and Molokai (1) — Kualapuu Reservoir. The studies were conducted by staff from the Corps' Honolulu District, Corps' Hydrologic Engineer Center (HEC), and the A‐E firms of Parsons‐Brinkerhoff/Northwest Hydraulic Consultants, SSFM/WEST Consultants, Tetra Tech, and Oceanit Laboratories. This paper discusses the coordination by the Corps with the State of Hawaii Dam Safety Program Office, conduct of a model workshop, creation and function of the Technical Advisory Group, the production and review of multiple study products, and final transmittal of products for use by the State of Hawaii in coordination with dam owners and emergency management agencies.

Select this Article		Inundation Mapping of Dam Breach Conditions Justin M. Nodolf, P.E., Jay B. Smith, P.E., David L. Moore, and William T. Fullerton, P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)288 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The Hawaiian Islands experienced unusually severe rain showers in February 2006 that caused severe flooding throughout the State. On March 14, 2006, the privately‐owned Kaloko Dam on the island of Kauai failed sending a wall of water and debris downstream that overtopped the Morita Dam, damaged Kuhio Highway and swept away homes. As a result of this disaster, and to assure public safety, U.S. Senator Daniel K. Inouye secured $2 million in the FY 06 Emergency Supplemental Appropriation Act (Public Law 109‐234) for the conduct of dam break analyses. The State of Hawaii Department of Land and Natural Resources is the non‐cost sharing sponsor. The dam break analysis evaluates the extent of inundation for downstream areas that result from several unexpected dam failure scenarios. The analyses does not establish the likelihood of dam failures, but focus primarily on quantifying and mapping flood extents due to potential dam failures in order to prepare appropriate emergency action plans and provide better community awareness of these types of hazards. Eleven dams were studied as part of this State‐wide project, including Twin Reservoir, Waita Reservoir, Elua Reservoir, Aepo Reservoir, Puu Lua Reservoir, Halamanu Field 21 Reservoir, and Upper Kapahi Reservoir on the island of Kauai; Reservoir 24 on Maui; Nuuanu Dam and Wahiawa Dam on Oahu; and Kualapuu Reservoir on Molokai. There are four parts to each dam site evaluation study including: hydrology, hydraulic flood wave routing, inundation mapping, and reporting. This paper addresses the development of mapping to depict areas of inundation and flood risks downstream of each dam. The final dam site evaluation studies were completed in early 2008. These studies were performed by an integrated team of experts including local Corps staff, Corps' HEC, and AE firms of Tetra Tech, Oceanit Laboratories, SSFM/West Consultants, and PB Americas/Northwest Hydraulic Consultants.

back to top

BANK STABILITY

Select this Article		Cohesive Soil Erosion: Theory and Practice B. C. Utley and T. M. Wynn ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)289 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Considerable research has been conducted on the erosion of cohesive soils, yet predictive models remain rudimentary at best and few design data are available. This research summarizes the current knowledge on cohesive soil erosion. Cohesive soil erosion is a complex phenomenon, determined not only by soil properties and flow hydraulics, but also by the chemical interaction between the soil pore water and the eroding fluid. While noncohesive soils erode as individual grains, cohesive soils erode as aggregates; thus, interped bonding is also important. The erosion resistance of cohesive soils is further affected by changes in the amount and physical state of soil pore water: significant increases soil erodibility have been correlated to freeze‐thaw cycling. Considered a soil property, soil erodibility expresses the rate at which a soil will erode, once erosion starts. Typically, the erosion rate of cohesive soils is predicted using a model relating soil erodibility to a measure of the hydraulic forces on the soil. The most common expression is known as the excess shear stress equation, which states the erosion rate is proportional to the difference between the applied boundary shear stress and the soil critical shear stress. Originally used for noncohesive soils, the critical shear stress is defined as the hydraulic stress at which a soil will erode. For cohesive soils, critical shear stress is difficult to predict accurately; there is no precise definition of critical shear stress as there is rarely a defining the point at which erosion starts. Several researchers have developed empirical relationships between the critical shear stress of cohesive soils and soil properties, but the prediction of fluvial entrainment rates based on soil physical properties has had limited success. This lack of adequate methods to predict soil erodibility and critical shear stress for cohesive soils has led to the development of several field test methods using an impinging jet. Ongoing research is comparing these test methodologies.

Select this Article		Enhanced Application of Root‐Reinforcement Algorithms for Bank‐Stability Modeling Natasha Pollen Bankhead and Andrew Simon ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)290 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Sediment is one of the principal pollutants of surface waters of the United States and sediment eroded from streambank failures has been found to be the single largest contributor of suspended‐sediment to streams draining unstable systems in the mid‐continent. Riparian vegetation exerts mechanical and hydrologic controls on bank stability, with plant roots providing mechanical reinforcement to the soil matrix. Root reinforcement is largely a function of the strength of the roots crossing potential shear planes, and the number and diameter of such roots. Root densities vary in time and space and with species, and root tensile strength values have also been shown to vary by species. However, previous bank stability models have been constrained by limited field data pertaining to the architecture and extent of root networks within streambanks. In this paper, a method is developed to use previously published root‐architecture data, to derive parameters required for modeling. Results showed that changes in root numbers over time can be estimated using sigmoidal regressions, which commonly represent the growth rates of organisms. The Bank Stability and Toe Erosion Model (BSTEM) was used to simulate the effect of different root distributions, all approximating the same average root‐reinforcement over the top 1 m of the bank profile (5 kPa), but with differing vertical distributions (concentrated near surface, non‐linear decline with depth, uniform over top meter). The results of these runs showed that the assumed vertical distribution of roots in the top meter of soil was most important in those banks with heights less than or equal to 1 m.

Select this Article		Quantifying Existing and Potential Reductions in Sediment Loads from Streambanks Andrew Simon, Natasha Bankhead, Virginia Mahacek, and Eddy Langendoen ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)291 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Streambank erosion by mass‐failure processes represents an important form of channel adjustment and a significant source of sediment in disturbed streams. Little if any quantitative information is available on the effectiveness of bank treatments on reducing erosion. To evaluate existing streambank‐derived sediment loads and the potential reduction in sediment loadings emanating from streambanks afforded by remediation measures, the hydraulic and geotechnical processes responsible for mass failure were simulated under existing and remediated conditions using the Bank‐Stability and Toe‐Erosion Model (BSTEM) developed by the USDA‐ARS, National Sedimentation Laboratory. Two sites were selected from each of the three watersheds known to contribute the greatest amounts of streambank‐derived fine sediment in the Lake Tahoe Basin. The 1995 annual stage hydrographs supplemented by the large rain‐on‐snow event of January 1–2, 1997 were discretized into individual events to be used with surveyed channel slope data to calculate boundary shear stress for the toe‐erosion sub‐model. An excess shear‐stress approach was first utilized to simulate the extent of toe erosion. The updated geometry was then exported into the bank‐stability sub‐model to test for the relative stability of the bank under peak flow and drawdown conditions. In this way, BSTEM was used iteratively for all flow events for both existing conditions and with riprap toe protection. Volumes of material eroded by hydraulic and geotechnical processes were tracked for each event and summed to make comparisons between existing and remediated conditions. Under existing conditions, total streambank erosion by hydraulic and geotechnical processes ranged from 472 m³ to 5260 m³. On average, 13.6% of the material was eroded by hydraulic shear, the remainder by mass failures. Iterative simulations with 1.0 m‐high riprap toe protection showed a dramatic reduction in mean, total and fine‐grained streambank erosion (87%; std. error = 4.2%). Failure frequency for the simulation period was reduced in most cases to a single episode, which generally coincided with recession of the January 1–2, 1997 rain‐on‐snow event. Thus, an almost 90% reduction in streambank loads was realized by virtually eliminating the erosion of only 14% of the material that was entrained by hydraulic forces. As a consequence, average load reductions were about an order of magnitude. Results stress the critical importance of protecting the bank toe‐region from steepening by hydraulic forces. Iterative simulations using bank‐top vegetation showed about a 50% reduction in loads.

Select this Article		Seepage Erosion Mechanisms of Bank Collapse: Three‐Dimensional Seepage Particle Mobilization and Undercutting G. A. Fox, Ph.D., P.E., A. M. ASCE, M. L. Chu‐Agor, R. M. Cancienne, and G. V. Wilson, Ph.D. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)292 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Seepage flow initiates undercutting, similar to development and headward migration of internal gullies, by liquefaction of soil particles, followed by mass wasting of the bank. Although seepage erosion has three‐dimensional characteristics, two‐dimensional lysimeters have been used in previous research to analyze for the hydraulic and geotechnical controls on this mechanism of hillslope, gully, and bank instability. A 50 cm cubic soil block with a focused inflow reservoir was constructed to investigate the mechanisms of seepage erosion and the three‐dimensional nature of seepage undercutting. Experiments included 25‐cm tall, sand and loamy sand soil blocks packed at prescribed bulk densities (1.30 to 1.70 g cm⁻³) and with an outflow face at various angles (90, 75, and 60 degrees). Constant heads of 15 cm, 25 cm, and 35 cm were imposed on the soil to induce flow. A laser scanner was utilized to obtain the three‐dimensional coordinates of the bank and undercut surfaces at 15 to 30 s intervals. The bulk density for the two different soil types controlled which seepage failure mechanism occurred: (1) tension or “pop‐out” failures due to the seepage force exceeding the soil shear strength, or (2) particle entrainment in the seepage flow, particle mobilization, bank undercutting, and bank collapse when the seepage force gradient was initially less than the initial resistance force of the soil block. For cases experiencing particle mobilization and undercutting, seepage erosion initiated as unimodal (i.e., concentrated at one point) or as multimodal (i.e., initiating at several locations across the bank face), largely controlled by the bank angle. As a first approximation, a three‐dimensional, five‐parameter Gaussian distribution was fit to the undercut shapes to derive parameters for the maximum depth of undercutting, position of the center of the peak, and the vertical and lateral spreads of the undercut.

back to top

CONSTRUCTION AND IMPLEMENTATION OF RIVER RESTORATION PROJECTS

Select this Article		Application of a Deterministic Bank‐Stability Model to Design a Reach‐Scale Restoration Project Andrew Simon, David Derrick, Carlos Alonso, and Natasha Pollen‐Bankhead ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)293 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Sediment is one of the leading contributors to water‐quality impairment in the United States and streambank erosion has been found to be the dominant source of sediment in many watersheds with heightened sediment loads. Goodwin Creek is a typical incised channel in northeastern Mississippi (4.7 m‐deep) that yields about an order of magnitude more suspended sediment than stable, “reference” streams in the Mississippi Valley Loess Plains ecoregion. Periodic channel surveys in conjunction with dating of woody vegetation growing on the channel banks and bars in an actively eroding meander bend between 1977 and 1996 were used to determine an average migration rate of about 0.5 m/y over the period. Channel processes and sediment‐transport rates were monitored in detail between 1996 and 2006 and showed a similar migration rate. Because of continued land loss in adjacent agricultural fields by mass failure of the streambanks, a restoration project was designed to stabilize the banks and to protect a road running parallel to the bendway. Bank retreat occurs by interactions between hydraulic forces acting at the bed and bank toe and gravitational forces acting on in situ bank material. To provide a stable alternative, analysis of the restored configuration needed to address both hydraulic erosion and geotechnical stability. This was accomplished using a Bank‐Stability and Toe‐Erosion model developed at the USDA‐ARS National Sedimentation Laboratory. The proposed design was limited to 1:1 bank slopes due to the proximity of the road and included longitudinal stone‐toe protection and bendway weirs to counter basal erosion by hydraulic shear. Worst‐case geomorphic conditions under the proposed design were simulated by modeling (1) typical, annual high flows (3 m‐deep) to evaluate the amount of bank‐toe erosion that would occur, and (2) geotechnical stability where groundwater levels were high and flow had receded to low‐flow conditions in the channel (drawdown case). Results showed that the bank would still be unstable at 1:1 under the drawdown case but that the addition of specific riparian vegetation on the slope would stabilize the bank even under worst‐case conditions. The design was, therefore, implemented and constructed in a week.

Select this Article		Engineering Support during Construction of River and Wetland Restoration Projects: Case Studies for Optimization K. Price and M. Martz ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)294 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract River and wetland restoration projects differ widely in the optimal level of engineering support required during construction. Virtually all restoration projects benefit from some on‐site direction during construction; however, while some projects lend themselves well to “on‐the‐fly” design elements, other projects require much more detailed design plans and less variance from the designed placement of project features during construction. This paper discusses three restoration projects constructed in Oregon in the summer of 2007, each representing a differing project scale with varying levels of engineering involvement during construction. The projects are discussed in terms of their individual project features, including advantages and disadvantages of field‐directed changes by feature. The case studies support the conclusion that in river and wetland restoration projects, particularly those projects involving significant amounts of revegetation, field input during construction from both a biologist and engineer is highly beneficial to the project, so long as the allowance for variation is written into the contract documents.

Select this Article		Re‐Displacing a Heavily Modified Water Body to Its Aboriginal Course S. Lehmann and J. W. Lengricht ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)295 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract With regard to the end of the open lignite cast mining and the transformation of this landscape into ecologically and naturally shaped wetlands and river basins in Saxony, Germany the re‐displacement of a whole river section to its aboriginal state and course was investigated. The river Weiße Elster was heavily modified, the river bed was displaced and forced into a concrete channel to bypass the open coal mining area. A project of this matter self‐evidently falls within the realms of the European water framework directive as it covers suitably transformed ecological and hydromorphological conditions. The overall concept is demonstrated, the advantages and disadvantages are discussed in detail and the implemented approach to the specific area shall be illuminated from both point of views: the hydraulic one and the ecological one, i.e. biota, soils, groundwater, land use have to be taken into account as well as the hydraulic demands on a completely redesigned watercourse.

Select this Article		Transforming Floodplains into Ecological and Community Assets: Restoration of the Four Mile Run Corridor, Virginia Mark Tompkins, Cheri Salas, Daniel Medina, Tara Ajello, Laurens van der Tak, Anthony Falzone, Jeremy Thomas, Elliot Rhodeside, Bill Hicks, Jason Papacosma, and Claudia Hamblin‐Katnik ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)296 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The lower Four Mile Run corridor, 2.3 miles along the border of the City of Alexandria and Arlington County, Virginia, represents an untapped and largely forgotten resource. In spite of its lingering beauty, today's stream corridor functions largely as a flood control channel — an in‐between space defined by concrete banks, utility infrastructure and buildings that turn their backs to the stream. Yet, the two jurisdictions have begun to rediscover the potential of the Four Mile Run corridor as envisioned by community leaders who have sparked renewed energy and creativity into imagining the stream's glorious potential. The resulting Four Mile Run Restoration Master Plan represents a bold community‐based vision to revitalize the stream corridor, and to enhance the urban vitality of the communities along its shore, by improving its environmental, recreational, and open space resources. The master plan provides an overall blueprint for the transformation and identifies an initial demonstration project as well as the next steps in the implementation process. Community input was sought throughout the 14 month process. Public outreach included an extensive Visioning Event that brought over 150 people to a one‐day session during which groups collaborated on developing individual and shared visions for the future of the corridor and a series of Open House events that provided opportunities to review and respond to concepts as they were being developed. The plan was approved unanimously by both the Alexandria City Council and the Arlington County Board of Supervisors in 2006. The Four Mile Run Restoration Master Plan provides a planning and conceptual design framework for dramatically transforming the stream corridor in ways that reflect the project vision that was developed early in the planning process: Four Mile Run will become a model of urban ecological restoration. Through the sensitive and sustainable integration of natural areas with active urban nodes, the Four Mile Run corridor will be a place along which the communities of Arlington County and the City of Alexandria can gather, recreate, and celebrate a shared waterfront legacy. The core of the Plan is focused on maintaining and enhancing flood protection while, at the same time, restoring the natural stream processes and improving habitat within the corridor. The aesthetic, recreational, and urban life enhancements contained within the Plan are organized around the central principles of ecological restoration and enhanced flood protection. The Four Mile Run Restoration Master Plan is a model of inter‐jurisdictional and multidisciplinary collaboration. It illustrates the strength that communities, working together, can bring to developing a long‐term vision that focuses on environmental and community enhancement. A stream that once served to divide communities has now become a means of uniting and renewing them.

back to top

ECOLOGICAL RESPONSE: MODELING AND MANAGEMENT

Select this Article		A Comparative Study on Fish Physical Habitat Simulation Model Kukryul Oh, Sangman Jeong, JooHeon Lee, Hyeongdeok Seo, and Chanseong Park ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)297 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract In this study, PHABSIM which has a capability of 1‐Dimensional physical habitat modeling and River2D which has a capability of 2‐Dimensional physical habitat modeling has been applied to the major tributaries of Han River in order to estimate the optimum flow for the fish habitats and determine the instream flow. Moreover, the Weighted Usable Area (WUA) as well as optimum instream flow for fish habitat, estimated by the two different models in each growth step (adults and spawning) of the target fish had compared and reviewed. As a result, the correlation analysis for WUA between 1D and 2D models had estimated as the range of 0.87 to 0.99. The estimated optimum flow for each location considering the conditions of inhabiting fishes showed insignificant difference of 3 m³/s to 5 m³/s.

Select this Article		Connectivity in a Network‐Scale Model of Aquatic Population Dynamics A. Catherine Marcinkevage and E. E. Herricks ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)298 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract America's waterways face multiple pressures that have the capabilities to alter the hydrologic connectivity that maintains aquatic population persistence throughout the watershed. The dynamic feedback of organism response can provide a real‐time link between the habitat‐influencing hydrologic processes operating within a watershed and the ecological processes that shape aquatic communities. This paper describes the incorporation of a connectivity component into the habitat‐selection behavior of fish during high‐flow conditions. The research is part of a larger effort that focuses on the development and use of a spatially‐explicit individual‐based model (IBM) in evaluating the long‐term hydrologic effect of landscape change and management on aquatic communities. The model simulates the behavior of individual fish in their habitat selection process to analyze network dynamics in stream ecosystems in response to outside driving influences. The primary input to this model is streamflow and hydrologic connectivity related to watershed landscape characteristics. The results of this research show that connectivity does in fact contribute to the ability of aquatic communities to tolerate and recover from high‐stress conditions. However, despite the recognition of the importance of connectivity in watershed science, it has not been directly incorporated into models of large‐scale riverine systems. This work shows that connectivity, in addition to habitat quality, can influence species distribution within river reaches and affect population sustainability throughout the watershed area.

Select this Article		Flow Resistance Mechanism of Aquatic Macrophytes in a Simulated Channel Shiang‐Yuarn Chen and Jen‐Yang Lin ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)299 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The present study described in this paper was carried out in a simulated channel. The first part of the study examined how aquatic macrophytes respond to different channel flow velocities, in terms of changes in their flow resistance mechanisms, in order to confirm the suitability of local plants. The second part of the study examined the growth rate of the macrophytes, the growth rate and shape of macrophyte shoots, tissue strength of the shoots and roots, tolerance of the plants, and erosion‐resistance response at various velocities. Study results show that Oenanthe javanica (Blume) DC. (water celery) experienced morphological variations at different flow velocities. In particular, as flow velocity increased, growth rate slowed and plant shoots became shorter and softer, which increased plant flexibility. Root length and root anchorage decreased. In addition, root, stem, and shoot mass also decreased.

Select this Article		Steelhead Recovery in the San Juan and Trabuco Creeks Watershed Wendy Katagi, Theodore Johnson, P.E., and George Sutherland ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)300 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The San Juan Creek Watershed is a 176‐square mile catchment area which contains San Juan, Trabuco, and Oso Creeks. The lower reaches of San Juan and Trabuco Creeks have been degraded, while the upper reaches of San Juan and Trabuco Creeks and their tributaries remain fairly in tact. San Juan, Trabuco, nearby San Mateo, and San Onofre Creeks all had consistent steelhead runs up until at least the late 1940's (Hubb, 1946). The decline in steelhead is a result of: agriculture, mining, urban development, migration barriers such as the Trabuco Creek at Interstate 5 culvert, degraded stream habitat, decreased stream flow (e.g., withdrawals), and degraded water quality. California Southern Steelhead (Oncoryhnchus mykiss) were listed as an endangered species on August 18, 1997; the southern range was extended to the US/Mexico border on May 1, 2002, and endangered status was reaffirmed on January 5, 2006. It is important that the pristine condition of the upper watershed be preserved to facilitate steelhead recovery. Quality habitat needs to be preserved, and the spread of invasive plant and animal species needs to be controlled.

back to top

FLOODPLAINS AND FLOODWAYS

Select this Article		Functional Floodplain Assessment as an Environmental Performance Standard: Bridge Replacements in Oregon Mark A. Anderson ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)301 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Oregon (U.S.) implemented the $1.3 billion Oregon Transportation Investment Act (OTIA III) State Bridge Delivery Program to repair or replace over 300 bridges during 10 years. To meet the delivery schedule, alternative delivery mechanisms were developed including substantial use of design‐build project delivery, and programmatic environmental permits conditioned upon the Bridge Program's Comprehensive Mitigation and Conservation Strategy. One major aspect of the strategy is implementation of Environmental Performance Standards (EPS) for many aspects of the bridge design, including fluvial performance. The fluvial performance standard requires bridge design to “allow normative physical processes within the stream‐floodplain corridor.” Evaluating the channel processes requires calculations for bank full width and depth, flood prone width and depth, and entrenchment ratio. The result is a deterministic compliance test for adequate bridge length to allow geomorphologic stream processes. The case studies present three bridge replacement sites in Oregon. The studies describe the field and desktop methods used to collect necessary data for applying the fluvial performance standard. An evaluation is made of the controlling factors for bridge length, distinguishing between traditional “floodway process” considerations and the more recent “channel process” requirements. Conclusions are that the fluvial EPS is a beneficial method of screening bridge sites to minimize impacts on stream function. It is most useful for identifying grossly constrictive bridges where flood management historically has not been a significant issue. Refinement and definition is needed to balance the deterministic approach with the wide variety of site conditions encountered.

Select this Article		Restoration of Hydrologic Functions of Streams Impacted by Milldams Ward Oberholtzer and Arthur C. Parola, Jr. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)302 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Floodplain deposits upstream of milldams or other similar structures have affected the hydrologic function of eastern US stream channels. Stream restoration efforts that seek to restore channel profile stability and hydrologic function will require that both the channel and the floodplain be re‐constructed to establish a floodplain with a vegetation root zone and a channel bed that is hydraulically connected to the gravel aquifer. Depending on constraints limiting floodplain excavation, two approaches may be taken: full‐depth floodplain excavation and limited floodplain excavation. These techniques are based on the elevation of the gravel and bedrock that underlay the pre‐settlement floodplains and the aquifer that they support.

Select this Article		Storing Sediment in a Coastal Plain Valley Plug: Obion Creek Stream Restoration Arthur C. Parola, Jr., Michael A. Croasdaile, Ward Oberholtzer, and William S. Vesely ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)303 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A primary assumption in the design of stream restorations is that the sediment supplied to the restoration reach should be transported out of the restoration reach. In watersheds that have been disturbed by human activity, however, the supply gravel and sand that form bedload‐material load can be excessive, necessitating that the channel be designed to produce high boundary stresses sufficient to maintain transport. A more practical approach to restoration design would be the gross management of coarse and fine‐grained sediments through either removal of the excess sediment sources or storage of the supplied sediment. This sediment management concept was employed in the restoration design for Obion Creek, located in the western Kentucky region of the Coastal Plain. Channelization of most streams in the Obion Creek watershed led to severe channel incision in most tributaries and aggradation of the Obion Creek channel bed at other locations. Upstream channels had incised, mobilizing the loess, sand, and gravel that composed the surrounding hills. The channelized reach eventually filled with sediment and debris, forcing water to flow overland in heavily braided patterns for nearly two miles before entering a recognizably active silt‐bed channel. This existing valley plug was incorporated into the restoration design, allowing the channel to accumulate gravel and coarse sand and to splay fine sand and silt on a wide floodplain. To transport silt to the downstream channel, historic channels capable of transporting only silt were connected to the restored channel and reactivated. In the case of Obion Creek, prior modifications of the channel network and changes in hydrology had caused changes in the sediment regime. By incorporating sediment storage into the design, the restoration was able to manage the load while still supplying enough silt to maintain the downstream channel.

Select this Article		The Dallas Trinity Lakes Project: Challenges and Approaches to Designing a Channel Realignment Scheme to Satisfy Multiple Objectives Mark R. Tompkins, P.E., Ph.D., Greg Ajemian, P.E., Gregory Welch, P.E., Anthony Falzone, and Jeffrey J. Barry, Ph.D. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)304 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The Trinity River in Dallas (drainage area of 6,100 square miles at Dallas) has experienced dramatic change over the past century, with the most rapid and extensive changes occurring during the construction of the original Dallas Floodway project in the late‐1920s and the US Army Corps of Engineers (USACE) reconstruction of the floodway in the mid‐1950s. The City of Dallas is currently designing the Trinity Lakes Project based on the objectives and conceptual design developed in the Balanced Vision Plan (BVP) for the Trinity River Corridor (City of Dallas 2003). The project includes significant physical changes to the channel and floodway including restoration of channel meanders, creation of a mid‐channel island or oxbow lake, alterations to channel geometry, and construction of two lakes in the floodway adjacent to the channel. One of the key success criteria for this project is the creation of a realigned channel with enhanced aesthetic, recreational, and habitat features that are sustainable through time and in relation to other features of the project in the floodway. Given the dynamic nature typical of alluvial river channels such as the Trinity, achieving this criterion poses significant challenges during the design process. The purpose of this paper is to summarize hydrologic and geomorphic assessments conducted to document and quantify historical and ongoing channel and floodway change. In addition, we present a design process that combines these historical analyses with approaches from landscape architecture and state‐of‐the art hydraulic and sediment transport modeling to translate the Balanced Vision for the Trinity Lakes project into the most sustainable detailed design possible for the site.

back to top

INTEGRATED WATERSHED MANAGEMENT

Select this Article		Integrated Catchment Management Planning in Auckland, New Zealand — Experiences and Lessons Learned C. Hellberg, H. R. Easton, and M. D. Davis ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)305 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Stormwater is recognised as having the largest impact on the Auckland region's freshwater and marine ecosystems with flow‐on adverse impacts on the social, cultural and economic values of the regional community. Furthermore, one of Auckland's greatest challenges is to enable growth to occur in the region while maintaining and enhancing the quality of life and the environment. Since 2004, the Auckland Regional Council (ARC), through the Stormwater Action Plan, have provided contributory funding assistance (i.e. subsidies) to Territorial Authorities (local government) to prepare Integrated Catchment Management Plans (ICMP's) that follow an ICMP Funding Guideline. A review of ICMP's prepared to date has identified several challenges to achieve outcomes intended from the contributory funding assistance: (1) The potential benefits of ICMP's are not fully recognised within most Territorial Authorities, (2) ICMP's are best developed as planning tools and (3) many Territorial Authorities do not fully recognise that ICMP's are planning tools developed and owned by the Territorial Authorities. As a result of the review, it was proposed to amend the ICMP Funding Guideline to clarify the philosophy, scope and purpose of ICMP's, and to more clearly reflect the original purpose of the contributory funding assistance as stated in the Stormwater Action Plan. A critical first step in this review process was to ensure that there is a good understanding and acceptance within the ARC to amend the ICMP Funding Guideline. The subsequent step was to approach the Territorial Authorities for their input. The final step, after promoting awareness, is to improve the process of ICMP preparation, particularly clarification of technical components within the ICMP funding guideline, which the ARC has acknowledged is due to the limited direction provided in some instances. The ARC's current strategy is to improve the preparation and implementation of ICMP's based on five ‘legs’: Awareness, Improvement, Guideline, Education, and Future.

Select this Article		Integrated Water Resources Management in Uganda: Past, Present, and a Vision for the Future Mark Henry Rubarenzya, Ph.D., M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)306 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract This paper presents the evolution of Integrated Water Resources Management (IWRM) in Uganda. It presents practical experiences of the opportunities and constraints to the implementation of IWRM. The institutional management of water is presented including a review of relevant policies, the legislative framework, and the national structure for the management of water resources. While Uganda is well endowed with significant freshwater resources, the challenges of rapid population growth, increased urbanization and industrialization, uncontrolled environmental degradation and pollution are leading to accelerated depletion and degradation of the available water resources. To meet the above challenges, the government of Uganda (GOU) instituted reforms in the water sector to ensure that water services are provided and managed with increased efficiency and cost effectiveness. These reforms and the changes towards IWRM are discussed in the paper. Limitations and opportunities are identified. The paper presents a vision for the future towards truly Integrated Water Resources Management. This includes the Sector Wide Approach to Planning; the vision for management at catchment or basin scale; cross‐sectoral undertakings to develop trust, increased information dissemination; and the adoption of management tools and modeling techniques in IWRM.

Select this Article		The California Water Crisis Oak Glen Creek Detention Basins, Yucaipa, California “An Integrated Approach to Watershed Management” Jeffrey K. Rupp ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)307 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The three basins are designed to capture storm water in both large and small events and allow storm water infiltration into the groundwater basin and “recharge” the groundwater table. The DEA team designed the project to save some existing oak trees, while areas that were being disturbed are being planted with native materials. By planting native materials, maintenance will be minimized and habitat for wildlife will be provided. The project will include a small parking lot, recreational trails, “outdoor classrooms”, educational kiosks, and scenic outlooks. The educational kiosks and signage will provide information on the “water cycle” and will help people to understand the importance of water in our environment while also educating them on how to clean up, conserve, and recycle water. The Oak Glen Creek Detention Basin Project provides an integrated approach to watershed management. By capturing storm water and allowing groundwater infiltration we can reduce downstream flooding, improve water quality, recharge the groundwater supply, and provide open space for wildlife and plant life. Allowing people to access the facility provides an opportunity to educate people on the importance of the water cycle and encourage people to set aside open space for drainage facilities in lieu of more concrete channels.

back to top

LARGE‐SCALE WETLAND/MARSH RESTORATION

Select this Article		Implementing Everglades Restoration Using Incremental Adaptive Restoration Stuart J. Appelbaum, M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)308 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A comprehensive plan to restore the greater Everglades ecosystem was approved by Congress in the Water Resources Development Act of 2000. The Water Resources Development Act of 2000 also requires that an independent scientific review panel be established to review the comprehensive plan's progress towards achieving the natural system goals of the plan and to produce a biennial report to Congress. The Corps of Engineers has contracted with the National Academy of Sciences to conduct this independent scientific review. The first report of this review panel was completed in September 2006. The panel found that much good science has been developed, but that restoration progress in key areas in the Everglades has lagged progress made in other areas of the south Florida ecosystem. They found that one of the reasons for the delays is a project planning process that can be stalled by unresolved scientific uncertainties. The Committee recommended consideration of a new approach, termed Incremental Adaptive Restoration, by the Corps of Engineers and its implementation partners. Incremental Adaptive Restoration involves making investments in restoration that are significant enough to secure environmental benefits while also resolving important scientific uncertainties about how the natural system will respond to management actions. Adopting the Incremental Adaptive Restoration approach involves a fundamental change in how the comprehensive plan is implemented. Consequently, the Corps of Engineers and its partners are now developing a new sequencing plan to incorporate the Incremental Adaptive Restoration concept. This new sequencing plan is intended to sequence and schedule projects to support Incremental Adaptive Restoration with a focus on goals, results expected, and specific learning objectives expected to resolve uncertainties. The existing project authorization and budgeting process for comprehensive plan projects may need to be revised to fully implement the Incremental Adaptive Restoration process.

Select this Article		Integrated Hydrologic and Hydraulic Modeling for the Restoration of the Calumet Marshes in the Great Lakes Area Yanqing Lian, Ph.D., Mohamad Hejazi, George Roadcap, Ph.D., and Ximing Cai, Ph.D. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)309 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Lake Calumet is located south of Lake Michigan in the United States. It is a site of former landfills and abandoned industrial facilities, yet a place of economical and ecological significance for future development of the area. Marshes surrounding Lake Calumet are ecologically significant to the Black‐crowned Night‐Heron, but the hydrology in the area has been greatly impacted by the large amount of landfilling and the constantly changing land use and drainage of the surrounding uplands. To prevent ecosystem degradation, and recreate a local economic base, the City of Chicago Department of Environment has been leading community groups and other agencies to develop plans to restore the region to a recreational area. Millions of dollars will be invested for this effort. Hydrologic and hydraulic models have been developed to support the plan for an ecological park in the region. These models serve as a basis for determining the best water management strategies for the Lake Calumet cluster site and adjacent open spaces, known as Indian Ridge Marsh (IRM). The coupled hydrologic and hydraulic model was used to evaluate the hydrologic impacts of different remedial options proposed for the cluster site, as well as other upland properties in the marsh watersheds and to assess the adequacy of the existing marsh outlets in terms of long‐range ecological goals. This paper evaluates five proposed management scenarios to cope with flooding and to establish a more suitable environment for Black‐crowned Night‐Heron nests in marsh areas by controlling water level fluctuations. Our study showed that diverting surface runoff from the cluster site appeared to be the best option for limiting water level fluctuations to around 8 inches in the IRM. Ten inches of fluctuation is the maximum to prevent flooding of Black‐crowned Night‐Heron nests in IRM.

Select this Article		Kawainui Marsh Wetland Restoration Travis W. Hylton, P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)310 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The Honolulu District of the U.S. Army Corps of Engineers (USACE), in cooperation with the Hawaii State Department of Land and Natural Resources (DLNR), Division of Forestry and Wildlife (DOFAW), has authorized and funded the design the Kawainui Marsh Restoration Project (KMRP). Kawai Nui Marsh is the largest remaining wetland in Hawaii, encompassing approximately 830 acres of land in Kailua, Oahu. The marsh provides important habitat for four endangered species of native Hawaiian waterbirds and for migratory bird species, and is identified by the U.S. Fish and Wildlife Service as a waterbird recovery area. The project purpose is to restore approximately 40 acres of the upper portions of the Kawainui Marsh to habitat suitable for endangered Hawaiian waterfowl; namely the Hawaiian Duck (Hawaiian name: Koloa, Scientific name: Anas wyvilliana), Hawaiian Stilt (Hawaiian name: Aeo, Scientific name: Himantopus mexicanus knudseni), Hawaiian Moorhen (Hawaiian name: Alae ula, Scientific name: Gallinula chloropus sandviceensis), and Hawaiian Coot (Hawaiian name: Alae keo keo, Scientific name: Fulica Americana alai).

back to top

POSTER SESSION VI: WATERSHED RESTORATION

Select this Article		Identifying the Cause of Stream Impacts — The West Fork Case Study Scott E. Sonnenberg, P.E., M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)311 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The West Fork of the East Branch of the Black River, outside of Lodi, Ohio, was experiencing increased sediments within the river during moderate to high flows, which was of concern to the Medina County Park District and other land owners along an 8000 If stretch of river just south of Highway 224. Local landowners commented about increased velocities, frequency of flooding, and rates of bank erosion. Field investigations, maps and aerial photos indicated a moderately sinuous “C” type channel with gravel riffles and bars and silty sands in pools. The 40 square mile drainage area consists mostly of farm fields and undeveloped wooded areas with a small commercial/industrial area on the west side of Lodi. A 1 to 2 year flow rate of 430 cfs resulted in a bankfull depth of about 4 feet, width of 50 to 60 feet and a velocity of 2–3 f/s, which was consistent with field observations of gravel bars and vegetation. The existing eroding bank heights were not consistant with this data though. They varied from 5 to 6 feet at the upstream end and 10 to 12 feet at the downstream end. Initial conclusions were that much of the floodplain vegetaion had been cleared and farming operations had deposited significant sediment onto the floodplain raising elevations as much as 4 to 5 feet. The valley side slopes also narrowed which may have contributed to the rising floodplain to stream bed difference. But some observations, such as 100+ year old trees along the stream bank and soil cross sections not showing significant deposition, indicated something else. Then we found the 1937 aerial photographs, used for creation of the Medina County Soil Survey, for the area now crossed by Highway 224 and our whole perspective regarding man's impact on this river changed along with our recommendations for mitigation.

Select this Article		Ecological Co‐Conservation and Sharing Mechanism for Sustainable Watershed Management Benqing Ruan, Fengran Xu, Yulong Liu, and Chunling Zhang ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)312 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract It is necessary to promote the harmony between human and nature, and the equity between upstream and downstream areas for river basin sustainable development. Ecological compensation is being applied to pay for ecological services and transboundary external effects caused by ecological conservation or exploitation in China. A conception of co‐conservation and sharing, which means to burden the conservation cost and share the benefit in the whole river basin, is presented in this paper to solve the difficulties with current research and implementation of ecological compensation in China. The scale of co‐conservation area is determined by geographical characteristics, while the sharing area is established depending on economic factors. Xin'an River Basin, related to two provinces in East China, is taken as the study area. The territorial scales of the co‐conservation area and the benefit sharing area are determined. By analyzing the transformation of environmental protection costs and benefits between different districts and sections, the distribution of conservation costs is conducted in the whole sharing area. Furthermore, a framework for co‐conservation and sharing mechanism is discussed.

Select this Article		Restoration of Military Training Lands: Development of Decision Support Tools William E. Fox, Dennis W. Hoffman, Tom J. Gerik, Jimmy R. Williams, and Susan Wang ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)313 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Sustainable management of military training lands is critical to the ongoing mission of preparing U.S. military forces to fight and win wars. Development of next generation biophysical and economic models for planning and assessment of military land restoration programs can provide a vital decision support tool for military land managers worldwide. Providing accurate decision support for determining appropriate best management practice (BMP) selection based on available knowledge is critical and can provide accountability for restoration funding. Utilizing a multitude of data including hydrologic, vegetation, soils and erosion data from the U.S. Army's Fort Hood military installation, a team of scientists is working to parameterize the Agricultural Policy extender (APEX) simulation model's capabilities for application on highly disturbed military training lands. Development on lands under such harsh disturbance regimes will provide a robust technology that can be easily adapted to rangeland and other ecosystems under less stressful disturbance conditions. Results of preliminary model parameterizations indicate potential benefits in the development and application of hydrologic models to address erosion reduction practices utilized on Fort Hood.

Select this Article		Will Large Scale Forest Restoration Treatments Provide More Water for Population Growth in the Semi‐Arid West: Current Hydrologic Research in Arizona Boris Poff and Daniel G. Neary ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)314 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Ponderosa pine forests in the western United States are undergoing restoration treatments in form of tree harvesting and prescribed fire on an unprecedented scale to reduce the risk of catastrophic, stand replacing wildfires, especially in the Wildland‐Urban Interface (WUI). National Forests within the ponderosa pine region of the Interior West are realizing early on in their NEPA analysis process for fuels treatments that there is a gap in watershed response data. In past forest watershed research, fuel treatments, specifically thinning in combination with prescribed fire, were never properly evaluated by watershed‐scale research studies. The Mogollon Rim Ranger District, Coconino National Forest, Arizona, determined in its planning process that it needed to obtain watershed response information, namely watershed yield, peak flows, as well as soil and vegetative responses on a watershed scale, in order to prepare adequate NEPA documents for future fuels treatments. The District's plan to implement a fuels reduction project both within and outside of the WUI within the Beaver Creek Experimental Watershed presented a unique opportunity to expand upon existing knowledge, and fill in critical treatment‐effects information gaps. This effort will help not only the Mogollon Rim Ranger District, but also other National Forests in the Arizona ponderosa pine region as well as land and fire managers throughout the southwest. The study utilizes the existing watersheds of the Beaver Creek Experimental Watersheds south of Flagstaff, Arizona. Five watersheds (between 76 and 722 ha) were reinstrumented with new stream gages in 2006. The restoration treatments planned by the Coconino National Forest include varying combinations of mechanical thinning and prescribed burning. This paper describes the research and monitoring efforts conducted for this.

back to top

RIGID STRUCTURES/CHANNEL ROUGHNESS

Select this Article		Calibration of a Two‐Dimensional Hydrodynamic Model for Simulating Flow around Partially Submerged Structures B. G. Wardman and A. N. Papanicolaou ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)315 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The objective of this paper is to calibrate a depth‐averaged two‐dimensional hydrodynamic model for simulating flows over and around partially submerged structures. The model calibration is part of a larger case study using the two‐dimensional model FESWMS to predict the effectiveness of a bendway weir design at mitigating bank erosion on a mild‐gradient sand bed river. The calibration is based on flow measurements observed around constructed bendway weirs using Large Scale Particle Image Velocimetry (LSPIV), Acoustic Doppler Velocimetry (ADV), and sonar. The two part methodology used in the calibration produced simulation results consistent with both the measured data as well as other findings reported in literature. Results from the study show that a depth‐averaged parabolic eddy viscosity and increased bed shear values are ideal for matching the reach scale flow properties. However, accurate representation of the flow processes occurring near the structure required refined material properties with minimal bed roughness values. These findings compare favorably with other reported studies and are discussed in depth.

Select this Article		Modeling the Long‐Term Impacts of Using Rigid Structures in Stream Channel Restoration Sue L. Niezgoda, Ph.D., P.E., A. M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)316 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Natural channel designs often incorporate rigid in‐stream structures to protect channel banks, provide grade control, promote flow deflection, or otherwise improve channel stability. The long‐term impact of rigid structures on natural stream processes is relatively unknown. The objective of this study was to use long‐term alluvial channel modeling to evaluate the effect of rigid structures on channel processes and assess current and future stream channel stability. The study was conducted on Oliver Run, a small stream in Pennsylvania relocated due to highway construction. Field data was collected along the 107 m reach to characterize the stream and provide model input, calibration, and verification data. FLUVIAL‐12 was used to evaluate the long‐term impacts of rigid structures on natural channel adjustment, overall channel stability, and changing form and processes. Results indicated that the presence of rigid structures reduced channel width‐to‐depth ratios, minimized bed elevation changes due to short‐term local scour and fill and long‐term aggradation and degradation, limited lateral channel migration, promoted pool filling, and increased the mean bed material particle size throughout the reach. Results also showed how alluvial channel modeling can be used to improve the stream restoration design effort.

Select this Article		Restoration of Gravel Bed Rivers via the Use of Stone Clasts (Rocks) D. C. Dermisis and A. N. (Thanos) Papanicolaou ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)317 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Different studies have examined the transport of fine sediments over and within gravel beds. Comparatively little attention has been given on how distinguishable isolated roughness elements, such as clasts (rocks or boulders), may affect the movement of sand over and within gravel substrates. Rocks have been widely used for stream restoration purposes. Previous research focused primarily on the effects that rocks have on the flow structures in their vicinity neglecting possible effects on sediment depositional patterns. The overarching objective of this study is to examine experimentally the twofold effect of the presence of clasts on the movement of sand over and within a gravel bed. Specifically, this study will provide: 1) an improved understanding of the linkage between the mean flow characteristics and the sediment depositional patterns; 2) an analysis on the frictional characteristics around the clasts; and 3) a quantitative description of the sediment deposition within the substrate as it relates to fish survival.

Select this Article		Science Based Restoration to Describe Bed Microroughness in Gravel Streams A. G. Tsakiris and A. N. (Thanos) Papanicolaou ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)318 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The objective of this research is to investigate the geometrical properties, and in particular the shape, of ubiquitous bed patches in gravel streams known as clusters. The inherent irregularity that clusters have, prevents their description with the traditional methods. Clusters come in different shapes, viz. line‐clusters, rhomboid, triangular and are the outcome of bed reworking by the flow. Thus, we employ the fractal geometry, which uses the fractal dimension, D, for the study of the clusters. The box counting method is used for the D estimation of clusters created artificially and under laboratory conditions. The results of the study demonstrate the potential of D to quantitatively characterize the different cluster shapes and classify them in shape categories. This finding shows that the proposed technique may be used for field pattern recognition and characterization of microroughness in gravel streams. The latter is of paramount importance to modellers as well as for simulating flows over ubiquitous gravel roughness elements, such as cluster microforms.

back to top

RIVER MODELS

Select this Article		A New Formulation of the Distributed Rainfall‐Runoff Model Using Object‐Oriented Modeling M. Okabe, S. Kure, and T. Yamada ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)319 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Today, many kinds of rainfall‐runoff model have been proposed. Those models' calculations are executed by binding hydrological elementary steps of the whole basin represented as various methods or models. As a prerequisite for using such programs, understanding specialized knowledge such as hydrology or hydraulics is needed. If user wants to add or extend the model, the programming knowledge is also required. The problem for using such program is that the user is not always experts in those fields. For example, not every water administration officials are capable as professional engineers. The purpose of this study is to formulate universal and easy incorporable integrated flood forecasting model. In this instance we are proposing the new distributed rainfall‐runoff model using circuit diagram as a runoff model.

Select this Article		Digital Mapping of Waterway Hydrodynamics, Banks and Floodplain Using Imagery A. Hauet, M. Muste, and H.‐C. Ho ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)320 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Sound scientific understanding of the river hydro‐geomorphological changes requires good measurements of the dynamics between the interacting river components over time scales commensurate with their interaction. While great progress has been made for quantifying this interaction, there are still considerable measurement limitations to simultaneously acquire information about the river water body and the adjacent banks and flood plains. We propose a new, innovative method that easily quantifies and documents waterway features in the vicinity of bridges using photo imagery. This method combines concepts of image processing and image velocimetry to provide quantitative information on the floodplain topography and texture, as well as of the river hydrodynamics at obstructed and un‐obstructed waterways sites. Images are collected by photographing bridge surroundings. Customized software provides means of assembling these photos in a composite distortion‐free panoramic image that can be stored in electronic format. Large‐scale Particle Image Velocimetry techniques are used to measure the free‐surface velocity of the waterway. The proposed tool facilitates routine bridge inspections, bank erosion studies, and provides quantitative information for a variety of geomorphic and hydraulic waterway parameters.

Select this Article		RiverGages.com: One Door to the Corps for USACE Water Management Christopher M. Trefry, P.E., M. ASCE, Richard T. Engstrom, P.E., and S. K. Nanda, P.E., F. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)321 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Beginning in the early 1990's, individual U.S. Army Corps of Engineers (Corps) Water Management offices began implementing internet tools for display of stream, reservoir, and navigation structure data. In 2002, it was decided by the Corps' Mississippi Valley Division (MVD) to develop a common access point for all water management information within the Division. A Configuration and Control Board was established with one member from each office in MVD to develop a single web‐site that would serve water management information to both internal and public customers in a consistent and easy to use form. The product of this collaborative effort is RiverGages.com. Because of its data acquisition system and data storage flexibility, RiverGages has expanded beyond the Mississippi Valley and is poised to become the national web‐site for Corps Water Management. The past, present, and future of RiverGages will be discussed, along with its unique features which have brought it to the forefront of Corps Water Management.

Select this Article		Watershed Models for Stormwater Management: A Review for Better Selection and Application Deva K. Borah, M. ASCE and Jamie H. Weist, M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)322 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Many watershed models are available today and those are diverse with various complexities, strengths, and weaknesses. The objective is to review available watershed models for stormwater management and provide useful information and understanding of those for the end users, particularly the managers, so that an informed decision in selecting a model suitable for an application can be derived. Twenty one watershed models simulating storm event runoff including sediment and chemicals were reviewed and evaluated resulting in the development of four matrices: (1) model summaries, (2) model complexities, (3) relative accuracies, and (4) ease of model use. Emphasis was placed on theoretical bases, sophistication levels, and relative accuracies. The evaluations documented in the matrices are informative and useful to the managers, however, should be considered qualitative and only used in preliminary screening.

back to top

RIVER RESTORATION DESIGN STANDARDS/CRITERIA

Select this Article		Comparison of Empirical and Analytical Physical Assessment Approaches for Stream Restoration: A Case Study on Abrams Creek, Great Smoky Mountains National Park, Tennessee John S. Schwartz, Daniel L. Carter, Eddy J. Langendoen, and Andrew Simon ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)323 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A physical assessment approach referred to as natural channel design (NCD) is commonly used today by stream restoration practitioners, which requires an empirical‐based comparison between study and reference reaches. Use of available analytical tools, or models, into pre‐design physical assessments is not widely applied, an approach that does not require a reference condition. As a case study, a comparison of empirical and analytical approaches was conducted on Abrams Creek, located in the Great Smoky Mountains National Park (GRSM), Tennessee. Historically, the Abrams Creek valley was used for subsistence agriculture beginning in the 19^th century, and cattle grazing more recently between the 1930's and 1960's. Several tributaries and a few mainstem sections were channelized for agricultural purposes. GRSM resource managers requested that a channel stability assessment be conducted to evaluate whether restoration was needed because a consulting group was promoting a project on Abrams Creek in order to obtain mitigation credits. This study provided an opportunity to compare geomorphic data input/outputs used in NCD and analytical approaches. The NCD approach utilized stream classification and various geomorphic channel attributes at “bankfull” for a departure‐type analysis. The analytical approach utilized HEC‐RAS and CONCEPTS models. Supporting these approaches, assessment of channel condition also included: aerial photo interpretation, rapid geomorphic assessments for stability indices, and longitudinal profile knickpoint analysis. Some of the findings included: 1) bankfull flow was greatly overestimated by the empirical approach, whereas HEC‐RAS with a hydrological analysis provided a more reasonable estimate, 2) a departure analysis found that C4 study and reference reaches were similar for most geomorphic attributes, except for channel slope and bank material, which made restoration needs difficult to discern, and 3) CONCEPTS provided useful information on bed aggradation/degradation and bank failure rates, whereas the NCD approach could not. hi addition, similarities and differences of data input needs, and where professional judgment influences assessment outcomes were identified to better understand uncertainties associated with outcomes for both assessment approaches.

Select this Article		Developing a Standard of Practice by Organizing Goals/Objectives, Multidisciplinary Investigations and Design Criteria into a Process for Design: An Example Greg Koonce ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)324 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Designing and implementing stream habitat improvement techniques is a current field of engineering/landscape architecture that has no generally agreed upon standards of practice. Therefore, many different approaches are used, some analytical and others experienced based. This variation in approach often leads to confusion within professions and prevents adequate review of both completed and proposed designs and projects. This is further complicated as many practitioners believe that design is as much art as science. Professional practice standards define decision‐making procedures/methods used by practitioners and establish the basis for rational design development. This paper highlights a process whereby the development of goals and objectives, investigations of specialty disciplines (hydrology, geomorphology, hydraulics, fisheries, etc.) followed by the development of design criteria prioritized by goals/objectives, provide a basis for a standard of practice. A stream improvement example serves to illustrate key points.

Select this Article		Effective Measures of “Effective Discharge” Lauren Klonsky and Richard M. Vogel ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)325 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The concept of effective discharge, Q_e, introduced by Wolman and Miller in 1960 is that streamflow which transports the most sediment over time. Recently, numerous investigators have questioned how meaningful Q_e is as a descriptor of sediment transport and new discharge indices, such as the half‐load discharge Q_1/2, have been introduced to improve the precision with which one describes the ability of a particular discharge to transport sediment. Numerous recent studies have also suggested that among the various empirical estimators of Q_e, there does not seem to be a uniform consensus as to which is most consistent and meaningful. This study uses an example to clarify the method of estimation of both Q_e and Q_1/2. We show that the discharges up to the effective discharge for the Mississippi River at St Louis, are only responsible for carrying 25% of its long term sediment load. We question whether or not such a discharge is truly “effective” in terms of its ability to transport sediment, over time. An alternative index, the half load discharge, is recommended instead, because it is always responsible for transporting 50% of the long term sediment load.

back to top

STORMWATER BMP EFFECTIVENESS

Select this Article		Seasonal Variations in Net Methyl Mercury Production and Total Mercury Removal in a Constructed Wetland Prithviraj V. Chavan, Keith E. Dennett, Mae Sexauer Gustin, and Eric A. Marchand ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)326 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Ten parallel wetland mesocosms with four replicate experimental designs were utilized to assess seasonal variation in total mercury (THg) removal and net methyl mercury (MeHg). Experimental designs included 1) Hg contaminated water and sediments (MW‐MS), 2) Hg contaminated water and clean sediments (MW‐CS), 3) clean water and Hg contaminated sediments (CW‐MS), and 4) clean water and sediments (CW‐CS). No seasonal variation in THg removal was observed for any experimental design. The designs receiving Hg contaminated water were sinks for THg with average removal of 59±29%. In contrast, designs receiving clean water were least effective in THg removal (18±34%). Seasonal variation in MeHg production was observed for designs MW‐MS and CW‐MS, with values peaking in the late spring and summer, whereas, other designs did not show seasonal variation. Sulfate and temperature were most important parameters found to drive MeHg.

Select this Article		Statistical Evaluation of BMP Effectiveness in Reducing Fecal Coliform Impairment in Mermentau River Basin Z.‐Q. Deng and H. Chowdhary ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)327 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract This paper presents a statistical method for determining pathogen sources and for evaluating the effectiveness of conventional Best Management Practices (BMPs) in reducing fecal coliform bacterial impairment using water quality data monitored from 1980 – 2006 in the Mermentau River Basin. The statistical method mainly involves (1) determination of seasonal variations in the mean of flow and fecal coliform count in order to identify critical months of pathogen pollution, (2) establishment of multiple correlations between fecal coliform count and rainfall and other solid or sediment‐related water quality parameters, (3) detection of temporal variation trends in the median of fecal coliform count in different watersheds within the basin, and (4) evaluation of the effectiveness of BMPs in reducing fecal coliform bacterial impairment based on the trend analysis and water quality criteria. Results of the statistical evaluation show that (1) February – May are the critical months of the highest fecal coliform count; (2) The main pollution in February – March is caused by wet weather runoff; (3) The severe pollution in April and May is related to the releases of muddy rice_field water; (4) Since the implementation of BMPs in 1990, water quality in most watersheds in the Mermentau River Basin has shown an improving trend in terms of fecal coliform count while it was worsening from 1980 – 1990. In terms of pathogen impairment the most polluted areas in the basin are the two watersheds Bayou Queue de Tortue and Bayou Plaquemine Brule, followed by the Bayou Nezpique watershed; and (5) BMPs need to be enhanced in the basin to meet water quality standards.

Select this Article		Targeting vs. Optimization: Critical Evaluation of BMP Implementation Plan for Watershed Management Indrajeet Chaubey, C. Maringanti, B. K. Schaffer, and J. H. Popp ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)328 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Nonpoin source pollution of surfarce and ground waters from agricultural activities is one of the most challenging watershed management issues faced today. A total maximum daily load (TMDL) developed to control nonpoint source pollution requires decision about specific reduction in loads from various land use activities and effectiveness of best management practices in accomplishing those load reduction goals. The objective of this study was to evaluate the efficacy of targeting and optimization BMP implementation strategies in reducing sediment transport from an agricultural watershed located in Arkansas. The results indicated that both approached could be effectively used to reduce sediment transport from agricultural areas. The results can be used to evaluate economic and environmental benefits of various management options within the watershed and to develop management plans for optimizing water quality protection and agricultural production in the watershed.

back to top

STREAM RESTORATION DESIGN TOOLS

Select this Article		Adaptive Management as a Framework for Ecosystem Restoration Lisa M. Fotherby, Ph.D., P.E., Scott M. McBain, and Nicholas G. Aumen, Ph.D. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)329 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The heart of adaptive management is moving forward with a management action in the face of uncertainty, acknowledging that a successful solution can not be deduced at the start of the program, but recognizing that inaction could impose further ecological degradation. These programs or projects are often developed and guided by committees of stakeholders, scientists, engineers and managers and the success of the program can depend on all participants finding common ground. Designing a program by committee can be challenging due to varied backgrounds, values, and the slower pace of reaching accord. Examples from the Comprehensive Everglades Restoration Plan, the Trinity River Restoration Program, and the Platte River Recovery Implementation Program are presented as illustrations of adaptive management concepts.

Select this Article		Kondolf Diagram for River Backwater Restoration F. Douglas Shields, Jr., Scott S. Knight, and Richard E. Lizotte, Jr. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)330 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Rehabilitation, protection, and management of riverine backwaters (floodplain aquatic habitats that are seasonally or periodically connected to the main channel) are becoming increasingly common. General criteria for selecting restoration goals and evaluating alternative designs are lacking. An approach for assessing aquatic system status before and after restoration proposed by Kondolf and others (http://www.ecologyandsociety.org/vol11/iss2/art5/) is based on assigning a position to the system in a four‐dimensional space that represents temporal variability on one axis and connectivity in the three spatial dimensions on the remaining three axes. Use of the Kondolf approach for evaluating restoration design for an example site is described. A plan featuring two small water control weirs was proposed, and a simple numerical water budget model was constructed to allow simulation of temporal variability and connectivity with the main river channel for any imposed annual hydrograph. The impacts of varying the backwater control structure (weir) design and its operation on Kondolf position were assessed using the model.

Select this Article		Stability Analysis in Stream Restoration A. Jacob Odgaard ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)331 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A perturbation stability analysis is used for development of a stable‐channel alignment. By introducing a small perturbation into the equations governing flow and sediment transport and analyzing the growth rate of the perturbation, the analysis leads to the ‘dominant’ channel‐wavelength and the channel alignment that has the greatest stability. A channel with such alignment will be the least destructive in terms of bank erosion and migration, and it will be a channel with minimal maintenance requirements. Graphs are developed that describe the dominant meander wavelength and phase shift as a function of primary flow and sediment variables. A numerical example is provided showing how the graphs are used to determine the optimum channel alignment given flow and sediment characteristics. Two channel stabilization projects are also described that benefitted from the stability analysis.

Select this Article		The PBS&J Scour Spreadsheet: A Tool for Stream Restoration, Utility Crossings and Streambank Protection Projects Leo R. Kreymborg, P.E. and David T. Williams, Ph.D., P.E., F. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)332 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Scour analyses are required for stream projects such as stream restoration, utility crossings, bridges, streambank. protection, levees and floodwalls. In lieu of sophisticated numerical models, simplified approaches are often utilized, especially for reconnaissance and feasibility studies. Neglecting local scour such as scour at bridges, the total scour using these simplified techniques is comprised of long term, general, bend, dune formation, and thalweg formation. There are several methods within each of these scour components and calculations are often tedious and repetitive. This presentation provides information on a free spreadsheet developed by PBS&J that computes the most commonly use scour methods. The power of the spreadsheet is in the use of inputting the variables once and computing the results using numerous methods. These scour methods are: 1. General scour, based upon 7 methods, 2. Bend scour, based upon 4 methods, 3. Equilibrium Slope, based upon 4 methods, 4. Incipient motion, based upon Shield's diagram, 5. Bedform scour, based upon 2 methods. The spreadsheet also includes a suggested matrix that aids in assuring that there is no “double counting” of scour components when computing the total scour.

back to top

UPLAND EROSION MANAGEMENT AND MODELS

Select this Article		Evaluating the Performance of the Water Erosion Prediction Project (WEPP) Model for Larger Watersheds O. Abaci and A. N. Papanicolaou ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)333 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The major water quality impairment in the Midwest United States is sediment eroded from agricultural lands. Yet, few understand the spatial and temporal variability of erosion, or soil erosion dynamics, in relation to precipitation, topography, land management and severe events. Long‐term measurement of erosion is expensive and not practical. Utilizing process based, distributed models such as WEPP allows an inexpensive and quicker way of predicting spatial and temporal variation in erosion. One key limitation of the WEPP model is the maximum “field” size that the model is applicable to. This paper questions the performance of WEPP model for a 26 km² watershed which is 10 times larger than the maximum size (2.6 km²) documented in the literature. WEPP predicted sediment delivery ratio (SDR) values as a function of the drainage area is compared with the values reported in the literature. Although WEPP tends to overestimate the SDR values compared to the reported values, the predicted values follow the overall trend. To further examine the performance of WEPP, the SDR was plotted as a function of the runoff coefficient, defined as the runoff/rainfall ratio. In semi‐humid environments such as the focused study site (South Amana Catchment of Clear Creek Watershed, IA) runoff and raindrop impact to erosion may be significant. The WEPP predictions are compared against the statistical relation of SDR vs. runoff coefficient which was developed for watersheds in Iowa. It is shown that WEPP results compare well with the statistical relation which suggests that WEPP might be applicable to larger sized watersheds than documented in the literature.

Select this Article		Illinois River CREP: Sediment and Nutrient Delivery Assessment M. Demissie, Ph.D., P.E., Jim Slowikowski, Laura Keefer, and Kip Stevenson ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)334 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The Illinois River Conservation Reserve Enhancement Program (CREP) was initiated as a joint federal/state program with the goal of improving water quality and wildlife habitat in the Illinois River Basin. Based on long‐term data and research, the two main causes of water quality and habitat degradations in the Illinois River were sedimentation and nutrient loads. To address these issues, the two main objectives of the Illinois River CREP are: 1) reduce the amount of silt and sediment entering the main stem of the Illinois River by 20 percent, and 2) reduce the amount of phosphorous and nitrogen loadings to the Illinois River by 10 percent. To assess the progress of the program towards meeting the two goals, the Illinois Department of Natural Resources (IDNR) and the Illinois State Water Survey (ISWS) are developing a scientific process for evaluating the effectiveness of the program. The process includes data collection, modeling, and evaluation. The monitoring and data collection component consists of a watershed monitoring program to monitor sediment and nutrient for selected watersheds within the Illinois River Basin and the collection and analysis of land use data throughout the river basin. Data collected at the monitoring stations and long‐term data collected by other agencies are being used in evaluating the trends in sediment and nutrient delivery to the Illinois River. The paper presents results of the assessment based on available data.

Select this Article		Quantifying Runoff and Erosion Response to Conservation Practices at Fort Hood, Texas June E. Wolfe, III, Dennis W. Hoffman, and T. J. Gerik ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)335 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Military training lands suffer environmental impacts and erosion problems due to heavy vehicle operation; monitoring storm runoff is useful for quantifying water mediated erosion and evaluating Best Management Practice (BMP) effectiveness. We measured precipitation, runoff, sediment concentration, and the sediment mass lost during 60 storm events in the Shoal Creek watershed at Fort Hood, Texas. Precipitation, storm runoff, and sediment losses were compared between the pre and post BMP implementation periods. Mean storm runoff was reduced by 61 percent, mean sediment concentration was reduced 71 percent, and mean sediment load was reduced greater than 90 percent. We further evaluated BMP effectiveness with a “No Practice Scenario” using the Agricultural Policy Extender (APEX) model. Model predictions of runoff and sediment loads were within 9 percent of measured field values.

Select this Article		Real Time Optimal Monitoring Network Design in River Networks Ilker T. Telci, Kijin Nam, Jiabao Guan, and Mustafa M. Aral ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)336 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The components of a river monitoring network design study would include the selection of the water quality variables, identification of the location of sampling stations and determination of the sampling frequencies. These are primary design considerations which may require a variety of objectives, constraints and solution methods. In this study we focus on the optimal river water quality monitoring network design, which determines the optimal locations of data collection points, based on continuous measurements at these locations for a generic single or multiple contaminant sources. In the proposed model, the locations of sampling sites are determined such that “the contaminant detection time is minimized” for the overall river network while achieving “maximum reliability” for the system performance. In the proposed methodology, a water quality simulation model is used to generate the time series information for the concentrations of the water quality variables at the potential monitoring locations along the river network. Since contamination events may occur at any time within the simulation period in multiple occurrences, dynamic hydrodynamic and fate and contaminant transport analysis of the overall system would be necessary to arrive at the optimal design. For comparison purposes, the proposed model is tested on a simple network that has been studied in the literature. The comparative analysis of the design generated in this study and the outcome presented in the literature is discussed for various contamination scenarios. The results indicate that steady state solutions or solutions that are based on the geometry of the river network may not provide a reliable solution for the network design problem considered here and a dynamic analysis may be necessary to solve this important problem. The results show that the proposed model can be effectively used for optimal design of monitoring networks.

back to top

URBAN STREAMS

Select this Article		A Case Study of Channel Change during Urbanization: The San Antonio River from 1830–2004 Joanna C. Curran, A. M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)337 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The lower San Antonio River basin presents the opportunity to study channel planform change during urbanization in the study reach. Using a GIS framework, channel migration is measured over the period from 1838–2004. While the bulk of the watershed area remains rural, the effects of a large, urbanizing core extend throughout the reach. The physical processes governing river morphology in the watershed have a strong spatial component. The upper and lower portions of the study area respond differently to changes in the flow and sediment regimes related to increased impervious cover. By examining morphology change over a long time frame, the affect of urbanization on natural channel change can be determined. This research was motivated by the need to establish minimum in‐stream flows for the San Antonio River. Significant alterations to the River are best understood when examined over large spatial and temporal scales, illustrating the need to understand the physical processes governing channel change.

Select this Article		Central Arroyo Seco Stream Restoration near Downtown Los Angeles Wendy Katagi, Theodore Johnson, P.E., and Timothy Brick ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)338 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The purpose of the Central Arroyo Seco stream restoration in Pasadena, California is to create habitat conditions suitable to sustaining the arroyo chub, a native fish of the Arroyo Seco. Current instream conditions within the natural channel reaches are characterized by adequate over bank vegetative cover but an absence of pools needed for refuge and resting areas and juvenile rearing and relatively few trailing vegetation or other firm substrate like rocks or logs in slower flowing runs needed for spawning. The natural channel reaches are also subject to flash flood events due to the highly impervious upstream‐urbanized watershed, operational releases from the Devils Gate Dam and the hydraulic efficiency of the concrete‐lined channel reach. Proposed improvements consist of backwater pools, riffle/weirs located at the upstream and/or downstream ends of the backwater pools, and a series of wing deflectors and snags. Local materials including boulders, fallen trees and logs, and root wads will be utilized, to the extent feasible, in the construction of stream channel enhancements.

Select this Article		Evaluating the Effects of Urbanization on Stream Flow and Channel Stability — State of Practice D. W. Baker, P.E., M. ASCE, C. A. Pomeroy, Ph.D., P.E., M. ASCE, W. K. Annable, Ph.D., P.Eng., M. ASCE, J. G. MacBroom, P.E., M. ASCE, J. S. Schwartz, Ph.D., P.E., M. ASCE, and J. Gracie ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)339 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The hydrology from urban areas has a profound effect on the stability of our urban streams. The urban condition increases peak flows and the volumes of runoff from the watersheds. Detention storage common in urban areas can extend the time that these flows occur in the streams, and possibly change sediment discharge characteristics. The effects on bank stability, aquatic and riparian habitat, sediment transport, and water quality are subjects of current research. Continuous simulation modeling of runoff in urban streams is currently being studied to determine the effects of urbanization on urban streams. The continuous simulation modeling helps characterize the effect of prolonged flows on stream stability. Research has shown that simply limiting peak flows may not be enough to maintain pre‐development stability levels. The duration of the flows can affect the stability as much as the magnitude of the flow. The methodology used in developing the continuous simulation hydrology is also extremely important to understand. The determination of bankfull discharge in urban streams is a continuing mystery. Recent research out of Canada has shown that the correlation of bankfull discharge, or morphological forming discharges, to a specific runoff event return interval is not possible. This revelation is extremely important and may invalidate design criteria across the U.S. related to the use of the one‐year or two‐year return interval flow for stream stability analysis. In addition to bankfull discharge, it has been determined that another discharge should be considered for urban streams. Those discharges relate to the requirements of aquatic habitat at different life stages and are critical to the ecological integrity of the stream system. Design of channels based on morphological forming discharges, in conjunction with these ecological sustaining flows, result in stable channels that provide self‐sustaining habitats, diverse enough in structure that they provide essential ecological functions. Finally, effects of upstream detention on stream stability and ecological integrity have long been debated. Studies currently underway seek to answer the question whether, “to detain or not to detain, because detention facilities may be storing sediment leading to channel instabilities, coupled with longer duration storm hydrographs. This paper will summarize the findings of these and other important questions and studies related to stream stability and ecological integrity.

Select this Article		Stream Restoration Design Hydrology James G. MacBroom, P.E. and Elsa Loehmann ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)340 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Stream restoration projects often include the physical reconstruction of channel cross sections, profiles, or realignment in order to provide ecological succession. The channel's width, depth, and slope are adjusted to convey a design discharge using analog, empirical, or analytical techniques. It has become common practice for restoration projects to be designed for a single flow rate that represents a channel forming discharge that creates an idealistic equilibrium alluvial channel. The channel forming discharge is estimated based upon the channel's bankfull discharge, effective (sediment transport) discharge, or by a specific flow frequency. The channel forming discharge or its surrogate is thought to have a geomorphic influence equivalent to the full range of all flows at a specific location resulting in a stable self‐formed channel. However, creating a stable bankfull channel does not necessarily address other fluvial processes and functions. Aquatic species in natural channels have adapted to require a wide range of flow regimes, and created channels need to have suitable forms for low and high flow processes. Restored channels should have profile features and cross sections that create low flow habitats, enable fish passage during migratory seasons with suitable velocity and depth, and should have bed material suitable for benthic species and fish spawning. Stream restoration projects should also consider the role of large floods that exceed the bankfull discharge. Projects designed only for bankfull discharges neglect the assessment and potential adjustment of overbank riparian wetland and floodplain ecological processes, such as plant seeding and germination, nutrient exchange, woody debris relocation, sediment distribution, arid the stimulation of fish migration. Large flood flows may cause channel aggradation, degradation, channel migration, cut of meanders, and avulsions that damage or supercede restoration projects. Urban stream projects should consider flood water profiles, property impacts, utility interruptions, and stream crossings at culverts and bridges. Many watersheds do not have static hydrology due to land use changes, loss of storage, floodplain encroachments, and climate change. Designers should consider future stream flow rates and not depend solely on the past discharges that create historic channel regimes. This paper advocates use of multiple hydrology criteria to facilitate the understanding of both biological and geomorphic processes. Restoration projects should consider seasonal biological and habitat needs during low instream flows, plus the impact and accommodation of larger than bankfull flood flows.

back to top

WATERSHED HYDROLOGY

Select this Article		An Online Watershed Weekly Journal — Communicating South Florida's Hydrology in Weblog Robert V. Sobczak and Ananta Nath ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)341 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract How many investors grab a newspaper to view the trend lines of key financial indices? Or, how many sports fans in their younger days unwound the rubber band from their stack of baseball cards to study the career statistics of their favorite players? Whatever one's business, knowing the numbers and watching where new numbers place in the historical parade of numbers that came before them, is both fun and empowering. To keep abreast of the happenings on sensitive regional water resources, from hydrology numbers to water politics, the Big Cypress Watersheds Restoration Coordination Team has developed a weekly weblog named the South Florida Watershed Journal (SFWJ). SFWJ illuminates and celebrates the water cycle and complex inner workings within and among the wetlands and waterways of the Kissimmee‐Okeechobee‐Everglades (KOE) and adjacent Big Cypress watersheds (http://sfwj.blogspot.com). The weblog provides a place where stakeholders of water resources and the interested public can quickly glance at and digest the numbers and graphics — just like looking at a watch — in a way that keeps them in tune with the constant tick of the region's water cycle and watersheds. It includes a weekly narrative, an interactive database, news‐links, and other features of socio‐political water interest. The watersheditorials provide a forum to discuss regional water resources projects and policies to obtain feedback from aquatic resources professionals across Florida. SFWJ can certainly serve as a model on‐line journal for implementing forums for local/regional water and environmental resources information.

Select this Article		Verifying Curve Numbers in Arid Environments by Combining Detailed Geomorphic Mapping and Pedotransfer Functions Julianne J. Miller, Todd G. Caldwell, Michael H. Young, and Graham K. Dalldorf ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)342 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Rainfall‐runoff models, such as HEC‐1 and HEC‐HMS developed by US Army Corps of Engineers' Hydrologic Engineering Center (HEC), are commonly used in the southwest US to estimate flood discharges because most watersheds in this region are ungaged and do not have stream discharge data. Most rainfall‐runoff models do not directly account for the initial abstraction (Ia), which is defined as the amount of precipitation that initially infiltrates into the soil prior to the occurrence of runoff. Rather these models rely on precipitation loss components that are considered to be subbasin area averages, such as the Soil Conservation Service (SCS‐ now Natural Resource Conservation Service) curve number (CN) approach. The purposes of this study were to characterize soils of a remote basin in southern Nevada, specifically runoff potential and soil hydraulic conductivity (Ks), and to examine the use of a site‐specific pedotransfer function (PTF) to relate soil texture and bulk density to CNs. Geomorphic mapping, soil sampling and analysis, rainfall simulation, and tension infiltrometer (TI) tests were ail used as field characterization techniques on six distinct geomorphic surfaces determined within the 22 km² study watershed. Rainfall simulation tests allowed for field‐measured CNs to be determined for these surfaces. High CN values occurred on the well‐developed desert pavement surfaces of the alluvial fan and lower CN values occurred on the younger and dissected alluvial fan deposits. Field measurements from the TI tests showed higher Ks values on the younger and dissected surfaces‐, and lower values on the older and well‐paved surfaces. Thus, CN inversely corresponded to Ks. The use of detailed geomorphic mapping significantly reduced the variance in Ks (and hence CN, as well) across the watershed, resulting in statistically distinct hydrologic groups that could be scaled to the watershed. When the average Ks was regressed onto field‐measured CNs, a linear relationship was found at R² = 0.928, demonstrating that Ks measurements may be used to estimate CNs in this watershed. In addition, a site‐specific PTF method showed that soil particle size distributions and bulk density were good predictors of Ks (R² = 0.890). Therefore, at this field site, less arborous soil characterization data and the site‐specific relationships obtained by more rigorous field work, CNs and other parameters for this watershed could be easily estimated. Using field‐measured site‐specific data to accurately assign CNs is important for verifying hydrologic models used for design of flood hazard mitigation structures. These studies suggest that field verification, which in the past was deemed cost‐prohibitive in large remote watersheds, could be cost‐effective and efficient using a similar approach.

Select this Article		Water Yield from Harvesting and Thinning Southwestern Mountain Forests: Historical Experience from US Forest Service Research Daniel G. Neary, Karen A. Koestner, and Boris Poff ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)343 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Subsequent to the extreme fire seasons of 2000 and 2002, extensive thinning of Southwestern mountain forests has been designated as the preferred practice to minimize the likelihood of widespread stand‐replacing fires. Concurrently, historical hydrologic research been incorrectly popularized to indicate that forest canopy removal can measurably augment water yields from forested watersheds. A popular misconception has therefore arisen that these two usually incompatible goals can be achieved simultaneously on the same land. Responsible and appropriate silvicultural activities for other purposes, such as fire risk reduction, may increase water yield from upper elevation forests or improve water balance within lower elevation forests, depending on the intensity of canopy removal, tree species, latitude, elevation, and aspect. These same activities may also restore other desirable landscape characteristics and should not be directed solely at water yield. Increases in water yield will be difficult to quantify, especially at the scale of large basins, like the Salt River, that provide for large municipalities. Therefore, short term increases in water yield from forest canopy removal should be considered a serendipitous benefit if and when it occurs in conjunction with other advantageous results.

back to top

BRIDGE SCOUR A

Select this Article		An Experimental Study on the Local Protection Measures of a Bridge Caisson Zheng‐Yi Feng and Yu‐Hsuan Chang ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)344 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract This study performed hydraulic model experiments on the local protection measures of a bridge caisson. The purpose of this study is to understand the scouring phenomenon, protection efficiency and feasibility between the various protection measures as a reference for protection design of bridge local scouring. According to the bridge caisson on site, the in‐situ check dam and planned three protection measures, eleven sets of experiments were designed and carried out. In addition, sediment supplement from upstream was also simulated. The sandy bed forms around the model bridge caisson were measured before and after each test. Also, the bed form variations were measured from the side of the flume to understand the influence of the check dam and the protection measures. From the experimental results, it is discovered that the existence of the check dam in the downstream has the strongest influence on bed forms and local scouring depth. Among the simulated protection measures, the effectiveness of the protection using circular piles is shown unsatisfied. All the other protection measures are shown having some certain degree of effectiveness.

Select this Article		Experimental/Feasibility Study of Radio Frequency Tracers for Monitoring Sediment Transport and Scour around Bridges T. J. Lauth and A. N. Papanicolaou ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)345 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The scour occurring around bridge piers in sandbed rivers can greatly affect the life of the pier, and overall structural integrity. Few methods exist for tracing sand particles due to the difficulty in reproducing particles that mimic the geometric properties and specific gravity of sand particles. The focus of this research is to develop a tracing technique for sand particles focusing on using artificial coarse sand particles and a Radio Frequency Identification (RFID) system. An RFID system consists of programmed transponders and a corresponding reader that communicate using radio waves. This communication provides the ability to track individual particles with embedded transponders (from here on referred to as seeded particles) allowing for an estimate of scour. RFID has many potential benefits over other tracing technologies. However, there are still challenges facing RFID technology before it can be implemented as a replacement to other tracing technologies, such as unknown performance in aquatic environments and the relationship between transponder particle movement and actual scour. To address these issues, an RFID system was built in a laboratory setting to measure the parameters (e.g. maximum burial depth, signal interference due to turbulence, etc.) that must be known for field implementation and to develop a relationship between particle movement and scour. A matrix of desirable individual parameters, including scour, were tested in a sandbed flume. Initial testing has revealed mixed results about the viability of the system, as the maximum unburied detection range has been small, the casing material has shown a potential for significant interference, and transponder orientation as had a large effect on read range. Some of this issues can be addressed with alterations to the system (more power, different antenna), which will require further testing.

Select this Article		Water Quality Aspects of Partially Grouted Riprap P. E. Clopper and C. I. Thornton ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)346 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract In Europe, partially grouted riprap (as contrasted with fully grouted riprap as historically used in the United States) has been successfully used for several decades to prevent erosion of the beds, banks, and shorelines in riverine and coastal environments such as rivers, canals, lakes, and harbors. This type of armoring treatment is also used to protect against local scour at structures such as bridge piers and abutments. Partial grouting in Europe is often performed under water, or in flowing water. Due to the concern for temporary water quality impacts during placement, this aspect may be a potential impediment to the acceptance and implementation of this technology in the US. Many sites cannot be dewatered during construction or rehabilitation activities; therefore, the ability to place grout under water or in “live stream” conditions while maintaining water quality parameters within acceptable limits is of paramount importance. Various degrees of grouting are possible, but optimal performance of the partial grouting technique is achieved when the grout is effective at “gluing” individual stones to neighboring stones at their contact points, leaving relatively large voids between the stones. This makes the partial grouting technique appealing for a number of reasons: 1) Because it is permeable, partially grouted riprap provides a more suitable alternative to total grouting because it alleviates the buildup of pore pressure beneath the system; 2) It remains flexible by allowing groups of stones to remain connected as an equivalent “conglomerate” particle; 3) Partial grouting allows the use of smaller rock compared to loose riprap; and 4) A thinner overall riprap blanket is achieved using the partial grouting technique. This paper presents selected aspects of NCHRP Research Project 24‐07(2), “Countermeasures to Protect Bridge Piers from Scour” as related to partially grouted riprap. That project resulted in the publication of NCHRP Report 593 of the same name. Methods for placing partially grouted riprap in flowing water at prototype scale are presented, and include detailed results of water quality monitoring conducted under these conditions. The installation was representative of protection against local scour at a bridge pier in a riverine environment. Further testing of the installation demonstrated its inherent stability in the high velocity, highly turbulent flow field at the pier.

back to top

BRIDGE SCOUR B

Select this Article		Copper River Channel Migration and Its Effects on the Copper River Highway J. S. Conaway and T. P. Brabets ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)347 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The Copper River in southcentral Alaska drains an area of more than 62,700 square kilometers. Near its mouth, it flows into a large alluvial plain known as the Copper River Delta. The banks and streambeds of the Copper River Delta are readily erodible and thus channels constantly scour and migrate. The Copper River Highway traverses this dynamic and complex network of braided channels via 11 bridges. Over the last decade, several of these bridges and the highway have sustained serious damage from high flows in excess of 12,000 cubic meters per second and channel instability. Scour monitoring, LIDAR data, bathymetry, hydrologic data, and hydrodynamic modeling are being used to investigate the cause and timing of the channel migration and future impacts to the highway and its bridges. The distribution of flow through these bridges was relatively stable until the mid 1990s. In 1991, up to 68 percent of the Copper River flowed through 3 bridges on the western side of the Delta. In 2004, these same bridges conveyed only 8 percent of the flow while 90 percent of the overall discharge flowed through 3 bridges on the eastern side of the delta. Migration of the river across the delta and redistribution of discharge has resulted in streambed scour at the bridges, overtopping of the road during high flows, prolonged highway closures, and formation of new channels through forests. Scour monitoring equipment and channel soundings at the eastern bridges have recorded up to 13.4 meters of fill at one bridge and 7.3 meters of scour at another bridge. The scour and fill are the product of the overall redistribution of flow and local channel migration at the bridges. A combination of LIDAR and aerial photography taken at various times from 1950 to the present indicate that the channel migration from west to east begins immediately downstream of where the river splits from a single channel to numerous braids. Long‐term delta evolution would result in periodic channel migration back and forth across the delta, and in south‐central Alaska, tectonics and isostatic adjustments may affect geomorphic processes. The immediate cause of the channel migration could be the result of natural adjustments following large floods in 1981, 1995, and 2006, or the result of channel formation during ice jams. Current observations indicate the eastern channels are becoming more established and will continue to threaten sections of the highway and several bridge crossings.

Select this Article		Partially Grouted Riprap as a Pier Scour Countermeasure P. F. Lagasse, P. E. Clopper, and L. A. Arneson ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)348 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Partially grouted riprap consists of specifically sized rocks that are placed around a pier and “glued” together with grout. In contrast to fully grouted riprap, partial grouting increases the overall stability of the riprap installation unit without sacrificing flexibility or permeability. It also allows for the use of smaller rock compared to standard riprap, resulting in decreased layer thickness. The system typically includes a filter layer, either a geotextile fabric or a filter of sand and/or gravel, specifically selected for compatibility with the subsoil. Tests conducted under National Cooperative Highway Research Program (NCHRP) Project 24‐07(2) confirmed the applicability of partially grouted riprap as a scour countermeasure for bridge piers. After placing the rock, the voids of the riprap matrix are then partially filled with a Portland cement based grout by hose or tremie, often under water. The final configuration results in an armor layer that retains approximately 1/2 to 2/3 of the void space of the original riprap. Hydraulic stability of the armor is increased significantly over that of loose riprap by virtue of the much larger mass and high degree of interlocking of the “conglomerate” particles created by the grouting process. NCHRP Project 24‐07(2) “Countermeasures to Protect Bridge Piers from Scour” included investigation of partially grouted riprap installations in Germany and laboratory investigations at Colorado State University at prototype scale as a basis for developing guidelines applicable to U.S. practice for this technology. This paper summarizes Design Guidelines for partially grouted riprap as a bridge pier scour countermeasure.

back to top

SEDIMENT DYNAMICS POST DAM REMOVAL A

Select this Article		Developing Mitigation Plans for Matilija Dam Removal Blair Greimann, Peter Sheydayi, Sergio Vargas, Yong Lai, and Brent Mefford ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)349 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Matilija Dam in Ventura County, California is being considered for removal. Approximately 6 million cubic yards of sediment has accumulated behind Matilija Dam near Ventura, California since its construction in 1947, and only 7% of the original reservoir capacity remains. It is also a barrier to the migration of Steelhead Trout in the Ventura River Basin. The relatively flat, low‐lying areas adjacent to the lower 14 miles of the Ventura River are, for the most part, extensively developed, and prone to inundation despite appreciable flood control measures. In addition, an important water supply diversion is located approximately 2 miles downstream of the dam. Two requirements of the project are to maintain the current water diversions and to maintain or reduce the current flood risk. This paper describes the analysis performed and procedures followed to develop plans to meet these requirements.

Select this Article		Experimental and Field Observations of Breach Dynamics Accompanying Erosion of Marmot Cofferdam, Sandy River, Oregon G. E. Grant, J. D. G. Marr, C. Hill, S. Johnson, K. Campbell, O. Mohseni, J. R. Wallick, S. L. Lewis, J. E. O'Connor, J. J. Major, and B. K. Burkholder ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)350 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A key issue faced in dam removal is the rate and timing of remobilization and discharge of stored reservoir sediments following the removal. Different removal strategies can result in different trajectories of upstream sediment transport and knickpoint migration. We examine this issue of for the Marmot Dam removal in Sandy River, Oregon, USA using both physical experiments and field studies accompanying removal of the dam in October 2007. The physical experiment was designed to provide insights on how and if the position of a cofferdam notch will affect how reservoir sediments are remobilized, with the goal of minimizing the volume of sediment stranded in terraces. Data and observations indicate that at lower failure discharges, notch position impacts the location of cofferdam failure as well as the location of the first major knickpoint and its trajectory. In particular, notch positions that force the river to migrate laterally in order to adjust to natural valley orientation and morphology were most effective in removing larger volumes of sediment and reducing terrace heights. Actual cofferdam notching to maximize erosion produced extremely rapid and significant erosion of reservoir sediments. Comparison of model results with field observations suggests that the physical experiments provided solid predictions of rates of erosion and overall knickpoint trajectory.

Select this Article		Sediment Dynamics Post Dam Removal: State of the Science and Practice Laura Wildman, Cassie Klumpp, Blair Greimann, and James MacBroom ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)351 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract In July 2005 the EWRI/ASCE Task Committee on Sediment Dynamics Post Dam Removal brought together many national experts, both in research and practice, on the specific topic of sediment dynamics post dam removal. Twenty‐five papers were presented regarding the state‐of‐the‐science and state‐of‐the‐practice in considering sediment remobilization and channel dynamics post dam removal. Additional papers reflecting current approaches on this topic were then added to the initial 25 and compiled into a monograph. Authors included representation from federal agencies, universities, consulting firms, environmental non‐profit organizations, and academic research laboratories, as well as state agencies; including engineers, geomorphologists, academic researchers, hydraulic/hydrologic modelers, model developers, ecologists, and fisheries biologists. The papers reflect the large regional and project‐specific variety relating to this topic. Subjects covered include physical models, numerical simulations, specific case studies, decision‐making processes, individual dam issues, geomorphic changes, channel bed evolution, downstream sediment transport, ecological implications, lessons learned from case studies, and sediment quality. Further, these papers encompass the wide variety in sediment composition, hydrologic region, and project scale. This paper will summarize the findings in the monograph papers, and therefore the many national ongoing efforts and the state‐of‐the‐science/practice in the field of sedimentation as it relates to river dynamics post dam removal.

Select this Article		Sediment Management during Low Dam Removal James G. MacBroom and Elsa Loehmann ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)352 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Sediment management has become one of the key issues during the removal of dams, irregardless of whether the dam is removed because it is obsolete, unsafe, ecologically harmful, or simply unwanted. Many sediment management techniques have been used at low dams. The first step in removal is to assess potential downstream impacts and sediment transport to determine whether natural erosion of the sediment is tolerable and permitted by regulatory agencies. Active sediment management is appropriate along streams that are sensitive due to water supply sources, aquatic habitats, presence of rare and endangered species, recreation, contaminated sediment, or rivers with flood hazards. Sediment management options include use of excavated channels, headcut controls, partial sediment relocation, sediment removal, bypass channels, and partial breaches. Active sediment management helps to minimize the downstream impact of excessive sediment releases. In addition, it can aid the formation of a new upstream channel across the former pool area, provide fish passage, and accelerate aquatic and floodplain habitat restoration. In contrast, passive sediment management allows natural processes to readjust the sediment deposit and form a new channel that is proportional to water discharges and sediment loads.

back to top

SEDIMENT TRANSPORT MODELING A: EXPERIMENTAL CASE STUDIES

Select this Article		Analysis for the Dispersion Zone of Sediment Concentration Flowed into the Small Estuary Sang‐Kil Park, M. ASCE, Jong‐Su Yoon, Byung‐Dal Kim, Un Ji, and Do‐Hoon Kim ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)353 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The diffusion zone of sediment concentration in a small estuary and a coastal area with and without jetties was analyzed using numerical and physical models. It was assumed that sediment concentration was constant during intermediate flows, and was high in the beginning of high floods and decreased over time. The sediment diffusion zone and concentration for three cases, without the jetty, with only south jetty, and with the jetty, were examined in this study. In addition, the jetty was constructed in the field with the same design used in numerical and physical modeling and the diffusion zone of sediment concentration was monitored. The field data was similar to the results of numerical and physical modeling. Therefore, the reduction rate of sediment concentration by waves and the diffusion zone affected by increased sediment concentration were obviously decreased due to the construction of the jetty.

Select this Article		Bank Erosion of the Illinois River Nani G. Bhowmik, Ph.D., P.E., F. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)354 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The Illinois River is a major tributary of the Mississippi River draining about 75,000 sq km of land in the States of Illinois, Indiana and Wisconsin. Most of the drainage area is contained within the State of Illinois. The river originates near Chicago, Illinois and after traveling about 500 km within the State of Illinois, it joins the Mississippi River near Alton, Illinois upstream of the City of St. Louis. The river has been altered over the years especially in 1939 after a series of Locks and Dams were constructed to facilitate the movement of river traffic. Two detailed attempts were made in the history of the river to document the bank erosion of this river. Both the research was conducted by the author with assistance from a number of colleagues and associates. The present research was completed to identify the erosion sites including their severity, probable causative factors and the development of a classification system. During this research, a team of engineers, geomorphologic experts and field professionals traveled the entire length of the river by boats extending several weeks. During this trip, a number of typical bank erosion sites were identified, bank material samples were collected, data on river cross‐sectional profiles were collected, photographs were taken, and a field evaluation of the causative factor or factors were noted. Subsequently, all the field data were evaluated and bank erosion sites were classified. Based on this analysis, all the sites were classified into six separate classifications based on the probable causative factors of bank erosion, bank material composition, and the geometrical features of the banks. Bank erosion of any river occurs as a result of a variety of natural forces and human induced activities. The analysis for the Illinois River has shown that about 74% of the bank erosion sites were subjected to seepage flows. About 28% of the bank sections have shown the evidence of river traffic induced impacts. Other causative factors included eddy currents, disturbed flows due to exposed tree roots, surface drainage, and weathering due to rapid freezing and thawing cycle. This research will guide the future management activities of the Illinois River as far the river bank erosion process is concerned.

Select this Article		Pattern Observation during Bed‐Form Development Heide Friedrich and Bruce W. Melville ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)355 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Most natural patterns exhibit some form of complex behaviour. Underwater bed forms generally start small and appear initially to be disorganized. They grow in height and spacing and become better organized through interactions and mergers between bed forms. For this study, spatial plan‐view bed‐form development patterns are studied visually. Photographic images of bed‐form growth starting from a flat bed in fine uniform sand are obtained in a laboratory flume environment. Various merging and termination processes are identified. Literature review shows that the observed pattern changes during early bed‐form development are similar to processes observed for aeolian dune fields.

Select this Article		Study of Sediment Source and Fate Processes Using Isotopic Tracers in the Bluegrass C. M. Davis, S. M. ASCE and J. F. Fox, M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)356 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract This study examines temporal and spatial variations in sediment organic matter at the watershed scale to better understand organic carbon and nitrogen cycling in‐stream in a watershed exhibiting high in‐stream storage. Temporally integrated weekly sediment samples were collected at multiple sites within a central Kentucky watershed over a nine‐month sampling routine and analyzed for organic tracer distributions including stable carbon and nitrogen isotopes, total organic elemental carbon, total element nitrogen, and the carbon to nitrogen ratio. Results of this study showed distinct seasonal variations in the sediment organic tracers; spatial and hydrologic parameters were not as significant. All of the variations are attributed to microbial cycling of organic matter within temporary in‐stream storage zones due to the single primary ex situ erosion source remaining consistent throughout the sampling routine.

back to top

SEDIMENT TRANSPORT MODELING B: 2‐D MODELS

Select this Article		Incorporating Sediment Mass Balance into a Meandering River Model Jianchun Huang, Blair P. Greimann, and Timothy J. Randle ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)357 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract An updated computer model for meandering rivers has been developed using the Linearization Analyses of Johannesson and Parker (1989) and Sun et al. (2001a, b). The model simulates the bed topography, flow field, and bank erosion rate in a curved channel with an erodible bed. Sediment mass balance is preserved and to update the channel bed elevation, which is represented by a 2D cell with high elevation area, water surface elevation area, and low elevation area. The model is used to simulate a laboratory channel migration where the upstream channel migration is slowed down due to channel erosion and high bank height.

Select this Article		Predicting Contraction Scour with a 2D Model Yong G. Lai and Blair P. Greimann ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)358 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Contraction scour is often encountered in natural rivers due to channel contraction or river restoration structures. Such scour may be predicted better with multi‐dimensional models than 1D models. It has been reported that the 2D depth‐averaged model is inadequate for modeling the contraction scour. This study aims to investigate whether other factors may play important roles in the poor performance of 2D models. In the process, an improved prediction using the 2D model is obtained and factors influencing the model prediction are identified. The motivation of the study stems from the fact that a 3D model is too complex and many engineering applications have to rely on 2D models. This study shows that the 2D model is still adequate for predicting the contraction scour.

back to top

SEDIMENT TRANSPORT MODELING C: COMPUTATIONAL

Select this Article		A Stochastic Diffusion Jump Model of Suspended Sediment Transport in Hydrologic Extreme Events Christina W. Tsai, M. ASCE and Jung Sun Oh, S. M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)359 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Movement of sediment particles in surface water can be described by a stochastic diffusion jump process. The proposed approach simulates sediment transport in hydrologic extreme flows by introducing the Poisson jump process. The stochastic differential equation (SDE) in the proposed stochastic model classifies the movement of particles using three major terms including a mean drift motion, a random Brownian type turbulent motion and jumps due to the hydrologic extreme events. The random term is represented by the Wiener process. The jump term is modeled as the Poisson process. The magnitude of particle movement in response to extreme flow events, characterized as the Poisson jump, depends on the characteristics of the extreme events and the properties of the sediment particles. The frequency of occurrence of the extreme events in the proposed model can be explicitly accounted for in the evaluation of movement of sediment particles. In the proposed SDE model for particle movement, the relaxation time, defined as the time needed for a particle to move from the regular flow state to the extreme flow state, is introduced. One example is presented to illustrate the realizations of sediment transport. The ensemble mean and variance of particle trajectory can be obtained from the proposed model via simulations.

Select this Article		Fréchet Distribution and Transport of Suspended Sediments Nazeer Ahmed, M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)360 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract For the design projects concerning the sediment control structures, a sedimentgraph is commonly used for the determination of sediment load generated by a drainage basin in response to the occurrence of a rainstorm on its surface. The division of total sediment load as attributed and carried by direct runoff and baseflow, respectively, is of paramount importance in these types of studies. A large sample of sedimentgraphs from different geographical areas of the 48 contiguous States is considered in this investigation. A two‐parameter Fréchet Distribution is fitted to each one of the sample sedimentgraphs. The two parameters of the Distribution are related to the dimensionless shape parameter and storage time constant for the same given drainage basin. Both parameters are determined through the analysis of the measured suspended sediment data. The calibrated form of the two‐parameter Fréchet Distribution describes the natural sedimentgraph curve well and furnishes accurate estimates of the sediments carried by the direct runoff and the baseflow, respectively.

Select this Article		Recent Advances in Sediment Transport Modeling Scott C. James, Matthew D. Grace, Michael Ahlmann, Craig A. Jones, and Jesse D. Roberts ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)361 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract SEDflume measures erosion rates as a function of sediment depth (down to a meter or more) and at high shear stresses (up to 25 Pa for data collection) to improve our understanding and ability to predict sediment transport and the capabilities of numerical models. In this work, a sediment transport model is developed specifically to incorporate these data. This model is a significant improvement over previous models because it directly incorporates site‐specific SEDflume data, while maintaining a physically consistent, unified treatment of suspended load and bedload. Experimental data from noncohesive sediment erosion experiments in a straight channel and around a 180° bend will be used to verify this model.

Select this Article		Soil Erosion and Sediment Yield Modeling with the Hydrologic Modeling System (HEC‐HMS) Jang Pak, Matt Fleming, William Scharffenberg, and Paul Ely ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)362 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The effects of surface erosion and stream sediment loading in watersheds have become increasingly important in water quality best management practices (BMPs), watershed management, and natural resources conservation planning. Many water resources studies must now consider the erosion related effects of watershed activities. Surface erosion models describe the detachment, deposition and transport of soil particles by the erosive forces of raindrops and surface flow of water from their point of origin to the watershed outlet. The current version of the Hydrologic Modeling System (HEC‐HMS) contains no capacity to simulate surface erosion processes; however, the need of erosion and sediment yield modeling exists throughout the Corps of Engineers, especially as the Corps moves towards watershed level investigations, including Total Maximum Daily Load (TMDL) studies. Therefore, the Hydrologic Engineering Center (HEC) has added existing, developed new and tested soil erosion and sediment yield methods to include in HEC‐HMS. The goal is to develop tools within HEC‐HMS that provide output necessary for making informed decision about managing soil erosion within the watershed. This paper discusses the addition of soil detachment, deposition and transport methodologies to the HEC‐HMS program These new sediment modeling tools will increase the application of HEC‐HMS for sediment modeling studies by directly computing sediment yield. An effort was made to ensure that sediment output from HEC‐HMS could be easily used as boundary conditions in HEC‐RAS for more detailed river mechanics modeling. Two surface erosion methods were included in the HEC‐HMS subbasin element to model sediment erosion/wash‐off for both pervious and impervious areas. In addition, an in‐channel sediment routing method was included in the HEC‐HMS reach element. These methods model the translation and attenuation of the sediment load along with deposition and erosion processes occurring in the channel.

back to top

UNDERGRADUATE AND GRADUATE STUDENT TECHNICAL PAPER COMPETITION WINNERS

Select this Article		Numerical Solutions to Dam Break Wave Propagation Burak Turan, S. M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)363 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract One‐dimensional flows in watercourses are modeled by solving Saint‐Venant Equations. Understanding these equations and numerical solution of them helps to overcome the problems resulted from propagation of flood and shock waves. In this study, a detailed analysis is implemented to solve one‐dimensional dam break problem. Different numerical techniques used for shock capturing are given and their performances are evaluated for two different dam break test cases. Numerical solution is achieved using two different finite‐difference schemes; explicit Gabutti and implicit Beam‐Warming algorithms, and finite‐volume scheme with limiters. Both, finite‐difference and finite‐volume schemes are second order in time and space. The numerical solutions are compared with analytical results. The errors from the analytical solutions are estimated and presented. The results show that convergence of finite volume schemes is better. The time and spatial variations of water depth and velocity are obtained and will be presented with the animations.

Select this Article		Solubility as a Mechanism for CSMR Effects on Lead Leaching Brandi N. Clark, S. M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)364 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The solution chemistry of Pb(II) at relatively low pH (≈ 3–5) was examined in the presence of chloride, sulfate, and phosphate. Lead sulfate solids are relatively insoluble even at pH 3. Pb(II) forms soluble complexes with Cl⁻ that can significantly increase the solubility of lead. Since lead solubility can be correlated to lead contamination problems in drinking water, the data suggest that chloride will worsen lead problems at low pH, whereas sulfate will decrease lead problems. The contradictory trends for the two anions may provide a mechanistic explanation for the success of the empirical chloride: sulfate mass ratio in explaining lead contamination of potable water. Specifically, the trends explain why lead contamination sometimes worsens when changing from alum (higher sulfate) to ferric chloride (higher chloride) coagulants.

Select this Article		Study of Pre‐Ozonation on Sand Filter Efficiency Earlan B. Dujon, S. M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)365 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The objective of the experiment was to determine the effects of pre‐ozonation on sand filtration efficiency and the reduction in turbidity. Although ozonation is primarily used for disinfection, it is stated in Libra's test that it also acts a powerful oxidizer and breaks down suspended solids. This will be analyzed based on the reduction in turbidity levels of the samples used. In this study three water samples were used; a simulated surface water sample, a stagnant lake water sample and a sample obtained from a pond with abundant wildlife. The traditional surface water treatment of settling followed by sand filtration reduced the turbidity by approximately 6% on average, however with pre‐ozonation the reduction was increased to over 30%. The simulated surface water showed a maximum reduction in turbidity of 80% with 188 mg/L dose. The maximum reduction in turbidity for the pond and lake water samples was 50% and 70%, respectively. The baseline suspended solids removal data of settling and filtration without ozonation resulted in an average reduction of 11%, likewise the reduction levels were increased dramatically with ozonation. Of the three samples the lake water showed a maximum reduction of approximately 90% with applied ozone dose greater than 500 mg/L. The Pond water showed only 70%, while the tap water showed a maximum reduction of 91% at doses greater than 500 mg/L. Thus pre‐ozonation may be an effective method to increase effectiveness is sand filtration systems.

Select this Article		The Application of CaSO₄ Soil Amendment to the Retardance of Rainwater‐Leached Metals from CCA‐Treated Wood Ash in Soil John D. Harden, S. M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)366 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The burning of wood treated with chromated copper arsenate (CCA) produces a toxic ash that is highly concentrated with As, Cr and Cu metals. The subsequent leaching of these metals from burn sites can produce soil and water contamination. Soils have varying natural abilities to reduce leaching and impact metals speciation and toxicity, by sorption, conversion and sedimentation related mechanisms. The goal of this research has been to determine the effectiveness of various soil amendments in the immobilization/retardance of As, Cr, and Cu species in ash produced from the burning of CCA‐treated lumber, and enhance our understanding of the role of amendments in the leaching of As, Cr, and Cu metals in a soil contaminated with CCA‐ash. Soil softener (CaSO₄ ⋅ 2H₂O) was evaluated for potential application as a low‐cost method of reducing the mobility of these toxic metals. Results of the investigation shows that although the control host soil retards the mobility of As & Cr, the CaSO₄ soil amendment further retards metals mobility by (72.4% and 77.3%), respectively compared to the control soil‐ash mixture. Cu mobility is increased by the presence of soil and by CaSO₄ amendment but at a much smaller mass rate.

back to top

CLIMATE CHANGE IMPACTS ON HYDRAULICS, HYDROLOGY I

Select this Article		Assessment of the ENSO Impact on Rainfall Characteristics and Frequency Analysis in South Korea Byung Sik Kim, Soo Jun Kim, Bo Kyung Kim, Hung Soo Kim, and Byung Ha Seoh ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)367 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Intensity‐Duration‐Frequency (IDF) curves are a form of frequency analysis used by engineers and scientists to create flood frequency estimations (Pilgrim, 2001). These frequency analyses are very important in the design of hydraulic structures to ensure that they are built economically and safely, that is, they are not over‐designed or under‐designed. IDF curves have traditionally been created by using historical data collected at a site and by assuming that this rainfall series is stationary and representative of the future. But as it has been proved in recent observations, climatic variability and trends do exist and their effects on rainfall have not been negligible. Increasing occurrences of the El Nino and La Nina phenomenon have lead to droughts and floods around the world, and long‐term trends in rainfall have been seen in all regions across Korea. The purpose of this paper is to evaluate impacts of ENSO on rainfall characteristics and IDF curves in South Korea. In this paper, first, rainfall data in 60 climate stations were categorized into Warm (EL Nino), Cold (La Nina), Normal episodes based on the Cold & Warm Episodes by Season, then 100 years of daily rainfall data were generated for each episodic event (EL Nino, La Nina) using Markov chain Monte Carlo (MCMC) model. Finally, IDF curve analysis and comparison for each episode were conducted. From the results, it shows that there are significant changes in the rainfall characteristics and IDF curves among Warm (EL Nino), Cold (La Nina) and Normal episodes.

Select this Article		National Costs to Meet Future Water Supply Production Needs in Africa under Climate and Demographic Changes Paul Kirshen ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)368 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Demographic and climate changes, urbanization, and globalization are creating stresses on many nations' water resources, including in Africa. Using climate change and demographic scenarios for 2050, it is found that large additional investments will be needed in water supply production facilities in the region over the next 25 years.

Select this Article		Statistical Behaviour of Adelaide's Rainfall — Is Climate Change Detectable? S. Beecham and R. K. Chowdhury ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)369 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The South Australian climate is changing towards less rainfall and consequently water security problems will be intensified (IPCC and CSIRO, 2007). In this study we attempted to identify the statistical behaviour of point rainfall measured at the Adelaide airport. Statistical moments, lag1 autocorrelation, the Buishand's Q test for homogeneity, the Mann‐Kendall test for trend and wavelet analyses for shift and temporal variability were carried out at fine (< 12 hour) and at coarse (monthly) temporal resolutions. Series of rainfall intensities at finer temporal scales and rainfall depths and proportion dry ratios at monthly scales were accumulated from the high resolution rainfall dataset. Homogeneity of rainfall intensity was found to increase as the temporal scale increases. Both rainfall intensities and monthly rainfall depths were found to be serially correlated. Except for July, the 2^nd, 3^rd and 4^th statistical moments of rainfall intensities decrease as the scale increases. While no statistically significant trends were found at finer and monthly scales using the Mann‐Kendall test, there were indications that trends are more likely as the temporal scale increases. Wavelet power spectra also showed this scenario noticeably. At very fine temporal scales (< 1 hour) rainfall intensities have large temporal variability and no trends or shifts in frequency level were detected. At the 12 hour and monthly temporal resolutions, statistically significant changes of dominant frequency level were observed in some months. Interestingly these changes were observed to happen after 1990.

back to top

CLIMATE CHANGE IMPACTS ON HYDRAULICS, HYDROLOGY II

Select this Article		Climate Change Impact on the Southwest Monsoon Modulated Freshwater Pulsation and Consequent Nutrient Flux Variability in the Continental Shelf of the Northern Indian Ocean Chandan Mahanta and Nayanjyoti Pathak ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)370 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Bay of Bengal compartment of northern Indian Ocean is one of the high productive areas of the world oceans where high organic carbon fluxes of more than 3 g m⁻²y⁻¹ have been recorded. Thermal and dynamic influence of Tibetan Plateau to north of BOB affects climatic modulation of organic matter fluxes through Ganges‐Brahmaputra to BOB continental shelf. In the light of Brahmaputra‐Ganges system carrying a high CNP load (computed as 6.24 × 10⁶ tons C/year, 8.5 × 10⁵ tons N/year, 8.4×10⁴ tons P/year) to the shelf, uncertainty about future effect on ecological and biogeochemical processes of Indian Ocean is increasing. The magnitude and direction of climate change impact could be significant both in relative and absolute terms. The future of biogeochemistry of Indian Ocean may be impacted significantly by the modified coupled C‐N‐P cycles since its role in evolution of marine ecosystem of Indian Ocean could be critical.

Select this Article		Climate Impacts on Hydrology in the Central United States: Application to Forecast Capability in the Republican River Basin Jae Ryu, Mark Svoboda, Tsegaye Tadesse, and Cody Knutson ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)371 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract For many water users and policy makers, the potential impacts of climate change and their effect on the variability of regional water resources has become a major concern. Better monitoring of water resources requires a thorough understanding of the relationships between hydrologic variability and ocean‐atmosphere dynamics. However, finding significant links between climate change and hydrologic variability has been a challenge for scientists. Oceanic indices and teleconnections explained by ocean‐atmosphere interactions, including the Southern Oscillation Index (SOI), Multivariate El Niño and Southern Oscillation Index (MEI), Pacific Decadal Oscillation (PDO), North Atlantic Oscillation index (NAO), Atlantic Multidecadal Oscillation (AMO), Pacific/North American index (PNA), and Madden‐Julian Oscillation (MJO), have raised significant attention within scientific communities to identify the most prominent climate signal as an indicator of abnormal climate conditions. This study identifies the relationships between these indices and major meteorological and hydrologic events in the central United States on the basis of their severity and spatial and temporal extents during the water years from 1950 to 1988. The Standardized Precipitation Index (SPI) and the Standardized Hydrology Index (SHI) are also utilized to identify regional climate and hydrologic responses to oceanic indices using a multivariate statistical analysis. The utility of the framework is then demonstrated by its application to forecasting seasonal streamflows in the Republican River Basin in southwestern Nebraska.

Select this Article		Different Approaches to Study the Adaptability of High‐Elevation Hydropower Systems to Climate Change: The Case of SMUD's Upper American River Project Kaveh Madani, Sebastian Vicuna, Jay Lund, John Dracup, and Larry Dale ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)372 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Two methods have been proposed to study the effects that climate change could have on the operations of high‐elevation hydropower facilities in California. In the first approach, a single regional hydropower system was modeled in detail in conventional volumetric units and in the second approach which was based on energy units more than 150 hydropower systems in the California Sierra Nevada were modeled in less detail. To find the advantages and disadvantages of the proposed methodologies, the developers of both method have teamed up to do a comparative study on the Sacramento Municipal Utility District's (SMUD) hydropower facilities. Better understanding of the differences and similarities of the two approaches makes it possible to more accurately extrapolate the impacts of climate change at the SMUD facility to other systems in California's Sierra Nevada. The results show great similarity between the proposed methods in terms of showing the changes in key variables such as energy generation and revenues. The limitations and advantages of both methods are also discussed.

back to top

COUPLED ATMOSPHERIC‐HYDROLOGIC PHYSICALLY‐BASED CLIMATE MODELS

Select this Article		A Regional Hydroclimate Model for Water Resources Management of the Tigris‐Euphrates Watershed Z. Q. Chen, Noriaki Ohara, Michael L. Anderson, and Jaeyoung Yoon ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)373 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract In order to establish a basin‐wide water management plan for the Tigris‐Euphrates (TE) watershed it is necessary to perform rigorous water balance studies of the whole watershed at least for critical historical drought and flood conditions, and under various water resources development scenarios. Performance of such water balance studies over the watershed requires climatic and hydrologic data sets, corresponding to historical critical flood and drought periods, at fine time and spatial grid resolutions in order to provide the necessary hydroclimatic information. Due to various political reasons in this region, such historical climatic and hydrologic data over this watershed are not available internationally at the desired fine time‐space coverage that is necessary for performing reliable water balance studies over the watershed. Reconstruction of such climatic and hydrologic data sets requires, a) the development of a regional hydroclimate model for the watershed in order to reconstruct the historical climatic and hydrologic data; and 2) the development of a hydrologic model in order to reconstruct the historical streamflows within the whole watershed. In order to downscale large scale atmospheric datasets over the Tigris‐Euphrates (TE) watershed and to reconstruct the above‐mentioned climatic and land hydrologic data sets, the nonhydrostatic Fifth Generation Mesoscale Atmospheric Model (MM5) of NCAR was coupled with the physically‐based land hydrologic component of Integrated Regional Scale Hydrologic‐Atmospheric Model (IRSHAM), and implemented to the TE watershed as its Regional Hydroclimate Model (RegHCM‐TE). Since snow is the main source of water for TE watershed, a physically‐based energy balance snow model was implemented to the watershed for the reconstruction of historical snowpack evolution and snowmelt processes. In order to route the flows and reconstruct historical streamflow data over the Tigris‐Euphrates river network, the HEC‐HMS (Hydrologic Modeling System) model was constructed over the watershed. Near the downstream end of Tigris‐Euphrates river network, a marshland hydrologic model was also developed for the Euphrates and Tigris marshlands. The RegHCM‐TE and the basin scale hydrologic model for Tigris‐Euphrates watershed will be described, and the reconstruction of historical climatic and hydrologic data over the watershed by means of these models will be presented.

Select this Article		Coupled Regional Scale Hydrologic‐Atmospheric Model with Spatially Horizontally Averaged Green‐Ampt Model Junichi Yoshitani and Z. Q. Chen ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)374 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A model, named Integrated Regional Scale Hydrologic/Atmospheric Model (IRSHAM), was developed. In IRSHAM a two‐way coupling scheme and areally‐averaged conservation equation are employed. This made long‐term realistic simulation possible on a regional scale. IRSHAM has a unique moisture flow component based on areally‐averaged Green‐Ampt equation to account for the heterogeneity of soils that can deal with wet initial conditions and with exfiltration. This soil moisture flow model was coupled with the boundary layer and 12‐layer mesoscale atmospheric models in a two‐way interaction.

Select this Article		Regional Modeling of Climate Change Impact on Peninsular Malaysia Water Resources Ahmad Jamalluddin bin Shaaban, Z. Q. Chen, N. Ohara, and M. Z. M. Amin ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)375 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The future projections of climate change by means of Global Climate Models (GCMs) of the Earth provide fundamental coarse‐grid‐resolution hydroclimate data for studies of the impact of climate change on water resources. We report on a study where the climate change simulations of Coupled Global Climate Model of the Canadian Center for Climate Modeling and Analysis were downscaled by a Regional Hydroclimate Model of Peninsular Malaysia to the scale of the subregions and watersheds of Peninsular Malaysia in order to assess the impact of future climate change on its water resources. Based on simulations of hydroclimatic conditions during the 1984–1993 historical and 2025–2034, 2041–2050 future periods it is concluded that the overall mean monthly streamflow is about the same during the future period and during the historical period for most of the watersheds except Kelantan and Pahang. In those two watersheds there is significant increase in the overall mean monthly streamflow during the future period. It is also clear that the high flow conditions will be magnified in Kelantan, Terengganu, Pahang and Perak River watersheds during the wet months, while low monthly flows will be significantly lower in Selangor and Klang watersheds during the dry months in the future.

back to top

FUTURE RESEARCH AND APPLICATION NEEDS OF RADAR RAINFALL DATA IN HYDROLOGY: PANEL DISCUSSION

Select this Article		Future Research and Application Needs of Radar Rainfall Data in Hydrology Baxter E. Vieux, Chandra S. Pathak, and Philip B. Bedient ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)376 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The hallmark of recent advances in radar precipitation estimates is the high resolution detection of spatially variable rainfall over large areas. Radar data far exceeds spatial densities of most rain gage networks and is useful for filling in the gaps between gage measurements. While radar provides the spatial and temporal patterns of rainfall, it requires correction or adjustment to remove systematic over‐ or underestimation of rainfall rates. Research in radar measurement of rainfall is needed to address the accurate conversion of reflectivity to rain rate, how radar system characteristics affect resolution and precision of the rainfall data, and improved methods for bias adjustment to remove systematic errors. First, we examine the origin and characteristics of radar estimation of rainfall, implementation of radar technology and algorithms, and then provide an overview of radar research needs in hydrology. Research and resulting advances in radar hardware and computer algorithms are expected to improve the use and reliability of radar information for civil infrastructure design and flood forecasting operations.

back to top

HYDROLOGIC MODELING: GENERAL

Select this Article		Calibration of Rainfall Runoff Models in Ungauged Catchments: Regionalization Relationships for a Rainfall Runoff Model Matthew S. Gibbs, Graeme C. Dandy, and Holger R. Maier ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)377 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract In many regions where rainfall runoff models are required, there is a lack of streamflow data available to calibrate the model parameters. Along with streamflow data simply not being recorded, there are many reasons for a lack of a suitable data set for model calibration, such as significant modifications to catchment characteristics, or long periods of unseasonable rainfall producing unrepresentative relationships. Generally, for an ungauged catchment, it is desirable to implement a model with as few free parameters as possible, provided the conceptualization of the model is suitable for the catchment under consideration. The Australian Water Balance Model (AWBM) is a rainfall runoff model that is commonly used in Australia. Typically it has 7 parameters, however methods are available to determine the storage size and capacity parameters for the AWBM based on an estimate of the average annual runoff. This is a great advantage when applying the model to ungauged catchments. However, there are two AWBM parameters which cannot be determined by this approach, namely the baseflow index and baseflow recession constant. The aim of this paper is to develop regionalization relationships to allow these two parameters to be estimated for ungauged catchments, based on the characteristics of the catchment that can be easily identified. General Regression Neural Networks are used to identify the relationships between model parameters and catchment characteristics. The results indicate that by using only easily identifiable characteristics of an ungauged catchment, suitable estimates of the unknown AWBM parameter values can be obtained, thereby allowing reasonable rainfall‐runoff models to be developed. While the relationships developed in this work are specific to Australian catchments, the methodology used can be easily adapted to develop relationships for other regions.

Select this Article		Development of a Robust Diffusion‐Kinematic Flow Algorithm for Regional Hydrologic Models Operating with Large Time Steps A. M. Wasantha Lal ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)378 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Diffusion flow models used to simulate hydrologic systems can become inaccurate under certain extreme flow conditions. Two such flow conditions include the relatively deep low slope flow condition as in the case of stagnant canals and the relatively shallow steep flow condition as in the case of mountain streams. In the case of relatively deep slow flows and short term simulations, the inertia effects are important, and full shallow water equations are needed to solve this problem. However, in the case of steep slopes, even if inertia terms can be neglected, long term simulations become problematic because of the need of fully implicit diffusion models to use small time steps when using kinematic flow. Many of the long term physically based hydrologic models for surface flow have to deal with meshes or cells when simulating irregular bottom slopes. These models need to trap water in deep ponds and pass water over steep slopes at the same time, creating conditions that are difficult to solve with models using only the diffusion flow approximation. Numerical methods that are stable with large time steps and small cells under both diffusion and kinematic flow conditions are needed in solving such problems. The current paper describes a stable computational approach that can be useful in solving both kinematic and diffusion problems. A fully implicit finite volume formulation of the approximate St. Venant equations is used in the formulation. Newton's method is applied to solve the nonlinear equation resulting from this approach. The paper demonstrates the stability and the boundedness of the approach when using very large time steps of the order of days.

Select this Article		Optimal Mesh Design for Groundwater Flow Models Based on Cost and Error Criteria A. M. Wasantha Lal ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)379 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Determining the spatial and temporal discretization is an important part of setting up a model. As a general rule for numerical models, the discretization has to be fine enough to show most of the details of the solution, but at the same time, it cannot be too fine to prevent excessive demand for run time and computer resources. In this paper, analytical expressions are obtained for optimal mesh size using the physical parameters of the governing ipartial differential equation (PDE), space and time scales under investigation, and run time constraints. The paper describes how sensitive the discretization is to each of the attributes around the optimum.

Select this Article		Statistical Methods and Representation of Extreme Discharge — Findings from a Distributed Hydrological Modelling Study Mark Henry Rubarenzya, Ph.D., M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)380 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract In the process of developing a physically‐based fully distributed hydrological model for the Grote Nete catchment in Belgium, it was desired to improve on the modelling of the extreme flows. To understand the relationship between river network representation and simulation output quality, a set of simulations was designed to investigate firstly, whether the representation of the Grote Laak River may be responsible for the difficulty in representing discharge conditions at Vorst; secondly, whether improved modeling of the flow hydrograph at Vorst would result in improved modelling of the peak flows at Varendonk; and thirdly, to obtain an understanding of the importance of river network modeling in a local versus a regional context. This paper presents the results of the multi‐site, multi‐criteria calibration protocol that was used in the model development process. This included both traditional goodness‐of‐fit statistics, and graphical comparisons of indicator variables. While the high discharge values were generally well simulated, some extreme high values were underestimated while some extreme low values were overestimated. This observation was investigated. The paper presents the findings of these analyses, including the results of studies into the importance of representation of river networks. The model has been successfully applied to understand the potential changes to discharge that would result from specific catchment‐scale anthropogenic changes.

Select this Article		Studying Effects of Spatial Scale on Model Calibration Using Soil Water Assessment Tool (SWAT) Sanjiv Kumar and Venkatesh Merwade ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)381 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Calibration of model parameters is a critical step in any successful watershed modeling project. The calibrated values of model parameters, however, are influenced by sub‐watershed divisions and resolution of input data. The objective of this research is to study the effects of sub‐watershed divisions and scale of soil data on calibration of SWAT model for the St. Joseph River Watershed (SJRW). Two sets of SJRW models one with SSURGO data (1:24,000 scale) and other with STATSGO data (1:250,000 scale), each set having six different level of sub‐watershed division varying from 10 sub‐watersheds to 97 sub‐watersheds, are independently calibrated using SCA‐UA algorithm for daily streamflow output at watershed outlet. Calibrated results show no significant difference in terms of model performance however good parameter sets showed varied range of sensitivity to model spatial scale. This result indicates towards redefining uncertainty range of sensitive model parameters.

back to top

IMPERVIOUS SURFACES I: DATA AND REMOTE SENSING

Select this Article		Historical Analysis of the Relationship of Streamflow Flashiness with Population Density, Imperviousness, and Percent Urban Land Cover in the Mid‐Atlantic Region S. Taylor Jarnagin ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)382 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Historical US Census population data was used to estimate population density for 1930–2000 and satellite imagery from circa 1973, 1992, and 2001 was used to estimate the degree of urban development and the percent imperviousness (for 1992 and 2001) for a set of 150 small (< 130 km²) watersheds with long‐term (> 20 years) USGS NWIS historical daily mean streamflow datasets in the mid‐Atlantic, USA. The Richards‐Baker Flashiness Index was used to calculate annual flashiness values and a seven‐year‐window mean stream flashiness value was calculated for each population/development estimation date. Streamflow stations that showed significant changes in historical flashiness had a higher mean population density than those that showed no change. The strength of the population‐flashiness correlation increased as the spatial scale of the population estimator was reduced. Urban development and imperviousness estimators were equally effective at exploring the relationship between stream flashiness and watershed development. Watersheds with less than 10% imperviousness and less than 20% ‘urban development’ displayed background levels of stream flashiness and mean flashiness increased with increasing imperviousness and urban development density thereafter.

Select this Article		Role of Watershed Size in Quantifying Imperviousness Tham Saravanapavan and Guoshun Zhang ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)383 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Imperviousness or Percent Imperviousness (PI) has been widely used in watershed management, especially in formulating storm water regulations and in simulating watershed hydrology in watershed models. Coefficient method is the widely used approach in quantifying watershed PI. In this approach, a unique imperviousness coefficient between 0 and 1 is assigned to each land use category. It is apparent that with the development of GIS technology, estimating impervious cover using the coefficient method is becoming a relatively easy task, especially for the users with limited technical capability. This paper demonstrates the importance of watershed size or scale in employing coefficient method to quantify watershed PI through an investigation of selected urban watersheds in Vermont. It also presents an important criterion in choosing the coefficient method to estimate PI as this method works well for large watersheds, but not for small watersheds. The results revealed that employing coefficient method to estimate PI for watersheds larger than 200 acres resulted in negligible error. In the mean time, employing coefficient method to watersheds with less than 50 acres in size resulted in substantial error. Although these conclusions are limited to the data presented in this study, the concept may be applicable to all data sets and geographical conditions.

back to top

MODELING OF LAND SURFACE HYDROLOGIC PROCESSES IN HYDROCLIMATE MODELING

Select this Article		Discrete Water Content Solution of the Infiltration Problem Fred L. Ogden, Ph.D., P.E., M. ASCE and Cary A. Talbot, P.E., M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)384 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Efficient and accurate simulation of the exchange between atmospheric, surface, and ground waters is essential in large‐scale hydro‐climatic models where high‐resolution computational grids are not practical. This objective is met with a new and innovative method for simulating the entry and redistribution of water in the vadose zone using a discrete water content solution. Unlike infiltration predictors such as the solution of Richards' equation or approximations thereof, our method employs a novel discretization in terms of water content. An explicit relationship is used to describe water movement in each discrete water‐content region of the pore space. Water is advanced according to capillary drive, and is re‐distributed according to the capillarity of each region of discrete water content. Evapotranspiration removes water from the profile according to a root distribution. The linear‐explicit nature of the computations provides for computational efficiency in both speed and the required resolution for numerical stability and accuracy. The finite volume solution methodology guarantees conservation of mass for all soil types and wetting front conditions.

Select this Article		Ensemble Averaged Flow Routing in Large Channel Networks: Kinematic Wave Equation I. Haltas, A. M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)385 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A new ensemble averaged kinematic wave equation is derived for the flow routing problem in large channel networks. The derivation is done by ensemble averaging the second‐order Taylor series expansion of the point scale kinematic wave equation around the mean value of the parameters of the concerned equation. Utilizing this ensemble averaged kinematic wave equation, ensemble averaged solution for the same ordered channels (according to Strahler‐Horton ordering) are obtained. Instead of solving each channel flow one by one, the ensemble averaged solution is computed for the ensemble of channels that are of the same order within the channel network. Ensemble averaging is only applied to the channel orders that include a sufficient number of channels to form an ensemble of adequate size. For channel orders that do not form an ensemble of adequate size, the standard solution method is followed. Using this methodology, the computational load and parameter data requirement are reduced substantially. Besides the obtained economy in computations and data requirement, this methodology also provides excellent results when compared to numerical solutions of the flows within the actual, detailed channel network.

Select this Article		Modeling of Land Surface Hydrologic Processes in Hydroclimate Modeling L. S. Kuchment ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)386 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The model suggested are based on the finite‐element schematization of river basins which is carried out taking into account the river basin topography, soils, land use, and vegetation and include the following main blocks: 1) a detailed description of snow processes and snow cover formation in the forest and at open areas, including change of the snow depth, content of ice and liquid water, snow density, snowmelt, snow interception, sublimation, re‐freezing melt water, snow metamorphism; 2) heat and moisture transfer in soil in cold periods including soil freezing and thawing, movement of the freezing front, and soil moisture transfer from the unfrozen layer of soil to the freezing front; 3) vertical heat and soil moisture transfer and evapotranspiration in the warm periods including the interaction between hydrological and carbon cycles in vegetation cover; 4) interaction between surface and groundwater; 5) overland, subsurface,ground flow; 6) channel flow (the Saint‐Venant equations; the advection‐diffusion equation; the kinematic wave equations). It is assumed that the snow water equivalent, the saturated hydraulic conductivity and the depth of frozen soil have subgrid stochastic variability and the ways of taking into account this variability have suggested. The structure of the models is chosen on the basis of results of sensitivity analysis and analysis of runoff generation mechanisms in given river basins. The part of parameters are the measured basin characteristics, several parameters are determined on the basis of empirical dependencies including the measured characteristics, and the rest of parameters are calibrated against runoff or other water balance component measurements. The model with some structural variations has been applied to data from more then 10 river basins with different phisiographic conditions including such large river as Vyatka, Kolyma, Seim. It has been showed that only 4–6 of most important parameters should be calibrated using comparatively short series of runoff measurements, whereas the values of the rest 10–12 parameters can be regionalized or assigned on the basis of empirical dependencies. Possibilities of using different empirical dependencies and transferability of these dependences and model parameters have been investigated. Numerical experiments have been carried out to test ability to apply the suggested physically based models of snowmelt runoff generation for the poorly gauged river basins.

Select this Article		Reconstruction of Historical Atmospheric Data for Mekong River Basin by a Hydroclimate Model N. Ohara, Z. Q. Chen, M. L. Kavvas, K. Fukami, and H. Inomata ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)387 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract In order to perform water balance studies over the Mekong river basin a historical atmospheric data set is needed over the basin at fine time and spatial grid resolutions as input to the watershed‐scale water balance models of the basin. Due to various reasons in this region, such historical atmospheric data over this region are not available at the desired fine time‐space scales. Consequently, it is necessary to utilize a regional coupled atmospheric‐hydrologic modeling technology in order to downscale the available historical global atmospheric databases that are at very coarse resolution (∼ 285km), to the Mekong river basin region at fine spatial resolution (∼ 20km). U.S. National Center for Atmospheric Research (NCAR) and U.S. National Center for Environmental Prediction (NCEP) have historical atmospheric data for the 1956–2006 period over the whole world at 2.5° latitude × 2.5° longitude spatial grid resolution and at 6‐hr time increments. However, over the Mekong basin, the 2.5° resolution corresponds approximately to 285 km. At such spatial resolution it is impossible to obtain the necessary spatial detail for the historical atmospheric conditions. Therefore, a regional, fully‐coupled atmospheric‐hydrologic hydroclimate model of Mekong basin, called “RegHCM‐Mekong” was developed at 20 km spatial grid resolution in order to accommodate the complex topographical and land surface features of this basin. RegHCM‐Mekong was then used to downscale the coarse time‐space resolution NCEP‐NCAR historical atmospheric data to produce 1‐hour‐increment meteorological information on rainfall, air temperature, specific humidity, wind velocity, solar radiation and net radiation at 0.2 degrees spatial resolution (about 20 km) over the whole Mekong basin during a historical period. The comparisons of RegHCM‐Mekong reconstructed historical rainfall fields in time and space against point‐location observations and against the spatial maps of historical precipitation observations yielded satisfactory results.

back to top

MULTI‐SENSOR RAINFALL ESTIMATION METHODS

Select this Article		Multiple Radar Data Merging in Hydro‐NEXRAD Witold F. Krajewski, Bong‐Chul Seo, Anton Kruger, Piotr Domaszczynski, Gabriele Villarini, and James A. Smith ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)388 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The Hydro‐NEXRAD merging algorithms include two options: (1) data‐based merging; and (2) product‐based merging. Data‐based merging algorithm takes volume scan reflectivity data from all radars involved through preprocessing algorithm that performs volume data quality control, interpolates data to synchronize temporal scale between individual radars, and finally combines data onto a common geographic grid. Reflectivity values for a given location are assigned by a weighting function with respect to the distance from the radar. This single reflectivity field is then converted to rainfall amounts using a user‐requested standard approach. In product‐based merging algorithm reflectivity data from multiple radars are all converted to rainfall using the same, user‐specified algorithm. These products are then combined into the final one using a weighting function that expresses the uncertainty of estimated rainfall amounts.

Select this Article		Multisensor Precipitation Estimation in the NOAA National Weather Service: Recent Advances David Kitzmiller, Feng Ding, Shucai Guan, David Riley, Mark Fresch, David Miller, Yu Zhang, and Guoxian Zhou ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)389 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The NOAA National Weather Service's current capabilities for producing real‐time, multisensor precipitation estimates have been focused on providing input to hydrologic prediction models for mainstem rivers and larger headwaters. New functions are now being implemented to produce analyses and short‐range forecasts for flash flood prediction operations, using a grid mesh of 1 km and a 5‐minute update cycle with minimal time lag. The functionality produces rainrate and rainfall analyses and forecasts from multiple radars, covering entire County Warning Areas. The characteristics of the new High‐resolution Precipitation Estimator and High‐resolution Precipitation Nowcaster and their output products are described below.

Select this Article		Radar Visualization and Data Exporter Tools to Support Interoperability and the Global Earth Observation System of Systems (GEOSS), from the National Oceanographic and Atmospheric Administration's (NOAA's) National Climatic Data Center (NCDC) Stephen Del Greco and Steven Ansari ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)390 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract In February 2005, 61 countries around the World agreed on a 10 year plan to build open systems for sharing geospatial data and services across different platforms worldwide. This system is known as the Global Earth Observation System of Systems (GEOSS). The objective of GEOSS focuses on easy access to environmental data and interoperability across different systems allowing participating countries to measure the “pulse” of the planet in an effort to advance society. In support of GEOSS goals, NOAA's National Climatic Data Center (NCDC) has developed radar visualization and data exporter tools using Open Source software libraries. The NCDC Interactive Radar Viewer and Data Exporter Toolkit load Weather Surveillance Radar 1988 Doppler (WSR‐88D) volume scan (S‐band) data, known as Level‐II, and derived products, known as Level‐III, into an OPEN Geographical Information System (GIS) compliant environment. The application is launched via Java Web Start and runs on the client machine while accessing these data remotely from the NCDC archive or in near real time from other NOAA servers. The Radar Interactive Viewer Toolkit provides custom data overlays, animations and basic queries. The export of images and movies is provided in multiple formats that support the “blending” of radar data with other types of data. The Data Exporter allows for data export in both vector polygon (Shapefile, Well‐Known Text) and raster (GeoTIFF, ESRI Grid, VTK, NetCDF, GrADS) formats. NCDC recently decoded Sigmet C‐band doppler radar data and plans to implement the functionality to read C‐Band radar data into the Radar Viewer/Data Exporter Toolkit. This supports a bilateral agreement between the United States and Canada for data sharing and interoperability. In addition, the NCDC is implementing decoders to read a test bed of distributed X‐ band radars that are funded through the Collaborative Adaptive Sensing of the Atmosphere (CASA) project. This paper describes in further detail the NCDC Radar Visualization and Data Exporter Tools, and the NCDC hopes to establish collaboration with scientists participating in GEOSS to leverage these tools for interoperable use with other global radar networks.

back to top

NEXRAD RAINFALL DATA ACCESS AND DATA QUALITY ISSUES

Select this Article		A Warm Season Radar QPE Algorithm Using Adaptive Z‐R Relationships Jian Zhang, Kenneth Howard, Xiaoyong Xu, and Carrie Langston ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)391 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Quantitative precipitation estimation (QPE) from radar is subject to errors including uncertainties in Z‐R relationships, contaminations from non‐precipitation targets, partial beam filling due to blockages, beam spreading, overshooting, etc. Among them inaccurate Z‐R relationship is one of the most significant errors. An accurate Z‐R relationship should correctly represent spatial and temporal variations of the microphysical processes and associated drop size distributions in the observed precipitation system. However, most of existing operational radar QPEs use single Z‐R relationship for the whole radar coverage area. This paper presents an algorithm that identifies different microphysical processes in warm season precipitation systems using three‐dimensional radar reflectivity structure and environmental thermal field. Precipitation echoes are segregated into convective, stratiform, hail, and warm rain regimes and corresponding Z‐R relationships are applied. The scheme was tested for events from several regions in the United States and was shown to provide improvements over single Z‐R approaches. The scheme is fully automated and can be potentially used for operations.

Select this Article		Effect of Areal Averaging on Gauge‐Radar Comparison Hatim Sharif, M. ASCE, P.E., Fred L. Ogden, M. ASCE, P.E., and Edward Brandes ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)392 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Several issues related to areal averaging of radar estimates and their use in gauge‐radar and radar bias adjustment are addressed. A precise method for averaging radar estimates is presented. Comparison estimates using this method and estimates by an approximate method reveals that there can be significant differences. The effect of precise averaging was more pronounced for the S‐POL 150 m gate spacing radar data relative to 1 km gate spacing WSR‐88D data. Data from two field experiments were analyzed and gauge‐radar comparisons were performed. The main steps of the WSR‐88D Precipitation Processing System (PPS) adjustment are simulated for an extreme event using areally radar estimates and estimated from the collocated radar bin. Given that areally averaged radar estimates are comparably correlated with gauge estimates, they can be used in the PPS adjustment with confidence.

Select this Article		Hydro‐NEXRAD: An Updated Overview and Metadata Analysis Witold F. Krajewski, Anton Kruger, Piotr Domaszczynski, Charles Gunyon, Bong Chul Seo, Radosław Goska, James A. Smith, Mary Lynn Beack, and Matthias Steiner ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)393 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Hydro‐NEXRAD is a prototype system that allows hydrologists to obtain user‐specified rainfall data for their research. These data are based on observations collected by the national network of WSR‐88D radars, known as NEXRAD. Users interact with Hydro‐NEXRAD through a web‐based interface that has map‐based components for spatial navigation, calendar‐ and time series plot components for temporal navigation and a menu‐based component for selection of processing options. Through the interface, users browse the Hydro‐NEXRAD metadata and select data of interest. As the system is approaching the point of being fully operational, the authors and a group of test users have evaluated several aspects of the system. Metadata remains very important for the system functionality. Radar‐based, basin‐based and point (for selected set of rain gauge locations) metadata serve multiple purposes: 1) enable users to efficiently search for subsets of data (SQL query, visual inspection), 2) provide information on quality of the collected data archive (missing or corrupt data), 3) and have a scientific value (basin‐based metadata has a potential to be used as a precipitation input to hydrologic models). The authors provide an updated overview of the Hydro‐NEXRAD system. Additionally, the authors present the complete set of Hydro‐NEXRAD metadata and discuss their possible applications.

back to top

NEXRAD RAINFALL DATA APPLICATIONS IN HYDROLOGIC AND HYDRAULIC MODELING

Select this Article		Floodplain Map Library (FPML): Innovative Method for Flood Warning System for Urban Watersheds in Houston, TX Z. Fang and P. B. Bedient ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)394 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The next step in the development of flood warning systems aims to provide visualized information on floodplain inundation maps in addition to predicting hydrographs at various points in real time. The normal approach to this goal follows rainfall transformation and floodplain delineation using both a calibrated hydrologic model and an accurate hydraulic model (HEC‐RAS) in real time. The hydrologic model (HEC‐1) has been run for many years without problems in real time, but the standardized hydraulic model (HEC‐RAS) has difficulty in handling large and intense hydraulic computation in real time. Because bridges can create serious problems with numerical instability in real‐time applications, it is especially difficult for HEC‐RAS to simulate elevations where numerous bridges can overtop during a major flood. In order to approach the goal of visualizing floodplains, the floodplain map library (FPML) as a new hydraulic prediction tool has been developed for White Oak, one of the major urban watersheds in Houston. The similar methodology was used to develop the Brays Bayou FPML, which is currently being created and integrated into an existing radar‐based flood alert system (FAS2) for the Texas Medical Center (TMC) in Houston to provide inundation maps in near real time. The development of FPML includes three stages: designing rainfall patterns based on historical rainfall data over the watersheds, delineating 99 floodplain maps in Geographic Information System (GIS) based on design rainfalls for each watershed, and designing an algorithm to link real‐time NEXRAD radar rainfall to the appropriate map. The FPML system can analyze rainfall intensities and patterns to quantify water surface elevations and delineate floodplains under various spatial and temporal conditions. This will allow the emergency personnel to begin flood preparation with as much lead time as possible, and the enhanced system can be used as a prototype for other flood‐prone areas along the Gulf coast. The FPML method is also compatible with storm surge model outputs in order to predict inundation maps and evaluate severe inundation in non storm surge zones. For example, major evacuation routes from Galveston can be visualized during extreme coastal weather conditions. The FPML with storm surge data will improve emergency personnel's ability to initiate evacuation strategies at many levels.

Select this Article		Fusible Polyvinylchloride Pipe: Water and Wastewater Infrastructure Construction and Rehabilitation Redefined Richard (Bo) Botteicher, P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)395 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The development of fusible polyvinylchloride pipe with fully restrained, gasketless, thermally butt‐fused joints creates a pipe system that has the same strength at the joint as the rest of the pipe. This pipe and joining technology create a fully monolithic system that can be used in conventional direct bury installations as well as cutting edge trenchless applications; including horizontal directional drilling (HDD), sliplining and pipe bursting. This technology offers some unique alternate solutions to the ongoing concerns of aging water and wastewater infrastructure, life cycle costs of new and rehabilitation installations, and installations within constrained project sites. This paper will focus on the specific technology for this type of jointing of PVC pipe and document the benefits and considerations of this technology for use in the water and wastewater industries. A recent project case study that has utilized this technology will also be reviewed.

Select this Article		Radar‐Based Flood Forecasting: Quantifying Hydrologic Prediction Uncertainty in Urban‐Scale Catchments for CASA Radar Deployment B. E. Vieux, J. M. Imgarten, J. P. Looper, and P. B. Bedient ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)396 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Stormwater runoff significantly impacts flooding and water quality in urban areas. Prediction of the runoff response in urban catchments requires accurate and representative rainfall over catchments that are composed of natural and man‐made drainage networks and surfaces. The spatio‐temporal variability of rainfall and the hydraulic drainage network and catchment characteristics combine to produce the runoff response to storm events. Whether the storm event is characterized by convective, stratiform, or tropical rainfall processes the combination of radar and gauge observations can be used to make hydrologic predictions in real‐time. Archival gauge‐adjusted radar rainfall is used as input to a distributed model with detailed representation of the catchment. Results show that peak stage can be estimated with an accuracy of 1.05 ft RMSE and timing for the simulated events excluding the outliers of 10.0 min RMSE.

back to top

NEXRAD RAINFALL DATA APPLICATIONS IN HYDROLOGY

Select this Article		On the Use of Rainfall Remote Sensing Information in Hydrologic Modeling: Data Accuracy Assessment and Potential Improvements Boone F. Larson, Emad Habib, Jeffrey Graschel, and Brian R. Nelson ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)397 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract This study focuses on validation assessment of accuracy of rainfall remote sensing information for improving hydrologic predictions. The multi‐sensor precipitation products (MPE) of the National Weather Service (NWS) River Forecast Centers (RFC) are considered in this study. Multi‐sensor data is provided at hourly temporal resolution and over a national Hydrologic Rainfall Analysis Project (HRAP) grid having a nominal size of 4 square kilometers. The analysis was done over a three‐year period (2004–2006) using 13 independently operated rain gauges located within an area of ∼30 km² in south Louisiana. The study will examine the impact of MPE uncertainties on runoff simulations in a mid‐size experimental watershed in south Louisiana. The physically‐based hydrologic model (Gridded Surface Subsurface Hydrologic Analysis, GSSHA) will be driven by two scenarios of rainfall forcing: rainfall data from a dense gauge network over the watershed, which represents a rather ideal scenario of rainfall sampling, and finally rainfall data from MPE products. Differences between MPE and dense gauge simulations will shed light on uncertainties in MPE and their impact on runoff predictions. The study will have implications for validation of multi‐sensor estimates as a technique for improvement of radar‐gauge merging algorithms and further enhancing accuracy of hydrologic forecasting.

Select this Article		Use of Czech Weather Radar Network Data for Precipitation Estimating and Nowcasting Petr Novák and Zbyněk Sokol ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)398 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The Czech weather radar network (CZRAD) is operated by the Czech Hydrometeorological Institute (national weather service of the Czech Republic). CZRAD data are used for severe weather and precipitation monitoring by national civil and military weather services, operational hydrology, air traffic control and many other users including general public. Several damaging floods, which hit the Czech Republic in last decade, emphasized importance of radar data for hydrological applications and accelerated research and development in the field of rainfall estimating and nowcasting. The development of the methods is performed in cooperation with the Institute of Atmospheric Physics (Czech Academy of Sciences) and US National Weather Service (US NWS). The paper presents the Czech weather radar network and operational implementations of radar based quantitative precipitation estimates (QPE) and forecast (QPF) methods. Status of the current development and future outlook is also discussed.

back to top

POSTER SESSION IV: SURFACE WATER HYDROLOGY

Select this Article		Improving Forecasts of Flood Risk by Incorporating Climate Variability into Bulletin 17B LP3 Model Ashwini S. Kashelikar and Veronica W. Griffis ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)399 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The current techniques for flood frequency analysis presented in Bulletin 17B assume annual maximum floods are stationary; meaning the distribution of flood flows is not significantly affected by climatic trends or long‐term cycles (i.e. decadal variations). In light of growing evidence that streamflows are nonstationary and are impacted by climate variability, Bulletin 17B techniques should be modified. The effects of climatic cycles occurring over a shorter time frame, such as El Niño‐Southern Oscillation (ENSO), are averaged into flood risk estimates obtained using the procedures of Bulletin 17B. However, the effects of ENSO are likely to affect the magnitude of annual maximum streamflows, and thus would impact flood risk in a given year. Estimates/forecasts obtained using the Bulletin 17B LP3 model can be improved by incorporating the effects of climate variability associated with ENSO events into updated estimates of the mean, and perhaps the standard deviation, by regressing the LP3 parameters on a climatic index such as sea surface temperature anomalies. In this study, a regression model is applied to annual maximum streamflow records for unimpaired gauging stations across the contiguous United States to obtain a one‐year ahead forecast of the mean. For stations where the regression analysis yields significant results, the forecasted flood risk is compared with estimates obtained using the existing Bulletin 17B LP3 model.

Select this Article		Propagating Uncertainty in Climate Data for Hydrologic Prediction Shivam Tripathi and Rao S. Govindaraju ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)400 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Understanding the impact of climate change and its variability on regional hydrology is predicated, to a large extent, on availability of long records of high quality climate data. Although recent advances in satellite technology have improved our observation capabilities, past records come from traditional in situ measurements that have large associated uncertainties. Further, the uncertainties in historical observations vary significantly over space and in time. The information on uncertainty that is available with latest datasets is vastly ignored in the hydrologic literature. Since any relationship linking hydrologic and climatic variables is underpinned by historical data, ignoring this uncertainty information can be misleading. In this study, a methodology is developed to incorporate the observation, uncertainty in climate data for hydrologic prediction by combining Bayesian learning theory and the concepts of robust optimization. A Bayesian variant of principal component analysis is used to propagate uncertainties in observations to derive a new representation of data with reduced dimensionality. Robust optimization is then used to obtain the parameters of the prediction model, a linear support vector machine in this case, by accounting for the uncertainty in data representation. The developed methodology is applied to make long‐range prediction of Indian summer monsoon rainfall (ISMR) by capturing dynamic relationships between ISMR and sea surface temperature. The advantages of incorporating observation uncertainties for hydrologic predictions are discussed in the light of results obtained.

back to top

RAINFALL DATA ESTIMATION

Select this Article		A Spatial‐Temporal Statistical Downscaling Approach to Estimation of Extreme Precipitations for Climate‐Related Impact Studies at a Local Site V. T. V. Nguyen and T. D. Nguyen ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)401 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract This paper presents a spatial‐temporal downscaling approach to describe the linkage between large‐scale climate variables for daily scale to annual maximum (AM) precipitations for daily and sub‐daily scales at a local site. The proposed approach is based on a combination of a spatial downscaling method to link large‐scale climate variables as provided by General Circulation Model (GCM) simulations with daily extreme precipitations at a local site and a temporal downscaling procedure to describe the relationships between daily extreme precipitations with sub‐daily extreme precipitations using the scaling General Extreme Value (GEV) distribution. The feasibility of the proposed downscaling method has been tested based on climate simulation outputs from two GCMs under the A2 scenario (HadCM3A2 and CGCM2A2) and using available AM precipitation data for durations ranging from 5 minutes to 1 day at 15 raingage stations in Quebec (Canada) for the 1961–1990 period. Results of this numerical application has indicated that it is feasible to link large‐scale climate predictors for daily scale given by GCM simulation outputs with daily and sub‐daily AM precipitations at a local site. Furthermore, it was found that AM precipitations at a local site downscaled from the HadCM3A2 displayed a small change in the future, while those values estimated from the CGCM2A2 indicated a large increasing trend for future periods.

Select this Article		Optimal Spatial Weighting Methods for Estimation of Missing Rain Gage Records Ramesh S. V. Teegavarapu and Pankaj Bajaj ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)402 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Deterministic and stochastic weighting methods are the most frequently used methods for estimating missing rainfall values at a gage based on values recorded at all other available recording gages. Distance‐based weighting methods suffer from one major conceptual limitation based on the fact that Euclidian distance is not always a definitive measure of the correlation among spatial point measurements. Several spatial weighting methods are proposed, developed and investigated for estimation of missing precipitation records. These methods use mathematical programming formulations and evolutionary algorithms. Historical daily precipitation data obtained from 15 rain gauging stations from a temperate and semi‐arid climatic region are used to test and derive conclusions about the efficacy these of methods. Results suggest that the weights derived based on mathematical programming formulations and surrogate parameters for correlations are superior to those obtained from scalar distance‐based weights used in spatial interpolation methods for estimation of missing rainfall data at points of interest.

back to top

SPACE‐TIME ANALYSIS OF NEXRAD RAINFALL DATA

Select this Article		Analysis of 5‐Years of WSR‐88D Data over the Mississippi River Basin Fred L. Ogden, Ph.D., P.E., M. ASCE and Michael J. Rogalus, III ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)403 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract We analyzed WSR‐88D radar‐rainfall estimates over the Mississippi River Basin for the period 1996–2000 at the time scale of individual events using data from over 900 rain gages that were not used in real‐time adjustment of the rain rate estimates. In this paper we present an evaluation of a radar‐rainfall dataset produced for the Global‐Continental scale International Project (GCIP). The GCIP data were adjusted using a tuned Z‐R relation to improve performance at the time scale of individual storms. Correlation between rain gage observations and the radar‐rainfall estimates were computed for each RFC over the period of record analyzed. Large geographical difference in the accuracy of weather‐radar rainfall estimates were quantified. Results indicate that primary indicators of radar‐rainfall estimation accuracy are the number of overlapping radars, distance from radar to gage, and elevation of the gage.

Select this Article		Geo‐Spatial Comparison of Rain Gauge and NEXRAD Data for Central and South Florida Chandra S. Pathak and Baxter E. Vieux ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)404 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The South Florida Water Management District (District) is responsible for managing water resources in 16‐counties over a 46,439‐square kilometer (17,930 square‐mile) area. The area extends from Orlando to Key West and from the Gulf Coast to the Atlantic Ocean and contains the country's second largest lake — Lake Okeechobee and the world famous Everglades wetlands. The District operates approximately 3,000 kilometers (∼1,800 miles) of canals, 22 major pump stations and 200 water control structures. Near‐real‐time rainfall data are used in operation of these pumps and water control structures. The District uses a network of approximately 287 active rain gauge stations that cover the more populated and environmentally sensitive areas under its management and provide data for this purpose. Four NEXRAD (Next Generation Weather Radar) sites operated by the National Weather Service cover the region. Since 2002 the District began to acquire NEXRAD data coverage. Corporate access of 15‐minute, rain gauge‐adjusted NEXRAD data, for each of the 2 × 2 km cells in the grid covering the District, was a major objective of the acquisition. The District has been receiving the NEXRAD data two types of datasets — near‐real time (NRT) and end‐of‐month (EOM). District is using ArcIMS based application for NEXRAD data retrieval. The application provides varied spatially and temporally integrated datasets in tabular and image formats. This paper compares results of geo‐spatial analysis of clusters of rain gauge and NEXRAD data. The data used in the analysis includes rain gauge data and the NEXRAD rainfall data that was collected during 1995–2005 at 2 × 2 km resolution. A set of clusters of rain gauges and a regular array of analysis blocks that were 20 × 20 km in size for the NEXRAD data were used to account for variability of the rainfall processes and local rainfall patterns. The spatial autocorrelations of the rain gauge and NEXRAD rainfall were identified using a semivariogram approach at daily timescale. The model fitting to the semivariograms were performed on data from 1998–2005. The range parameter of the semivariograms from rain gauge and NEXRAD rainfall data sets were compared.

Select this Article		Improvement of NEXRAD Rainfall Data for Central and South Florida Chandra S. Pathak and Baxter E. Vieux ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)405 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The South Florida Water Management District (District) is responsible for managing water resources in 16‐counties over a 46,439‐square kilometer (17,930 square‐mile) area. The area extends from Orlando to Key West and from the Gulf Coast to the Atlantic Ocean and contains the country's second largest lake — Lake Okeechobee and the world famous Everglades wetlands. The District operates approximately 3,000 kilometers (∼1,800 miles) of canals and over 500 water control structures. Near‐real‐time NEXRAD rainfall data and rain gage network is used to manage water resources in South Florida. The District uses a network of approximately 287 active rain gage stations that cover the more populated and environmentally sensitive areas. Five NEXRAD (Next Generation Weather Radar) sites operated by the National Weather Service cover the region. In conjunction with three of the other five water management districts in Florida, the District has acquired processed radar data from OneRain (formerly NEXRAIN Corporation) since July 2002. The 15‐minute radar rainfall data was derived from the 2‐km × 2‐km high‐resolution precipitation product, which was produced from NWS Level 3 — NEXRAD reflectivity. To achieve improved accuracy, gage‐adjusted radar rainfall data were derived. This paper provides details on improvements that were made to existing radar rainfall data processed and provided for the District. A bias correction methodology was identified to improve data quality and accuracy in the existing radar rainfall data. The method was applied to existing rainfall data and its performance evaluated and assessed. The improvement obtained through reprocessing the existing radar rainfall data was summarized through data comparison of annual totals and by comparison to gage accumulations over the three watershed areas. In addition, Level 2 NEXRAD reflectivity data (also 2‐km × 2‐km)from surrounding radars were processed to estimate radar rainfall data using a standard Z‐R relationship. During a validation event, the radar rainfall data derived from Level 2 produced better agreement and more accurate rainfall than either the existing radar rainfall product or the reprocessed data. The NEXRAD data quality improvement process performed in this study increased the amount of rainfall through application of the spatially variable bias correction, produced more consistent results through verification at control gages using statistical performance measures.

Select this Article		Infilling of Rain Gage Records Using Radar (NEXRAD) Data: Influence of Spatial and Temporal Variability of Rainfall Processes Ramesh S. V. Teegavarapu and Chandra Pathak ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)406 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Deterministic and stochastic weighting methods are the most frequently used methods for infilling rainfall values at a gage based on values recorded at all other available recording gages or other sources. Radar (NEXRAD) data is also commonly used for infilling of rainfall data. Several issues that affect the infilling methods include: the historical rain gage and radar data, spatial and temporal variability of rainfall, radar‐rain gage relationships, selection of spatial extent of radar data. The current study evaluates the influence of spatial and temporal variability of rainfall processes on the performance of spatial interpolation algorithms. Seasonal variation of rainfall, rainfall areas that are delineated based on physical processes affecting the genesis and morphology of rainfall processes, and other factors may affect the performance of infilling methods. All these issues are important for south Florida which experiences wide variability in rainfall in space and time. In the current study, data from several rain gages and radar (NEXRAD) data in the south Florida region are used to evaluate the influence of spatial and temporal variability of rainfall processes on the performance of methods used for infilling rain gage data.

back to top

STATISTICAL/STOCHASTIC MODELING APPROACHES TO HYDROCLIMATE

Select this Article		A Statistical/Stochastic Model of the Hydroclimate System M. L. Anderson, Ph.D., P.E., M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)407 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The hydroclimate system is a nonlinear, dynamic system with multiple feedbacks and interactions. The time evolution of this complex system seemingly defies deterministic description. An alternative model presented here considers the concept of a climate probability distribution function (climate pdf). The climate pdf is a probabilistic description of some element of the hydroclimate system that is based on the physics of the system. It can change with time and contains all physically possible outcomes for a given location. It can be estimated through the use of observations, Monte Carlo simulations, or through solution of a system of stochastic partial differential equations. Conditional climate pdfs associated with hydroclimate phenomena such as El Nino/Southern Oscillation (ENSO) can also be constructed. Climate pdfs and conditional climate pdfs can be used in hydrologic engineering applications. An overview of this statistical model of the hydroclimate system and an example application are presented in this paper.

Select this Article		Incorporating Antecedent Soil Moisture into Streamflow Forecasting within the North Platte River Basin, Wyoming Cody L. Moser, Tyrel L. Soukup, Glenn A. Tootle, and Greg L. Kerr ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)408 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A study of incorporating soil moisture into forecasting streamflow volumes within the Wyoming North Platte River Basin is presented. Current NRCS forecasting methods are replicated and a comparison is drawn between current NRCS forecasts and the proposed forecasting methods. Current predictors used in regression based streamflow forecasting are precipitation, antecedent streamflow and snow water equivalent from SNOTEL (snow telemetry) sites. Proposed methods include extending the forecast period and adding soil moisture as a predictor variable. An expert system is utilized to segregate data based on antecedent soil moisture conditions. Correlation techniques combined with principal component analysis and stepwise regression are applied to determine ideal predictor locations and to generate validation statistics that illustrate improved forecasting ability through the implementation of antecedent soil moisture as a predictor variable.

Select this Article		Simple and Multiple Change Point Detection in Multiple Linear Regression and Application to Hydroclimatic Variables T. B. M. J. Ouarda and O. Seidou ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)409 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Two Bayesian methods of changepoint detection in multivariate linear regression are proposed. The first approach allows simultaneous single changepoint detection in a multivariate sample. It improves on recently published changepoint detection methodologies by allowing a more flexible prior specification for the existence of a change, the date of change and for the regression parameters. The estimation of parameters is achieved by MCMC simulations. The second approach is a multiple changepoint detection model in multivariate linear regression. A new class of priors for the parameters of the multivariate linear model is introduced and useful formulas are derived that permit straightforward computation of the posterior distribution of the changepoints. The second method is numerically efficient and does not involve MCMC simulation. It allows fast simulation of the probability of each possible number of changepoints and the posterior probability distribution of each changepoint conditional on the number of changes.

Select this Article		The Stochastic Upscaling of One‐Dimensional Unconfined Groundwater Flow Mesut Cayar ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)410 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A new upscaling model for unconfined groundwater flow is proposed from a point‐location‐scale equation to a scale of computational grid areas. The developed evolution equation for the probabilistic behavior results from random variations in hydraulic conductivity, and the nonlinear stochastic unconfined flow process becomes a mixed Lagrangian‐Eulerian Fokker‐Planck equation (FPE). Furthermore, the FPE is a deterministic, linear PDE and has the advantage of providing the probabilistic solution in the form of evolutionary probability density functions. Subsequently, the Boussinesq equation for one‐dimensional unconfined groundwater flow is converted into a nonlinear ordinary differential equation (ODE) and a two‐point boundary value problem through the Boltzmann transformation. The resulting nonlinear ODE is converted to the FPE by means of master key ensemble average conservation equations. The numerical solutions of the FPE are validated with Monte Carlo simulations under varying stochastic hydraulic conductivity fields. Results from the model application to groundwater flow in heterogeneous unconfined aquifers illustrate that the time‐space behavior of the mean and variance of the hydraulic head are in good agreement for both the stochastic model and the Monte Carlo solutions. This indicates that the derived FPE, as a stochastic model of unconfined groundwater flow, can express the spatial variability of the unconfined groundwater flow process in heterogeneous aquifers adequately.

back to top

UNCERTAINTY IN RADAR RAINFALL ESTIMATES

Select this Article		Assessing Gauge Adjusted Radar Rainfall Estimation for Use in Local Flash Flood Prediction Beth Clarke, Chad Kudym, and Angie Albers ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)411 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The Urban Drainage and Flood Control District (UDFCD) operates a Flash Flood Prediction (FFP) Program, to forecast rainfall events up to 24 hours in advance within the Denver Metropolitan Area (Figure 1). Program meteorologists from the private sector communicate directly with local governments to prepare for and assess flash flood threats. Spatially comprehensive rainfall estimates that are both timely and accurate are critical in this mission. As part of the FFP program, UDFCD maintains an ALERT gauging network, for real‐time monitoring of rainfall. Weather Decision Technologies (WDT) Inc. provides UDFCD with rainfall estimates in real‐time that are automatically derived from NEXRAD Level II mosaicked radar data. The WDT rainfall estimates are derived on a CONUS scale, 'clipped' and then adjusted using the ALERT rain gauge data (Figure 2). The WDT rainfall data are provided in Geographic Information System (GIS) format on a high‐resolution 1 km grid. Traditionally, meteorologists for UDFCD have used, coarser resolution, NWS single site radar data in conjunction with their point ALERT data to estimate basin rainfall and communicate the potential flash flood threat with local agencies. During the 2007 program, WDT integrated the ALERT rain gauge data into their high resolution gridded radar rainfall mosaics, updated every 15 minutes. WDT provided both the radar‐only Quantitative Precipitation Estimates (QPE) using multiple radars and the gauge‐adjusted QPE products (QPE_GC) at 1 km resolution in real‐time. Significant rainfall events were archived over the 2007 season. Observations of 24‐hour rainfall from the Community Collaborative Rain Hail and Snow (CoCoRaHS) database provided a dense network of independent rain gauge data to perform statistical assessment of gauge adjusted QPE products on a daily basis. The National Weather Service 24‐hour precipitation analysis is used as a baseline comparison to measure the performance of the WDT QPE against. This paper will discuss the gauge‐adjusted radar QPE techniques, the integration of QPE products in local flash flood prediction processes and verification of the rainfall estimates for cases from the 2007 season.

Select this Article		Estimation of Radar Calibration Uncertainties Related to the Spatial Variability of Rainfall within a Single Radar Pixel — Statistical Analysis of Rainfall Data from a Dense Network of Rain Gauges Lisbeth Pedersen, Niels Einar Jensen, and Henrik Madsen ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)412 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A total of 6 months of rainfall data sampled with nine rain gauges on a 500 × 500 meter area has been analysed in order to determine the variability of rainfall within such a small area. The area corresponds to that of a maximum pixel size of a Local Area Weather Radar (LAWR). To calibrate a LAWR, the rain depth from a number of events is used and the analysis is therefore carried out on a total of 29 events fulfilling certain criteria's. The variability is expressed with the coefficient of variation and found to vary from 3 % to 100 % depending on type of rainfall. This gives an uncertainty in that range if a post event specific calibration is performed with a single rain gauge.

Select this Article		Evaluation of Functional Forms of Rain Gage — Radar (NEXRAD) Data Relationships Ramesh S. V. Teegavarapu, Delroy Peters, and Chandra Pathak ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)413 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The use of radar (NEXRAD) estimated rainfall data for providing information about the extreme rainfall amounts resulting from storms, hurricanes and tropical depressions is common today. Often corrections are applied to the RADAR generated rainfall data‐based on what was actually measured on the ground by rain gages. Understanding and modeling the relationships between RADAR and rain gage data are essential tasks to confirm the accuracy and reliability of the former surrogate method of rainfall measurement. Conventional regression models are often used to capture these highly variant non‐linear spatial and temporal relationships. This study aims to understand and model the relationships between radar (NEXRAD) estimated rainfall data and the data measured by conventional rain gages. This study proposes to investigate the use of emerging computational data modeling (inductive) techniques and develop optimal functional approximation methods for this purpose. The radar based rainfall data and rain gage data will also be analyzed to understand spatio‐temporal associations. The study areas selected from upper and lower Kissimmee basins of south Florida form the test‐bed for the proposed approaches and ensure the testing of the validity and operational applicability of these approaches.

back to top

CHALLENGES TO SUSTAINABLE DESIGN, POSSIBLE SOLUTIONS

Select this Article		Grey Water Use as a Water Management Option in Las Vegas, Nevada Sajjad Ahmad, Ph.D., P.E. and Zachary Hills ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)414 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Southern Nevada, located in the southwestern region of the United States has forecasted increases in water demands and limited water resources. Incentives have been implemented by the Southern Nevada Water Authority (SNWA) to encourage residents to reduce residential outdoor use. As the residential outdoor use campaign becomes exhausted, additional policies should be considered. The idea of grey water reuse to reduce fresh water residential outdoor use is investigated. A dynamic simulation model using system dynamics modeling approach is developed. A policy requiring all future development (beginning in the year 2008) in southern Nevada to divert a portion of used indoor water to supplement outdoor use is evaluated. This policy reduces the water withdrawn from Lake Mead resulting in reduction in back and forth transport of water to and from Lake Mead, but it also reduces the return‐flow credits. Energy consumption (pumping and treating) decreases, energy extraction (in the Las Vegas Wash) decreases, infrastructure expansion rates decrease for both potable and wastewater facilities, and losses due to evapotranspiration decrease because less water is being exposed to the atmosphere. The model shows that if 40 gpcd of indoor water used (grey water) is diverted for outdoors use, 2.28 10⁴ million gallons per year (70,000 acre feet) of water savings can be achieved by the year 2035 and $6.3 million per year pumping costs can be saved. To address environmental and public health concerns purple piping for grey water reuse systems should be used and monitoring wells should be installed.

Select this Article		Pacific Rim Indigeneity and Sustainable Municipalities Te Kipa Kepa Brian Morgan ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)415 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Pacific Rim communities face a plethora of challenges associated with sustainability. Addressing the water, transportation and energy requirements of communities that have ever increasing concern for land, air and water pollution, sea‐level rise, changing weather patterns and extremes, is a complex challenge for engineering analysis. With an increasing emphasis on broader stakeholder input, engineers are now also required to take into account social and cultural impacts. The challenge of integrating indigeneity and sustainability are discussed in this paper, and a new decision making framework for sustainability assessment is presented. A case study is provided to demonstrate the approach used by the Mauri Model, and although it has been developed for the specific context of sustainability assessment in Aotearoa New Zealand, this paper concludes that the decision making framework may be readily adaptable for all Pacific Ocean and Pacific Rim commuities.

back to top

ENGINEERING A SUSTAINABLE FUTURE

Select this Article		Sustainable Energy Solutions and a World Class River George M. Waldow, P.E. and Douglas A. Spaulding, P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)416 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract As sustainable energy generation becomes increasingly important, the role of hydroelectric power will continue to expand. However, this expansion must occur in a well‐reasoned and balanced manner to be fully compatible with enlightened contemporary values. Federal licensing of four hydroelectric facilities (two existing and two proposed) in an historic urban reach of the Mississippi River required many years of effort. The process involved numerous political jurisdictions, many resource management agencies and a broad range of stakeholders. In each case, the license applicant had to demonstrate that future hydroelectric operations would be fully compatible with the multiple authorized uses of the river corridor — and would not have objectionable environmental or social consequences. The diverse issues and concerns that were raised addressed to achieve the required degree of compatibility, may be of interest to others involved in the quest for sustainable energy solutions.

Select this Article		Water Conservation on the Supply Side, Using Underground Water Storage Systems Stanley R. Peters, P.E., M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)417 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract With continuing population increases, society's demands for water will also increase. Most governmental agencies are expanding their consumer-based water conservation programs, as an important way of meeting these increased, future demands. With global warming increasing evaporation rates, avoiding evaporative losses with future water storage projects is also a significant step in “supply-side”, water conservation. Evaporative losses from surface water storage reservoirs are function of local evaporative rates and the reservoir's effective depth. Based on this study, approximately 20% additional surface storage capacity would be required to account for the evaporative losses throughout these fourteen states. Avoiding evaporative losses by storing water underground can be accomplished by a variety of traditional methods, as well as a new method of underground water storage.

Select this Article		Sustaining Adequate Public Water Supply: The Challenges Ahead William E. Cox ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)418 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Public water supply is an essential service traditionally given a high priority in the United States, but sustaining adequate supply will confront a variety of future challenges. All the traditional challenges remain and continue to intensify, including the difficulties of balancing supply and demand in an environment of increasing water scarcity; protecting water supplies from an ever‐expanding range of potential contaminants and activities; and maintaining adequate managerial capacity for necessary planning, investing in required facilities, and conducting operations. The challenges of the future will also include non‐traditional concerns such as the threat of terrorism directed toward water supplies and climate change that may adversely impact existing supplies as well as make development of new supplies more difficult in some locations. The expanded challenge list also includes more restrictive policy within the institutional framework that controls water use. The historical view that abundant and low‐cost water supply had superior status relative to competing water uses has been replaced by one where efforts to expand water supply are viewed more critically. This development has resulted from a rise in environmental values and the associated changes in water management priorities. Sustaining adequate public water supply continues to be an important component of public policy, but the new and intensified challenges confronting water supply managers create a substantially altered environment for future decision making.

Select this Article		Urban Water Management: Innovations and Paradigm Shifts to Address 21^st Century Needs Robert Y. G. Andoh, Michael G. Faram, and Kwabena Osei ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)419 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Globally, the water and wastewater industry faces major challenges, both in developed and developing world regions. The developed world has enjoyed the benefits of the foresight of prior generations, with major strides gained in public health simply from innovations such as the humble sewer which has contributed more to human health than all developments in the medical field. Challenges faced in different regions are diverse in nature, magnitude and scale. Some are local in nature but others such as the impacts of Climate Change are truly global. The paper examines the status and evolution of innovations within urban water management (with particular reference to stormwater management) including impacts of regulation, barriers to innovation, current trends and paradigms. It is argued that there is a need to change the way we approach urban water management challenges, particular if the goal is to achieve more sustainable development in an increasingly urbanizing world.

back to top

SUSTAINABLE DESIGN TOOLS AND TECHNOLOGY

Select this Article		Go Green! Go Lansing! and Ultra‐Urban Bioretention Anne M. Thomas, Daniel P. Christian, Chad A. Gamble, and John T. Killips ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)420 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The City of Lansing has designed and constructed a streetscape along four blocks of Michigan Avenue, a downtown street leading to Michigan's Capitol, that includes bioretention to 1) beautify the corridor, 2) treat the “first flush” of street and sidewalk runoff, 3) educate the public, and 4) provide a pedestrian‐friendly environment. Design elements include placement of the bioretention cells, an analysis of the hydraulics, a retaining wall and footing design, an engineered soil specification, and plant and tree selection. The streetscape was designed in 2006 and constructed in 2007. The cost to construct the bioretention cell elements was approximately $1,000,000.

Select this Article		Balancing the Three Pillars of Sustainable Design for the Sugar Creek WWTP Expansion Project L. Kevin Mosteller, P.E. and Helene Hilger, Ph.D., P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)421 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Charlotte‐Mecklenburg Utilities (Utilities) in Charlotte, NC, is in the process of expanding its 20 million gallons per day (mgd) Sugar Creek Wastewater Treatment Plant (WWTP). The Sugar Creek WWTP, originally constructed in its existing configuration in 1929, was one of the first activated sludge plants in the United States. At that time, this rural location was several miles from the bustling center of town. Today, the plant is located in the heart of the urbanized south Charlotte community with a thriving business and shopping district and many large residential neighborhoods. As the area has grown, the plant has had to increase its rated capacity to 20 mgd through a series of expansion and upgrade projects. The existing Sugar Creek WWTP includes the following major liquid stream process components — influent flow equalization, primary clarification, an activated sludge process (aeration basins, blowers, and secondary clarifiers), effluent filtration, UV disinfection, and post aeration. Primary and waste activated sludge (WAS) biosolids from this facility are pumped to Utilities' McAlpine Creek WWMF for stabilization and disposal. Given the close proximity of the community to the facility, Utilities completed an extensive odor control project with participation from the surrounding community in 1999. For nearly 80 years, the Sugar Creek WWTP has served the City of Charlotte and has helped balance the region's significant economic growth with protection of water quality. In May 2007, a Wastewater Treatment Plant Expansion Study recommended various expansion and upgrade projects for Utilities, including a two‐phase expansion of the Sugar Creek WWTP from 20 mgd to 34 mgd (the Project). Phase I of this expansion effort is to be completed by 2012, with Phase II scheduled for completion by 2016. Charlotte‐Mecklenburg Utilities has set forth as a major goal of this Project the incorporation of sustainable design principles. The Project Team has developed many sustainable design opportunities that have been categorized under the three pillars of sustainable design — economic, social, and environmental.

Select this Article		Onsite Wastewater Treatment Using Evapotranspiration Bed System for the Wastewater from Sparsely Distributed Community Anna M. Doro-on and C. S. Rocky Shih ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)422 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The On-Site Sewage Facilities (OSSF), commonly named as Septic Tank Systems, is supposedly to provide adequate treatment for individual private dwellings. In reality, because of its poor efficiency and lack of sound engineering design, the OSSF has become a modern façade to pollute the land and groundwater resources legally and unethically. The objective of this paper is to present an innovative design approaches for OSSF based on evapotranspiration bed design formulations to provide the needed sustainability for land and local environment where the OSSF is situated.

Select this Article		A Water Quality Assessment of Two Green Roof Stormwater Treatment Systems M. P. Wanielista, M. ASCE, M. Hardin, and M. Kelly ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)423 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The use of green roofs in the United States for stormwater management purposes has become more popular in recent years. As a result there has been several research projects aimed at determining the volume control benefits of green roofs. While it has been speculated that green roofs also offer water quality benefits, little research has been done to quantify this claim. Within this paper, focus is placed on the water quality benefits of two specifically designed green roof stormwater treatment systems. They consist of an irrigated green roof with a cistern to store and reuse stormwater for irrigation. The primary water quality measures of concern are physical parameters, nutrients and bacteriological. These pollutants have been suspected of leaching out of the green roof growing media and from rainfall. Both of the green roofs use a select media for pollution control. This work quantifies the water quality benefits of green roof stormwater treatment systems and documents the effectiveness of specific stormwater designs.

back to top

SUSTAINABLE STORMWATER DESIGN APPROACHES

Select this Article		Environmentally Sound Approaches for Stormwater Management on Pacific Island Nations Patrick Kaspari, P.E., M. ASCE and Steven Allen, P.E., M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)424 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract This paper and presentation will focus on the unique stormwater management issues facing small Pacific Islands (e.g. highly erodible soils, severe precipitation events, dense and varied land use, public recreation in receiving waters, and sensitive benthic environments) and present environmentally sound and sustainable technologies to address these issues. The development of the Stormwater Management Plan (SWMP) for the Garapan drainage on the Island of Saipan, Commonwealth of Northern Mariana Islands (CNMI) is used as a case study for the paper, and we will present how the unique island culture and challenges lead to the development of Best Management Practices for this drainage that are environmentally sound, sustainable and effective.

Select this Article		Implementing Low Impact Design on Large Projects Scott E. Sonnenberg, P.E., M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)425 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Obtaining approval to use LID techniques in communities that have not seen or approved them is not always an easy task. The stormwater and zoning regulations may not be set up to grant approval without a lot of proof and discussion. Owners, municipal regulators and other consultants need to be convinced the systems are economical and can be maintained. This presentation will include some of the steps required to gain approval to use LID by the owner, the community, and the engineering review authorities, as well as the financial savings and opportunities of implementing LID. Two projects will be reviewed including a 45 acre suburban hospital site with 28 vegetated stormwater collection areas, 26 grassed detention basins, 5 wetland swales, and 5 extended wetland detention basins. The second site is a 119 acre suburban high school site which had to meet new state regulations limiting the annual infiltration volume for the developed site to the existing annual infiltration volume. This site includes the design of 22 parking island and other basin rain gardens, 3 water quality wetland basins to treat the first 1” of runoff, 9 wetland conveyance channels, 2 vegetated basins, and 1 extended wetland detention basin. The entire system daylighted over 3000 If of farm tiles and created over 8000 If of open channel and basin flow across the site.

Select this Article		Stormwater Capture, Reuse, and Treatment for Multipurpose Benefits Mark Madison, P.E. and Henriette Emond, Ph.D., P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)426 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Stormwater can be a blessing or a curse, depending on how it is handled. The conservation and reuse of stormwater can serve to enhance an environment that is lacking in water, even if only during certain times of year. Thus, stormwater that may cause flooding or overburden a collection system can be converted to an asset. The treatment of stormwater using a natural system rather than processing through a wastewater treatment plant can save valuable resources by increasing the capacity and prolonging the useful life of a treatment plant. The reuse of the stormwater before it ever reaches the treatment plant will similarly save resources and can provide additional benefits to water‐short end‐users. Stormwater can be accessed as a new source of water for municipalities and private enterprises. Innovative approaches to divert and treat or capture and distribute include constructed‐wetland stormwater treatment systems, small lot reuse, source reuse, stormwater capture, stormwater storage, and stormwater distribution. In most jurisdictions a water right is not required to use stormwater that is captured before it enters a natural stream or lake. Potential stormwater reclamation opportunities identified as part of an appraisal investigation conducted for the U.S. Bureau of Reclamation in the State of Hawaii are used to illustrate innovative approaches to converting stormwater to an asset. Example project concepts include stormwater interception and storage for addition to an existing irrigation distribution system on the Island of Hawaii, or installation of a deep infiltration trench to capture stormwater from urban development and introduce it into a brackish aquifer used for irrigation on Oahu. Similarly, a stormwater collection, treatment, and beneficial reuse system approach is illustrated by a Vancouver, Washington, project under development to treat industrial stormwater runoff in constructed wetlands for discharge to the Burnt Bridge Creek watershed. This provides an attractive alternative for industries and municipalities to reduce sewer collection and its associated costs and lost capacity. It also provides flow augmentation to the creek and restores watershed features.

back to top

NON‐POINT SOURCE POLLUTION: BMPS

Select this Article		Assessing the Effectiveness of Agricultural BMPs Using the Copula Approach Hemant Chowdhary, Z.‐Q. Deng, and Vijay P. Singh ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)427 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A variety of best management practices (BMPs), suitable for the abatement and control of non‐point source pollution have been developed and recommended for application in the state of Louisiana. Owing to comparatively poor water quality levels, the Mermentau and Vermilion‐Teche River basins in southwestern Louisiana have been prioritized for BMP implementation. Water bodies in these river basins have been found impaired to various degrees for their designated uses of fishing, swimming, and/or wildlife propagation. Evaluation of the improvement in water quality is essential in order to ascertain the effectiveness of these BMPs at the watershed scale. Consideration of inherent uncertainty is required while evaluating improvements in the water quality of various water bodies. Concentrations and loads of these pollutants show considerable dependence on flow characteristics. A better assessment of the variability of water quality can be based on the bivariate joint distribution of pollutant and flow variables. Conventional formulations for such joint distributions have certain restrictions with respect to the type of marginal distributions and the dependence structure. The new copula‐based approach overcomes such restrictions and allows modeling of joint behavior on the basis of marginals in their untransformed forms. This paper presents an evaluation of the effectiveness of BMPs that have been implemented in 11 watersheds of Mermentau and Vermilion‐Teche River basins. Statistical evaluation of improvements in turbidity and total suspended solids has been made for one of the watersheds on the basis of copula‐based conditional distribution concept for purposes of illustration. As concentration of these pollutants has significant dependence on flow magnitudes, the effect of flow is incorporated by employing these conditional distributions. The results are compared with those obtained using other conventional parametric and non‐parametric methods. The turbidity and total suspended solids levels are worst during spring months and this coincides with the sediment laden releases from the rice fields. Various hypothesis tests identify the watersheds for which the BMPs have been effective and also those for which improvements could not be established. Consideration of inherent uncertainties in various processes allows an objective assessment of the improvements that have been brought about by the implementation of various BMPs in Mermentau and Vermilion‐Teche River basins.

Select this Article		Bathymetric Survey and Acoustic Sediment Profiling of Fort Hood, Texas Sediment Retention Ponds and Cowhouse Reach; Belton Lake Dennis W. Hoffman, Thomas Gerik, and June E. Wolfe, III ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)428 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Erosion prevention and sediment retention are primary land management objectives for military land managers. Monitoring sediment retention structures and downstream water bodies for sediment deposition promotes effectively decision making and resource allocation. We utilized acoustic profiling coupled with Global Positioning System (GPS) technology to conduct detailed bathymetric surveys of Fort Hood training area sediment deposition within retention ponds and downstream waterbodies. Our objectives were: 1) determine the remaining sediment storage capacity of training area retention structures and 2) estimate exported sediment deposition within the Cowhouse Creek reach of Belton Lake. Bathymetric survey data were used to produce Geographic Information System (GIS) based spatial models for volumetric sediment analysis. We have determined the sediment retention capacity of Fort Hood's flood control structures have between 19% and 100% capacity remaining. The sediment distribution and thickness within a 136 HA segment of Belton Lake contains an estimated 1.1 million cubic meters of sediment was eroded from Fort Hood into this area of the lake.

Select this Article		BMP Pollutant Removal Efficiency Michael Horst, Robert Traver, and Erika Tokarz ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)429 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Stormwater Best Management Practices (BMPs) are receiving national acceptance as a viable means of controlling excess runoff due to rainfall events. BMPs allow for Stormwater to move directly to the localized groundwater table via infiltration and thereby return the post‐development outflow hydrograph peak‐flow and volume to pre‐development conditions. Another advantage to using BMPs instead of a traditional detention basin is thought to be the potential to remove non‐point source pollutants accumulated in the surrounding developed areas. Theoretically pollutants are carried into the BMP with the excess runoff and are allowed to infiltrate into the ground, thereby improving the quality of the surface water released by the BMP back into the environment. Additionally, pollutants also have the potential to be caught in the underlying soil layer and removed from the infiltrating water as it makes its way to the groundwater table. A water quality investigation was completed on three different types of BMPs; a bio‐infiltration pond, a Stormwater wetland, and a pervious concrete surface with underlying rock bed, in order to ascertain the pollutant removal efficiency of each of the various BMPs. The investigation involved a statistical analysis of the inflow water quality concentrations versus the outflow and infiltrating concentrations at varying depths beneath the ground surface. Constituents analyzed included: nitrogen, phosphorous, chloride, suspended solids, dissolved solids and Ph. The results of the analysis are mixed at each site with the Stormwater wetland having the greatest pollutant removal efficiency for surface water flows, and the bio‐infiltration pond having the greatest pollutant removal efficiency for infiltrating waters.

back to top

NON‐POINT SOURCE POLLUTION: CHARACTERIZATION

Select this Article		Factors Influencing Variations in Stormwater Runoff Quality from Single‐Family Residential Land Uses Roger H. Glick, P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)430 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Differences in stormwater quality are often associated with impervious cover and/or land use. However, two watersheds with similar impervious cover and land use may exhibit significantly different stormwater quality. This study examined the relationship between population demographics and stormwater quality in runoff from eleven single‐family residential land use watersheds in Austin, TX. Event mean concentration data for seventeen pollutants were standardized so all data could be combined resulting in one indicator value of water quality in the monitored watersheds. The data were then statistically compared demonstrating significant differences in water quality from watersheds with similar land use. A statistical relationship between population demographics (income, rental rate, education and population density) and the indicator variable was developed (r²=0.78). This relationship was then applied to single family areas in the Austin area creating a map of areas with potential water quality problems. This relationship may be useful in targeting areas for water quality programs including education and/or structural controls.

Select this Article		Nutrient Losses in Runoff from a New Golf Course Steve Starrett, Ph.D., P.E., Yunseng Su, Ph.D., P.E., Travis Heier, P.E., Jamie Klein, Jeff Holste, and Alok Bhandari, Ph.D., P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)431 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A new golf course community occupies a land area of approximately 1000 ac with 60% of its area in the Little Kitten Creek watershed. The watershed, previously grassland pasture, undertook a dramatic change in land‐use and watershed management since the golf course construction began in July 1998. A USGA‐funded research project started in 1996 enabled us to evaluate changes in surface‐water quality. Water quality data were divided into three sets: pre‐construction, during‐construction, and post‐construction. The mean concentrations of TN, TP, and sediment (TSS) in pre‐construction period were 1.18, 0.39, and 477 mg/L; during construction were 3.88, 0.93, and 2,754 mg/L; and during post‐construction were 2.10, 0.53, and 594 mg/L; respectively. Construction activities had the greatest adverse impacts on water quality. During the first 6 yrs of golf course operation, the TSS and nutrient concentrations returned nearly to the previous pasture values.

Select this Article		Quantifying Nitrate Flux during Storm Events J. S. Herman, A. L. Mills, G. M. Hornberger, A. C. Sofranko, and M. S. Olson ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)432 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Excess nitrate, mainly due to agricultural fertilizers, is a common problem in the surface water and groundwater of the Coastal Plain of the eastern United States. Baseflow conditions have been studied in an effort to understand nutrient loading to coastal waters, but there are many unanswered questions pertaining to nitrate flux during storm events. An automated stream sampler was deployed to collect water from a stream on the Eastern Shore of Virginia, USA, whenever stream stage rose following a rainfall event. Baseflow nitrate concentrations were typically 2.0–2.2 mg NO₃⁻‐N L⁻¹, and concentrations decreased rapidly with the onset of precipitation. Slightly in advance of peak discharge, the typical streamwater concentration was reduced to approximately 0.2–0.4 mg NO₃⁻‐N L⁻¹. Streamwater nitrate concentrations slowly returned to pre‐storm levels after the discharge level returned to baseflow. Even though the nitrate concentration of surface water decreased during storms, the average storm nitrate flux was approximately a factor of 3 times greater than the average base flow nitrate. Large quantities of nitrate were quickly transferred during storms due to the large volume of water with low nitrate concentrations flowing in the stream. Insights to nutrient management, particularly considering rates of biological uptake of nitrate, are supported by this more complete understanding of the dynamic flux of streamwater nitrate to coastal waters.

Select this Article		The Atmosphere as a Source of Water‐Soluble Volatile Organic Compounds Found in Urban Streams Scott J. Kenner and David A. Bender ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)433 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Volatile organic compounds (VOCs) are frequently detected in surface waters of the United States. To reduce their occurrence in urban streams, it is imperative to understand the sources of these pollutants. The atmosphere is a potential source of selected water‐soluble VOCs in urban streams and was investigated in this study. Air and surface‐water VOC data collected during 1996 to 2002 from 10 monitoring sites from the U.S. Geological Survey's National Water‐Quality Assessment (NAWQA) Program were examined. These sites were selected to evaluate the potential for direct transport of VOCs from the atmosphere to urban streams. Concurrent samples (air and surface water) were collected from eight sites, but two sites had available data that were compared based on the closest sampling dates. Analytical results of 87 VOCs were screened by evaluating the occurrence and concentrations in both air and surface water using defined categories, and equilibrium concentrations in surface water (C_w^s) were calculated based on the measured air concentrations. Four VOCs (acetone, methyl tert‐butyl ether (MTBE), m‐ and p‐xylene, and toluene) were in the category of detected in more than 20 percent of surface‐water samples and in more than 10 percent of air samples, with at least 10 percent of C_w^s concentrations greater than the aqueous long‐term method detection level (LTMDL). One VOC, benzene, was in the category of detected in more than 20 percent of surface‐water samples and in more than 10 percent of air samples, with at least 2 percent of the C_w^s concentrations greater than one‐half the aqueous LTMDL. Six VOCs (chloroform, methylene chloride, perchloroethene, p‐isopropyltoluene, 1,1,1‐trichloroethane, and trichloroethene) were in the category of detected in more than 20 percent of surface‐water samples and in more than 10 percent of air samples, with less than 1 percent of C_w^s concentrations greater than one‐half the aqueous LTMDL. Five VOCs were identified as having the atmosphere as a possible source of contamination to small urban streams: acetone, benzene, MTBE, m‐ and p‐xylene, and toluene. Of these five VOCs, acetone, benzene, and MTBE were consistently in equilibrium with the atmosphere. Depending on the site and season, the atmosphere can serve as a probable dominant source for VOC contamination in urban streams.

back to top

NON‐POINT SOURCE POLLUTION: MODELING

Select this Article		Coupling of Atmospheric Deposition, Surface Runoff and River Transport Models for Drinking Water Protection and Homeland Security David E. Amstutz, Ph.D., Rakesh Bahadur, Ph.D., Michael C. Monteith, Mondher Chehata, Ph.D., and William B. Samuels, Ph.D. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)434 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Surface runoff of contaminants has been included as a source term in the Incident Command Tool for Drinking Water Protection (ICWater). This allows for modeling of chemical/biological/radiological contamination resulting from atmospheric deposition or direct application to the watershed. ICWater is a network‐based toxic spill model that calculates time‐of‐travel and concentration of contaminants based on real‐time stream flow data. The work described in this paper couples ICWater with: (1) a methodology for determining surface runoff of contaminants and (2) the Hazard Prediction and Assessment Capability (HPAC) model which calculates atmospheric deposition. The coupled models are operationally functional for all of the U.S. The Geospatial Stream Flow Model (GeoSFM) is being coupled with HPAC for application to areas outside the U.S. where ICWater does not apply.

Select this Article		Modeling Canopy Emission for Improving Pesticide Runoff Loss Simulation Bing Chen ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)435 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract This study developed a dynamic two‐big‐leaf multilayer pesticide emission model (PeCM) to simulate pesticide loss to the atmosphere from crop canopy. The pesticide volatilization, leaf residue and washoff, as well as rainfall interception, evaporation and transpiration, were considered in the model to help simulate the whole process of pesticide canopy emission. The PeCM was further incorporated into a pesticide runoff loss model (PeLM), which was previously developed by the author to simulate pesticide loss through surface runoff and soil erosion. To verify the feasibility of the developed model, a case study was conducted in the Auglaize‐Blanchard Watershed in Ohio. The results demonstrated that the PeCM was able to simulate pesticide emission to the atmosphere. Furthermore, to investigate the performance of the modified PeLM, the modeling outputs were compared with the observed data as well as the outputs of the PeLM. The results indicated that the modified PeLM had advantages in accounting for more pesticide transport processes and improving the simulation accuracy.

Select this Article		Modeling the Transport, Transformation and Fate of Distributed Contaminants across the Land Surface Zhonglong Zhang and Billy E. Johnson ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)436 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract CTT&F was developed as a physically‐based, spatially distributed watershed contaminant transport, transformation and fate sub‐model for existing hydrological modeling systems. To better predict the ultimate fate of contaminants through the various landscape media, physical transport and transformation processes in CTT&F are simulated for each cell and routed to the watershed outlet. This permits the contamination mass and concentration at any cell in the watershed to be examined. For uplands, CTT&F simulates contaminant erosion and the 2D transport process of the eroded material. For channels the sub‐model simulates the erosion of bed contaminants and the 1D downstream transport of this material together with washload supplied by the overland flow. The CTT&F sub‐model in conjunction with distributed hydrologic transport models may be used to simulate solid contaminant and partitioning among truly dissolved phase, dissolved organic carbon (DOC) bound phase and sediment (multiple grain sizes) sorbed phase of the contaminant. In this study, CTT&F was coupled with a distributed hydrologic model to simulate RDX and TNT using an experimental test plot. Compared with measured data from the plot experiment, the results show that the model simulations agree well with the measured data set.

Select this Article		The Estimation of Total Nitrogen and Total Phosphorus Outflow Loads from Watersheds Located behind the Closed Water Area Hiroshi Takimoto, Kazuo Murashima, Iwao Hashimoto, and Toshisuke Maruyama ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)437 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract In this study, the amounts of the outflow loads of nitrogen and phosphorus from the Kahoku‐gata lake at Ishikawa Prefecture in Japan is estimated, and measures for the load reduction are examined. The composite reservoir model is used to estimate the runoff discharge from watersheds. This model consists of four kinds of tank models to suit the different land use categories; forest, paddy field, farmland and city. The simulation results show the good fitting of the curve representing between observed and calculated discharges. The amounts of the outflow loads of T‐N and T‐P are estimated by using two methods (the pollutant load factor method and the LQ equation method). Based upon the loading estimates from 1998 to 2002, Kahoku‐gata lake received approximately 661 t/yr of T‐N and 31 t/yr of T‐P. It is clear that the largest contributor of loads was from paddy fields. The reduction measures for effluent loads will focus on influence of reuse of irrigation water and fertilization of the slowly available fertilizers. As a result, each measure could reduce about 10% of effluent loads. It was judged that the strategy combing these measures was effective for controlling the effluent loads.

back to top

TMDLS

Select this Article		Bacterial Total Maximum Daily Load Analysis for Copano Bay Stephanie L. Johnson, David R. Maidment, and Mary Jo Kirisits ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)438 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract With over 300 bacterial total maximum daily load (TMDL) studies to be completed in the State of Texas, the Texas Commission on Environmental Quality (TCEQ) is looking for rapid, non‐controversial modeling approaches. Of particular interest is the development of a “simple” modeling approach for coastal systems where many of the TMDL studies are required. The focus of our work is to develop a new bacterial TMDL modeling approach for the Texas Gulf Coast by combining previously approved models with nationally available datasets. This paper discusses the methods used to calculate bacterial loadings from the Copano Bay watershed to Copano Bay. It also explores how the tidal prism method will be modified for application to Copano Bay and its tidal river segments.

Select this Article		The Cedar River Basin Pathogen Total Maximum Daily Load — A Case Study for Watershed‐Scale Total Maximum Daily Loads Jason T. Love and Teresa P. Whitney ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)439 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A recent analysis of the Total Maximum Daily Load (TMDL) program by the Environmental Protection Agency (EPA) concluded that states are confronted with a significant increase in the number of TMDLs that need to be developed in the next decade. The majority of these TMDLS will be more complex than those developed to date and the level of resources and funding are not anticipated to increase. To exacerbate the problem, many states are behind the curve and others have to comply with Consent Decrees that establish an accelerated pace of TMDL completion. EPA concluded that one strategy to address the maximum number of impairments in the most expeditious and cost‐effective manner was developing TMDLs using a holistic approach on hydrologically connected impaired segments; i.e., a watershed‐scale approach to TMDL development and implementation. This paper presents a case study of the watershed approach applied to Cedar River Basin located in Iowa. The watershed is approximately 8,000 square miles in size, has nine waterbodies impaired for bacteria, and is under a Consent Decree that requires an aggressive schedule for TMDL development. The source allocation was complicated by the fact that there are 11 Municipal Separate Storm Sewer Systems (MS4s) within the watershed, over 100 National Pollutant Discharge Elimination System (NPDES) facilities, and over 80 percent of the watershed is used for raising crops and a large population of livestock. This paper will present a framework that was developed to perform the allocation analysis and estimate the impact reductions to loads from these stressors had on in‐stream concentrations throughout the watershed. The framework uses the Bacterial Indicator Tool (BIT), Hydrologic Simulation Program‐Fortran (HSPF), the Load Duration Curve (LDC) model, and MATLAB to analyze the data and perform postprocessing on model results. The framework ensures that water‐quality impacts from source reductions upstream to downstream adequately account for the impacts of pollutant fate and transport mechanisms. This ensures the TMDLs and implementation plans within the watershed are linked.

Select this Article		Comparisons of Methods to Calculate TMDLs for E. coli: Load Duration Curves, Mass Balance, and HSPF Tina Petersen, Ph.D., Camille W. Sowells, P.E., Hanadi S. Rifai, Ph.D., P.E., and Ron Stein, Ph.D. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)440 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Total maximum daily load (TMDL) studies determine the maximum amount of a pollutant that a body of water can assimilate while still meeting water quality standards. TMDL studies generally follow a standard procedure—identification of sources, data gathering and monitoring if needed, and use of a water quality model to determine the TMDL. This paper presents findings of a study being conducted on Buffalo Bayou, an urban bayou in Houston, Texas. Identified potential sources of bacteria include point sources — such as wastewater effluent discharges, sanitary sewer overflows, and dry/wet weather municipal storm sewer system (MS4) discharges — and nonpoint sources such as, wildlife, stream sediment, and failing septic tanks. This study has developed three separate methods of identifying TMDL end points: load duration curves (LDCs), a mass balance method using a tool called Bacteria Loading Estimator Spreadsheet Tool (BLEST), and a spatially and temporally variable Hydrologic Simulation Program — Fortran (HSPF) model.

Select this Article		Pathogen TMDL Development in Karst Watersheds: Challenges and Solutions V. Chandramouli, P.E., Ph.D. and L. Ormsbee, P.E., Ph.D., M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)441 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Watershed simulation models are popularly used for developing Total Maximum Daily Loads (TMDL) for different water quality parameters. The TMDL modeling process typically involves four stages: hydrologic calibration, water quality calibration, TMDL development, and load reduction analysis. The success of the whole process initially depends on successful hydrology calibration. This paper presents the results of an iterative methodology that was developed for use in calibrating HSPF for a karst watershed. This study focused on the development of a pathogen TMDL for Cane Run Watershed in central Kentucky. The headwaters of the watershed originate within the urban services boundary of Lexington, Kentucky and then flow through a predominately rural area which contains several horse farms. Due to the area's karst topography, this basin contains several large sink holes that divert flow from the part of the upper watershed to an adjacent watershed where it emerges at Royal Spring which serves as a primary water supply for the adjacent city of Georgetown Kentucky. As a consequence, the streamflow in much of the upper part of the watershed is essentially zero for many months of the year. This phenomenon presented several challenges in trying to characterize the watershed loadings as well as how to model the system so as to develop an effective TMDL.

back to top

TMDLS: IMPLEMENTATION

Select this Article		Hawaii Department of Transportation's Approach in Meeting TMDL: A Comprehensive Implementation Strategy Chin Y. Lien, P.E., Robert E. Bourke, Robert Shin, P.E., and Larissa Sato, P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)442 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Among the many impaired waterbodies on the Island of Oahu that have been listed in the 303(d) of Clean Water Act, three waterbodies, Kawa Stream, Ala Wai Canal, and Waimanalo Stream have EPA approved Total Maximum Daily Loads (TMDL) established by Hawaii Department of Health (HDOH). Load allocations were developed for all three waterbodies as part of the process. Two watersheds, Kawa and Ala Wai Canal, have waste load allocations (WLA) assigned to several NPDES MS4 permit holders including the Hawaii Department of Transportation, Highways Division (HDOT‐Hwys). HDOT‐Hwys has developed a comprehensive strategy that includes the implementation and monitoring plan for the three watersheds. The TMDL/WLA Implementation Plan identifies specific activities where the reduction of total nitrogen and total phosphorus discharges in each watershed are necessary to comply with the WLAs. The monitoring plan specifies the water quality monitoring and tracking activity necessary to demonstrate efforts to comply with the urban source WLAs assigned to HDOT‐Hwys and the effectiveness of the BMPs and the WLA implementation.

Select this Article		“Is Your Representative Outfall Really Representative?” Factors that Can Affect Representative Discharge Sampling Data Camille W. Sowells, P.E., Christina Petersen, Ph.D., Carolyn White, and Catherine Elliott ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)443 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract In 1987 Congress amended the Clean Water Act requiring EPA to establish NPDES requirements for storm water discharges. As part of the NPDES permit requirements for Phase I municipal separate storm sewer systems (MS4), the operator of the system is required to perform field screening analysis of the major outfalls to detect illicit connections. The operator is allowed to designate “representative outfalls” to characterize discharges from drainage areas of similar land‐uses. Volume‐weighted water quality samples are collected at the representative outfalls during storm events and used to calculate event mean concentrations (EMCs). Data from this characterization may be used in a number of applications including: identification of illicit discharges, determination of load allocations on impaired stream segments in a TMDL process, selection of best management practices to reduce or eliminate pollutant discharge, and prioritization of infrastructure improvements. Each of these applications could result in significant resources to execute. Therefore, it is important to collect data from the representative discharges, which are accurate, and correctly characterize the drainage areas they represent. This paper presents a case study evaluation for one of Harris County Flood Control District representative outfall located in Houston, Texas. Houston has over 15 bayous that drain the relatively flat, coastal watershed. Houston receives 50‐inches of rainfall on average, evenly distributed over the year. In addition, the region frequently experiences short‐duration, high‐intensity rainfall events that can cause brief flooding. There are four representative outfall land uses are used to characterize Harris County, Texas: single family residential, multi‐family residential, commercial, and industrial. These designations do not fully represent the land uses in the County. A number of land use activities are not accounted for in these designations (i.e. transportation, recreational, institutional, and undeveloped areas.) This study is focused on identifying factors that may influence results collected during storm water sampling at representative outfalls. During this study, a procedure was developed to investigate the current status of a representative monitoring site. First, the drainage area of the representative outfall is delineated. This drainage area is used to identify land use and potential sources of pollution. Finally, identified sources were field verified, and GPS locations collected for each potential source.

Select this Article		Kaelepulu Pond: Community Efforts to Preserve an Urban Tropical Estuary Robert E. Bourke ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)444 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Kaelepulu Pond is the 90‐acre estuary remnant of a 200–400 acre ancient Hawaiian fishpond in the community of Enchanted Lake on the windward shore of Oahu, Hawaii. The Pond is central to the highly urbanized watershed and connected via a series of drainage canals which terminate to the ocean across a popular tourist beach. The City of Honolulu has 73 NPDES permitted storm drains entering the pond and canal estuary system. During the past two decades, the community has noted significant shoaling near large storm drain inlets, overgrowth by non‐native mangrove, loss of oyster beds, increased fish die‐offs, periods of noxious odors, and a continuous deterioration in the ecological quality of the pond. A series of community initiated investigations of bathymetry, pond water quality, and storm water input coupled with a Hawaii Department of Health funded mangrove removal project has combined to yield a greater understanding of the problem and the beginnings of restoration activities.

Select this Article		Modeling a Basin‐Wide Extrapolation of Stormwater Management Activities: A Case Study of the Lake Tahoe Clarity TMDL Implementation Plan for Developed Areas John Riverson, Brent Wolfe, Ed Wallace, and Leslie Shoemaker ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)445 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Lake Tahoe is a designated Outstanding National Resource Waterbody. However, lake clarity has dropped at a rate of 9 inches per year since the late 1960s, with ultra‐fine sediment and nutrient driven algae production as the primary stressors. About 70% of the total fine sediment particles are estimated to come from developed areas, which make up 10% of this largely rural watershed. With more than $1.5 billion estimated as the cost to restore lake clarity, a premium has been placed on developing informative decision support analyses. A detailed watershed model was developed to represent the unique orography and hydrology of the Lake Tahoe Basin, predict loads by land use source, and calculate TMDLs allocations. This paper highlights a methodology that informs the watershed model regarding pollutant load reductions achieved from implementation of Best Management Practices (BMPs) under different physiographical settings for developed land in the Lake Tahoe Basin.

Select this Article		Water Quality Data for Lake Nutrient TMDLs: How Much Is Enough? Rebecca Kluckhohn ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)446 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract In the land of 10,000 lakes, setting lake nutrient Total Maximum Daily Loads (TMDLs) is a big job. Over 300 nutrient impairments have been identified with only 10–20% of Minnesota's lakes assessed. Current approaches to setting lake nutrient TMDL's involve expensive data collection modeling efforts. This paper compares implementation plans developed for lakes using large and small data sets and asks the question: How different is a $5,000 Implementation Plan from $50,000 plan? Due to pressure from lakeshore residents concerned over rapidly declining water quality in Cedar Lake, we used an Implementation Strategy Ranking System (ISRS) in conjunction with a small but robust set of data and tools to draft an implementation plan for the lake. The ISRS was used to understand the relative costs and uncertainty associated with each implementation strategy. Additional data was collected to reduce the uncertainty and refine the implementation plan; however the differences between the draft and final plans resulted mostly from stakeholder input and logistical limitations, not from a reduction in uncertainties afforded by the additional data. Lessons learned can be used in implementing lake nutrient TMDLs for less.

back to top

TMDLS: MODELING

Select this Article		Development of a Hydrodynamic and Water Quality Model for the Dominguez Channel Estuary Ying Poon, P.E., David Cannon, P.E., Sherilyn Kimura, P.E., Andrew Jirik, and Paul Johansen ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)447 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The Dominguez Channel Estuary is part of a complex circulation system that includes the Los Angeles/Long Beach Harbors (Harbor) within San Pedro Bay, California. As part of the TMDL development process, this study was conducted to develop a three‐dimensional hydrodynamic and water quality model (DCEM) that can accurately predict pollutant transport through the Dominguez Channel Estuary and into the Harbor. A field program was implemented to collect sufficient data to calibrate and verify the DCEM for water levels, velocity, salinity, dye, TSS, chromium, copper, lead, and zinc under dry and wet weather conditions. An iterative, layered approach was developed to calibrate the DCEM that involved evaluating the model grid design and the selection of initial conditions, boundary conditions, transport model parameters, and water quality model parameters.

Select this Article		Modeling the Impact of Complex Irrigation, Agricultural Impoundments, and Mining Activities on Salinity and SAR in the Tongue River Watershed, Montana Ron Steg, Jason Gildea, John Riverson, Jon Butcher, and Kevin Kratt ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)448 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The Tongue River watershed extends through two states and exhibits highly variable topography and climate patterns. While the Big Horn Mountains represent 9 percent of the total watershed area, they contribute roughly 63 percent of all the water in the Tongue River system through snowmelt. Other unique watershed features include high‐altitude reservoirs and diversions, extensive irrigation for agriculture, coal bed methane operations, and stock ponds. Tetra Tech developed a comprehensive model of the watershed based upon locally available datasets and innovative process‐based model customizations using the Loading Simulation Program in C++ (LSPC) modeling platform. The focus of the model was to simulate hydrology, salinity, and sodium adsorption ratio (SAR). This paper highlights the challenges, solutions, methods, and results associated with this complex modeling application.

Select this Article		Simple Tools for Water Quality Modeling and TMDL Development Tatiana X. Hernandez, P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)449 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Water quality models are being used to determine pollutant loads to water bodies and for developing Total Maximum Daily Loads (TMDLs). Watershed, stream, and reservoir water quality models include a wide range of models that can be applied to virtually every water body type (including estuaries, bays, lakes, bayous, reservoirs, major rivers, streams, and ponds), pollutant type (from nutrients, dissolved oxygen [DO], and bacteria to PCBs, metals, pH, and pesticides) and source type (including urban, agricultural, mining, and forestry). Modeling selection and criteria are based on the water body type and behavior, pollutants and processes of concern, source types, and other defining factors identified during the characterization of the watershed. The vast majority of these models are complex and require a significant amount of input data and time. When modeling water bodies with limited data, simple modeling tools such as load duration curves, BATHTUB, and QUAL2K are more effective. Load duration curves are a simple and accurate method of determining existing and allowable pollutant loads in streams. Because the approach establishes loads based on a representative flow regime, it inherently considers seasonal variations and critical conditions attributed to flow regimes. BATHTUB is a steady state model that predicts eutrophication response in lakes and is commonly used for simulating nutrient loads. QUAL2K is a one‐dimensional steady state river and stream water quality model widely used for simulating dissolved oxygen and pH. Load duration curves, BATHTUB, and QUAL2K are water quality models that are efficient and simple to use, and provide adequate results in simulating pollutant loads, loading capacity of water bodies and pollutant load reductions required to meet water quality standards.

Select this Article		TMDL Watershed Analysis with the Physics‐Based Hydrologic, Sediment Transport, and Contaminant Transport Model GSSHA Fred L. Ogden, Ph.D., P.E., M. ASCE, Aaron R. Byrd, A. M. ASCE, Charles W. Downer, Ph.D., P.E., M. ASCE, and Billy E. Johnson, Ph.D., P.E., M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)450 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The Gridded Surface/Subsurface Hydrologic Analysis (GSSHA) model has been developed with research funding from the US Army, the US Environmental Protection Agency (EPA), US Army Corps of Engineer (USACE) civil research programs (LMS and SWWRP), and with funding for civil and military applications to fill an existing need; GSSHA has the ability to explicitly simulate spatially‐varied hydrologic processes to solve a variety of common engineering problems. The GSSHA model features two‐dimensional overland flow, sediment and water quality transport, coupled to one‐dimensional stream flow, sediment and water quality transport, integrated with two‐dimensional groundwater flow. GSSHA simulation times can be minimized by running GSSHA on parallel architectures, such as 64‐bit multi‐processor PCs, or any shared memory resource. Model setup and post‐processing are greatly aided by the DoD Watershed Modeling System (WMS). Recent additions/improvements to the GSSHA model include: subsurface pipe networks for urban and agricultural drainage, improved sediment erosion and transport, simulation of wetlands, lakes, and reservoirs, and coupling of GSSHA to the Nutrient Sub‐Module (NSM) to allow complex interaction among nitrogen and phosphorous species, with the intent to add more contaminants as modules are developed. GSSHA has been used for analysis and prediction of a wide range of issues and measures including: surface water runoff, soil moisture, groundwater recharge, transport of sediments and associated contaminants, transport of volatile contaminants, management of military training lands, and effects of urbanization on runoff and sediment loading. This paper focuses on improvements of the GSSHA erosion source and sediment transport routines.

Select this Article		WinHSPF Model Simulations of Nitrogen and pH for a Low‐Alkalinity Stream Impacted from Atmospheric Acid Deposition M. Cai and J. S. Schwartz ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)451 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The Hydrologic Simulation Program‐Fortran (WinHSPF) was used to simulate the stream flow, ammonium, nitrate and pH for the No land Divide watershed from 1999 to mid‐2006, to evaluate the model applicability to watersheds impacted by acidic deposition. Noland Divide watershed is located in the Great Smoky Mountains National Park, Tennessee. Model calibration for hydrology was satisfactory showing total error of 2.1% for stream discharge during simulation period. The model simulated low ammonium concentration (0.04 mgN L⁻¹) in the stream, which is likely due to the high nitrification rate on the land converting most deposited ammonium to nitrate. The deviation between the simulated and measured nitrate concentration was 0.03 mgN L⁻¹ while the mean observed nitrate concentration was 0.57 mgN L⁻¹. Although the model output for pH (from 5.7 to 6.0) were similar to observed stream pH measurements (from 5.5 to 6.5), model calculations of pH did not consider stream acidification due to mineral anion acids. The WinHSPF model computes pH simply based on carbonate system and alkalinity equilibrium, and therefore is only applicable to waterbodies governed by the carbonate‐dominated chemistry. In low alkalinity waters like those found in the Noland Divide watershed, WinHSPF can not predict stream chemistry response from impacts of acidic deposition.

back to top

COASTAL PROCESSES MODELING I

Select this Article		Current and Sediment Numerical Model Applied in the Project of Campha Thermal Power Plant Bai Yuchuan, Tian Qi, and Yan Xigen ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)452 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The Thermal Power Plant is located in Cam Pha town, Quang Ninh province which is in Vietnam northern alongshore, the plant capacity is up to 2×300MW. The recirculated cooling water is designed to intake the seawater direct current waterworks, in which the nearby seawater is used as the source of cooling water. Topographic condition, Geology, wind, wave, Sediment distribution are analyzed. The two‐dimensional current and sediment numerical model are adopted. According to different intaking and draining design proposals, sediment movement and seabed evolution process in sea area should be simulated under the action of wave and tide current. The results show that the power station that lay in HongJi‐GaiBaoDao sea area belong to the balance region between erosion and deposition, the weak erosion evolution occur after constructing the power station. Under the association action of field measurement tide stencils and characteristic wave, the recommended scheme can satisfy with the intaking water requirement. In view of the action of sinking water, the both side of open channel entrance appear small scale erosion channel, which is good for intaking water. The both side levee toe of open channel and the foreland of intaking water channel exist some scale erosion region, the protective facility need to adopt such as jackstone protective facility.

Select this Article		Multiple Time Scales and Coupled Mathematical Modeling of Turbidity Currents Peng Hu and Zhixian Cao ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)453 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Turbidity currents can entrain sediment from the bottom boundary, resulting in active sediment transport and rapid bed deformation, which in turn affects the evolution of turbidity currents. Yet previous mathematical models of turbidity currents are mostly based on mild bed deformation and weak sediment transport, in which the feedback impacts of sediment transport and bed deformation have been ignored to a certain extent. It so far remains unknown if this could have considerable effects on the evolution of turbidity currents. This paper extends the recent analysis of multiple time scales of subaerial sediment‐laden flows to subaqueous turbidity currents. The relative time scale of bed deformation is demonstrated to delimit the applicability region of layer‐averaged models for turbidity currents. Self‐accelerating turbidity currents are revisited to substantiate the significance of fully coupled modeling for turbidity currents featuring active sediment transport and rapid bed deformation.

Select this Article		Recent Developments in Modeling Coastal and Estuarine Morphological Processes and Applications to Coastal Flood Management and Erosion Protection Yan Ding and Sam S. Y. Wang ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)454 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract This paper presents a brief review of recent developments of integrated coastal/estuarine models for simulations of coastal and estuarine morphological processes and applications to coastal flood management and erosion protection. It emphasizes the advancement of the integrated coastal models to simulate coupled coastal hydrodynamic and morphodynamic processes by taking into account the combined effects of astronomical tides, waves, winds, river flows, and their complicated interactions with beach erosion, sediment transport and morphological changes in coastal and estuarine waters. It also gives an engineering application example case done by the NCCHE's models for simulating flood and morphodynamic processes in an estuary which were driven by a hypothetical event due to hazardous storm and flood with a100‐year return period.

Select this Article		Strategies for Enhancing the Predictive Ability of Sediment Transport Models R. Mayerle and C. A. Escobar ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)455 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract In this paper the relevance of several factors affecting the predictive ability of sediment transport models are identified and strategies for its improvement are proposed. The investigations have been carried out in a tidally dominated coastal area on the German North Sea. The strategies and functional relationships proposed here might be applicable to similar coastal areas. Emphasis is given to the integration of field measurements and process‐based models to deliver better descriptions of the input parameters over the entire study area. The inclusion of cohesive properties of sediments, spatial variability of bed roughness and sediment grain sizes as well as the incorporation of the conditions below the loose sediment layer proved to be most relevant factors. As a result of the various enhancements and excellent agreement between computed and observed values resulted.

back to top

COASTAL PROCESSES MODELING II

Select this Article		Application of 2‐D Mathematical Tidal Currents and Sediment Model in Sheyang Estuary Regulation Project Yunfeng Xia, Yuncheng Wen, Qinan Ma, and Rui Song ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)456 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract In this paper, the hydrologic features including tidal currents, wave, sediment and seabed topography in the project sea area are analyzed. The relationship of the sediment concentration and the tidal currents is established. A 2‐D tidal currents and sediment mathematical model with the wave radiation stresses and non‐equilibrium sediment transport is applied to calculate the hydrodynamic force and the field sediment concentration change caused by the regulation engineering project in the Sheyang Estuary. It is necessary to analyze the river mouth regulation construction and the navigation to be dredged to the Sheyang estuary flood influence, as well as to study the sedimentation problem for deepening the navigation channel in the Sheyang estuary.

Select this Article		Numerical Simulation of 2‐D Model of Cooling Water Draining into the Bay with Waves and Tidal Currents Fang Yang, Lin Wang, You‐wei Li, and Yong He ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)457 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract With the development of economy in coastal zones in China, the energy requirement is increasing greatly. Many large power plants have been built near bays in China recently, and function of power plant need drain large warm water into bays, which will change current field near outfall and have effect on seawater temperature going up in the bay. In this study, the combined actions of waves and tidal currents in estuarine and coastal areas are considered and a 2‐d hydrodynamics and temperature transport model by waves and tidal currents has been established, in which. The wind action and the effect of radiation stress of waves on current and temperature transport are taken into account. It can simulate the distribution condition in current field and temperature field of cooling water correctly and provide credible technical data for ocean environmental impact assessment.

Select this Article		Numerical Simulation of Aquatic Eco‐Environment for Coastal Water of Bohai Bay Jianhua Tao and Di Mu ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)458 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Due to the rapid economic development along the coastal area of Bohai Bay, serious contamination and deterioration of the eco‐environment has been manifested as a result of intensified exploitation activities. In this paper, the hydrodynamic characteristics of the water exchange and long‐shore currents of Bohai Bay have been analyzed by numerical simulation. Field monitoring and Grey Relation Valuation Method were adopted to study the current situation of the aquatic system. The results implied a strong influence of land‐source pollution. To determine the nutrient contribution of the bottom sediment to the water layer and to provide source data for the simulation of the dynamic of plankton ecology system, nutrient exchange fluxes between the water and bottom sediment interface was studied, which indicated the strong influence of the nutrient release from bottom sediment. The characteristics of the dynamics of the eco‐system of Bohai Bay were simulated by using a 2D eco‐hydrodynamic model, which consisting of a hydrodynamic sub‐model and an eco‐system sub‐model. The results agreed with the measured data. By using numerical simulation, the impacts of coastal exploitation on the hydrodynamic and eco‐dynamic processes in Bohai bay have been analyzed. The further development of numerical simulation of aquatic eco‐environment for coastal water has been introduced.

back to top

COMPUTATIONAL MODELING OF FLOOD FLOW

Select this Article		2‐D Flood Modeling of Multiple Simultaneous Dam Failures Jeff Jorgeson, Woodman W. Berry, Mark R. Jourdan, and Xinya Ying ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)459 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Two‐dimensional modeling of dam failure flooding has been successfully demonstrated through the use of such models as the CCHE2D‐Dambreak model. This modeling approach offers a tremendous improvement over traditional one‐dimensional solutions in terms of the high degree of spatial and temporal detail in the model results. Detailed output for water depth, flow velocity, timing of flood arrival and duration of flooding is available from the two‐dimensional model such that all aspects of the flood may be thoroughly analyzed. A special case in flood modeling from dam failure involves simulation of the flooding that may result in the event that more than one dam fails and the floodwaters from the multiple dams combine into a single flood event. This may occur when two or more dams are located in tandem along the same river, or it may occur when two or more dams are located on separate tributaries that flow into the same river. Failure of a single dam is a rare event, and multiple simultaneous dam failures are certainly even' rarer. However, the ability to model such an event and understand the potential flood conditions that may occur under various scenarios involving the timing of each dam failure and the water levels in each dam is important. The CCHE2D‐Dambreak model offers such a capability, and this paper presents an application of that multiple dam failure modeling feature. An example is presented in which two dams located in tandem on the same river fail, and several scenarios are modeled to investigate the combined flood event.

Select this Article		Influence of the Wen River Floods on the Effectiveness of Water and Sediment Regulation in Eroding the Shandong Reach of the Lower Yellow River Jiang Enhui, Liu Lifei, Dong Qihua, and Li Junhua ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)460 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The Wen River is the only branch after the Yellow River entering Shandong province. Because of good vegetation and little sediment content, the Wen River is a typical clear river in the Yellow River basin. After six water and sediment regulations by the end of 2006, erosion of the entire lower Yellow River from Henan to the estuary was realized as expected. One of the most important findings is that it is successful in preventing the flushing of the Henan reach channel and the silting of the Shandong reach channel at the same time, which people worried most. But we noticed that from 2004 to 2006, during the periods of water and sediment regulations, the Yellow River has received from the Wen River certain order of magnitude floods each year. We used a mathematical model for the Lower Yellow River to study the effect of adding the flow from the Wen River on the effectiveness of water and sediment regulation in eroding the Shandong Yellow River. It is found that the adding of the floods from the Wen River benefit the eosion of the lower Yellow River in the Shandong Province.

Select this Article		Integrated Modeling for Inundation Flows in Urban Areas Yoshihisa Kawahara and Tatsuhiko Uchida ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)461 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract This study proposes an integrated physically based distributed model for inundation flows. It has four sub‐models: a hydrological model for rainfall‐runoff, a two dimensional shallow water model for overland flows, a one dimensional model for flows in sewer networks, and a data management model. The 2‐D shallow water model is at first tested against the physical experiments about the inundation due to levee breach. Then the model is applied to the inundation caused by the extreme tidal surge in Takamatsu city, a local capital in Japan in 2004. Comparisons with measured data show that the model reasonably describes the inundation process in the urban area and that the sewer network played an important role in draining the sea water.

Select this Article		Modeling Urban Flood Inundation in a Parallel Computing Environment Nigel Wright, M. ASCE and Ignacio Villanueva ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)462 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Algorithms for parallel processing have been described and demonstrated for grids containing over six million cells. This has been achieved by the use of the freely available MPI libraries. The efficiencies are good and demonstrate that such a technique can be used in urban areas without loss of representation of physical phenomena. The implementation was successful for both a large cluster and a smaller dual‐core PC system. Further studies will be carried out to analysis the parallel efficiency. Work is also underway to implement a multi‐block approach that maintains the Cartesian grids used here, but that allows for different resolutions to be used in different sub‐domains as appropriate. Further simulations for Carlisle at a resolution of 1m will be carried out with a DEM that better represents the main channel.

back to top

MODEL APPLICATIONS IN HYDRAULIC ENGINEERING

Select this Article		Free Surface Simulations for a Removable Spillway Weir Xiaoli Fu, Marcela S. Politano, and Larry Weber ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)463 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The flow field around a removable spillway weir structure (RSW) at Little Goose Dam is numerically predicted. The modeling approach and main characteristic of the CFD model used in this study are presented. The model is based on the Reynolds‐Averaged Navier‐Stokes (RANS) equations, with a standard κ ‐ ε turbulence model. The Volume of Fluid (VOF) method is used to predict the discharge for a given forebay elevation. The model is used to evaluate the possible reduction of the spillway capacity during a Probably Maximum Flood (PMF) event. Flow field characteristics with and without the RSW structure are presented and discussed. The hydraulic force on the RSW structure is calculated.

Select this Article		Numerical Simulation of Floating Sluice Resistance Characteristics during Pulling Process Zong‐fu Fu and Zhong‐min Yan ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)464 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Floating sluice is a kind of friendly entironment hydraulic control structure. It's applying can solve effectively contradiction between river flood prevention and navigation. In this paper, a three‐dimension numerical flow model was established based on unstructured dynamic mesh technical. The model was predigested reasonably after the main factor of resistance was analyzed during pulling process and was validated with results of hydraulic model experiment. The relation between resistance per unit tonnage of floating sluice and rotation angle was obtained during opening and closing process of floating sluice. The influence on resistance of draft, rotation speed of floating sluice and flow velocity was analyzed and the method to determine the dynamic cabin capacity was put forward also.

Select this Article		Recent Advancements in River Flow Modeling Hyoseop Woo, Sung‐Uk Choi, and Won Kim ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)465 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Recent advancements in river flow modeling focused mainly on the ones made in Korea, encompassing 1D, 2D, and 3D models, are introduced. One of the main concerns in the 1D flow modeling has been to develop a new, robust method for simulating the discontinuous flow such as hydraulic jump. A new implicit upwind model with an appropriate treatment of the source terms has been proposed and tested to various discontinuous flows. This new model shows a very good stability and robustness compared with existing ones. A 2D river flow model has been recently introduced for simulating flows in the vegetated channel. In this model, the shallow water equations are solved numerically using the 2D characteristic dissipative‐Galerkin method. In order to take account of vegetative resistance, the drag force terms are included in the flow equations. The model is also capable of computing the morphological change in the river. The effect of gravity force due to geometry change and secondary currents are also considered in the model especially for simulating the bed elevation change in a bend. For 3D computations of the open‐channel flow, a Reynolds‐averaged Navier‐Stokes model has been proposed. The Reynolds stress model is used for the turbulence closure. The model has been applied to various types of open‐channel flows, including rectangular channel flows, partly‐vegetated flows, flows over smooth‐rough bed strips, and compound channel flows. Simulated flow structures are presented and compared with measured data in the literature.

Select this Article		Numerical Study for the Design of a Warm Water Fish Passage Adrian Strain, Marcela S. Politano, Troy Lyons, and Larry Weber ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)466 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A numerical study of the Prairie du Sac forebay was performed to better understand the flow field characteristics near a proposed downstream fish passage. The numerical model is based on the RANS equations together with a standard κ ‐ ε turbulence model. A field survey was performed to create a topographic representation of the Wisconsin River from the face of Prairie du Sac dam to 800 meters upstream of the dam. The effect of the fish bypass flow rate on the flow field close to the downstream fish passage was investigated. The fish bypass influence zone was calculated. Comparison between the velocity and acceleration fields near the bypass are presented and discussed.

back to top

OPENING INTRODUCTION: THE PURPOSE OF THE WORKSHOP

Select this Article		Control of Flow and Mixing in Environmental Flows Nikolaos D. Katopodes ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)467 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A new class of methods is presented for the control of environmental flows. The primary objective is the identification and containment of chemical spills in infrastructure systems. The approach is based on real‐time information provided by solid‐state microsensors installed at appropriate locations and capable of monitoring instantaneous changes in the concentration of several species in solution or suspension. The approach also utilizes concurrent flow and transport data provided by a simulation model based on continuous simulation of the system. Once an environmental event requiring control action is detected by the sensors, the model provides optimal directions to pre‐installed actuators capable of modifying the flow conditions in the flow domain. The technique requires assimilation of data from the sensors to steer the model, so the error between its present state and sensor measurements is minimized. The model also performs prediction simulations to determine the optimum set of actuator commands necessary to control the chemical plumes. The microsensors are constructed by combining custom electronic circuits with polymeric films. Several new approaches are tested at the interface between solid state technology and chemistry resulting in reliable and inexpensive sensor arrays. The new methods are tested in a variety of laboratory and large scale applications, and recommendations are made for the identifiability and controllability of general environmental flows.

back to top

SEDIMENT TRANSPORT MODELING

Select this Article		Modeling of Gravel Mining in the Rio Salado, Arizona Dong Chen, Ph.D., P.E., M. ASCE, Kumud Acharya, and Mark Stone ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)468 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Impact of sand and gravel mining on flood zone coverage and riverbed change of the Rio Salado, Salt River, Phoenix, Arizona were simulated using CCHE2D, a depth‐averaged two‐dimensional hydrodynamic and sediment transport model developed at the University of Mississippi. The bed material was treated as three layers on the channel bed with multiple grain‐sized sediment mixtures. Changes in bed elevation were calculated by solving the sediment mass conservation equation. The calculated results showed that the two‐dimensional model was applicable in simulating the impact of sand and gravel mining on flood zone coverage and channel geomorphology changes.

Select this Article		Study on the Instability Characteristics of Open Channel Hyper‐Concentration Flow Xu Haijue and Bai Yuchuan ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)469 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract It is widely existed in nature the flow carries with sediment, such as in Changjiang River, Yellow River, Zhujiang River and so on, in which, the flow in the middle and lower reach carries large quantity of sediment and appears to be unique characters of hyper‐concentration flow, such as the phenomenon of the suspended river over the ground, the seiche in its lower reach and so on. Aiming at these, the instability characteristics of the hyper‐concentration flow is studied in this paper. And it is shown in the analysis that, compared with the instability characteristics of the clear water (that is the single‐phase Newtonian fluid), not only Reynolds number is taken as the criterion to judge whether certain kind of flow is stable, but also some other parameters such as the sediment concentration, the suspending index and the particle diameter all become the factors that effects the instability characteristics of the flow, which makes the problem become even more complex. In this paper, three rheologic models are established respectively to study the flow with the coarse sediment (model for Newtonian two‐phase flow), the flow with large amount of fine sediment (model for non‐Newtonian two phase flow). The results show that the concentration of the sediment and the suspending index will make great influence on the instability characteristics of the flow, and two Newtonian two‐phase models give the similar results while the Non‐Newtonian two‐phase model gives the quite different ones, which are not mentioned in other papers. The results of the research can supply a scientific basis to the explanations of “slurrying river”, the turbulence intensity of the flow carries sediment and the variance of the turbulence structure.

back to top

STREAM MORPHOLOGICAL MODELING

Select this Article		1‐D Sediment Mathematical Model for Irrigation Canals of the Lower Yellow River Hongling Shi, Qingqi Tian, Qing Dai, and Ruqin Jiang ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)470 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Most irrigation districts along the Lower Yellow River, China, suffer huge sedimentation problems in the head area of irrigation system, including the headrace and settling basins. Thanks to the straight channel way and regular shape of canal cross‐section, a 1‐D sediment mathematical model was build to simulate and estimate the flow and sediment movement, the volume and distribution of sediment deposition, etc. The irrigation system is complicated with tree‐structure network in layout, artificially and disorderly control drainage, high sediment concentration, etc. A novelty practical function derived by analogy to simulate the sediment carrying capacity was adopted. This model was verified by the field data from the year of 1990 to 1999 of the large‐scale Weisan irrigation district, and the calculated result meets well with field data of flow, sediment concentration, sediment transportation and sediment deposition. Finally, some schemes of regulating operation for desiltation of the canal are put forward.

Select this Article		Modeling of Erosion and Deposition at Meandering Channels Yong G. Lai and Blair P. Greimann ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)471 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Straight rivers are rare in nature and meandering channels are commonplace. It is well known that a channel bed near the outer bank experiences erosion while the inner side is subject to deposition. The ability to predict and estimate the erosion and deposition at meandering bends is important for many water resource projects. Despite that a number of methods have been developed, recent trends are shifting to the process‐based multi‐dimensional models. In this study, a two‐dimensional depth averaged model is developed to predict the erosion and deposition for meandering channels. The model is first tested and verified using a laboratory channel bend with non‐uniform bed sediments. Good agreement is obtained including the prediction of the lateral sediment sorting. The model is then applied to a natural meandering bend on the Sacramento River.

Select this Article		Modelling Flow and Vegetation Effects in a Curved Channel Yafei Jia, Carlos Alonso, Andrew Simon, Robert Wells, and Sam S. Y. Wang ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)472 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Channel bank erosion devastates land of agriculture, contributes largely to the sediment yield from watersheds, and deteriorates the downstream channel morphology and water quality. An important part of the bank erosion is due to bank failure known to be related to many factors including properties of bank materials, porous water, roots of vegetation in the bank, and the hydrological process in the channel. However, bank erosion is also affected by the hydrodynamics of the channel flow, the shear stress due to the flow would erode the bed (bank toe) and the bank surfaces resulting in not only sediment yield directly but also more potential mass failures. In this study, the numerical models developed at the NCCHE, CCHE3D/2D, were applied to simulate the flow in a natural channel, Goodwin Creek, Northern Mississippi, with a complex topography. Vegetation effects were modeled, since woody vegetations occupy a large portion of the channel strongly affecting the flow distribution. In addition, the main flow, helical secondary current and the associated shear stress distribution in the main channel are affected by the flow from a side channel. This study is intended to resolve the 3D flow field and its associated shear stress distribution in this curved channel. The information of flow pattern and shear stress from the numerical analysis will be applied to bank erosion and channel change studies. Flow data, channel topography, and in‐stream vegetation condition were provided by the National Sedimentation.

Select this Article		Simulation of Morphological Evolution near Sediment Mining Pits Using a 1‐D Mixed‐Regime Flow and Sediment Transport Model Weiming Wu and Sam S. Y. Wang ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)473 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract In this study, a 1‐D model has been applied to simulate the flow through an initially dry mining pit and the associated sediment transport and morphology changes. This model uses the generalized 1‐D shallow water equations and non‐equilibrium sediment transport equations, considering the interactions between flow, sediment transport, and bed change. The governing differential equations are solved using the finite volume method with an upwind scheme for the intercell fluxes and the scheme of Ying et al. for the water surface gradient term. This model is capable of handling the mixed‐regime flows, so that the unsteady flow and sediment transport through the entire channel with a dry pit can be simulated. A total of 50 runs with varying pit lengths, pit depths, pit widths, channel slopes, unit flow discharges, and sediment sizes were simulated. The results from the 50 simulation runs were used to establish empirical envelope relations for the maximum headcut and tailcut depths and lengths. The established envelope relations can be used for channel stability analysis and mining pit design and management.

back to top

WATER QUALITY AND POLLUTANT TRANSPORT MODELING

Select this Article		2‐D Mathematic Model of Flow, Sediment, Temperature and Concentration Field and Its Application Zhang Jie and Zhang Xibing ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)474 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Based on the basic theories of sediment, flow movement and the diffuseness of temperature and concentration, a 2‐D mathematic model describing sediment‐carrying flow, temperature and concentration field used in reservoir, river channels and estuaries was established. The limit volume method and the finite element method were adopted to solve the control equations of 2‐D mathematic model. The calculation process of this model is stable and computational velocity quick. This model has been widely used in engineerings and detected by field observed results.

Select this Article		3D Numerical Simulation of Temperature and Concentration Field Zhanfeng Cui, Xibing Zhang, and Yaohua Dong ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)475 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Temperature and concentration field model based on 3D turbulent flow model are developed in this paper. In modeling, porosity and VOF method are used. Using the new model, flow field, the diffuse laws of temperature and concentration field around outfall are simulated. Based on the modeling, the 3D diffuse laws of temperature and concentration field around outfall were obtained. And the modeling can be used to simulate influence of warm water from power plant and diffuse of the pollutant.

Select this Article		CCHE2D Water Quality and Chemical Model Capabilities and Applications Tingting Zhu, Yafei Jia, and Sam S. Y. Wang ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)476 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract According to 1998 Clean Water Act Status by USEPA, sediments, pathogens, nutrients and metals are leading pollutants for rivers, streams and creeks. To study those water quality problems efficiently, it is necessary to develop a comprehensive model framework based on physical, chemical and biochemical processes. CCHE2D model has been developed for this purpose, which comprises of five independent models: two‐dimensional depth‐integrated hydrodynamic model, cohesive and non‐ cohesive sediment transport models, water quality (eutrophication) model and chemical fate and transport model. The eutrophication model simulates eight variables representing nitrogen, phosphorus, dissolved oxygen, and carbon cycles. The effect of suspended sediments on the phytoplankton growth is taken into account. The chemical fate and transport model simulates physical transport process and chemical fate processes such as sorption/desorption, evaporation, hydrolysis, photolysis, and bio‐degradation. Both models solve the transport equation. The numerical scheme has been verified using steady and unsteady analytical solutions. Models have been validated using field measurements. Their applications are shown in this paper as well.

Select this Article		One‐Dimensional Moment Model for Flow Movement and Suspended Sediment Transport Qingchao Guo ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)477 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract In current numerical models for flow movement and sediment transport, the equations widely used are depth‐averaged equations which are obtained at the price of sacrificing the information of hydraulic and sediment factors along the depth. To recover the vertical information, usually the 1D flow depth‐averaged equation has to be replaced by the 2D vertical model and the 2D depth‐averaged equations must be replaced by 3D equations. Such treatment will largely increase not only the computational effort but also the computer storage. In this paper, a set of new 1D depth‐averaged moment equations describing flow movement and suspended sediment transport in channels has been derived. The significant characteristics of this new model are that the equations can recover sufficient vertical information of flow and sediment factors without increasing spatial dimension. The theoretical verifications show that the proposed 1D moment model can reasonably simulate the vertical profiles for both velocity and sediment concentration. It is expected that the proposed moment model could improve the simulation ability of current depth‐averaged model very much and has a bright future in solving practical problems.

back to top

WATERSHED AND RESERVOIR MODELING

Select this Article		Calculation Models on Erosion and Deposition of Main Stem Tarim River and Its Analysis Wang Yangui, Ph.D. and Hu Chunhong, Ph.D. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)478 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Based on analysis on the cross‐section forms and the characteristics of water and sediment movement in flood plain and main channel, river cross‐section is divided into three parts: low‐water channel, main channel and flood channel. Water and sediment transport capacity is relatively small in low‐water channel; and it is larger in main channel which is suitable for water and sediment transport; as for flood channel, the discharge capacity is increased in spite of water and sediment transport capacity reduced. According to the field data for many years, the sediment transport rate is related to discharge in the following equation. Considering shortage of basic data and serious water losses (such as flood overflow, diversion, seepage and evaporation), a set of calculation models of water and sediment transport which would be applied to the different cross section forms (such as low‐water channel, main channel and flood channel) has been put forward based on the above derived sediment transport rate formula. Using those models, the erosion and deposition of the main stem Tarim River has been calculated and analyzed finally.

Select this Article		GSTARS3‐HTC Model Development and Evaluation as Part of the Lewis and Clark Lake Sediment Management Study Paul M. Boyd, Ph.D. P.E., Chih Ted Yang, Ph.D. P.E., Jungkyu Ahn, John W. Garrison, Daniel B. Pridal, P.E., John I. Remus, P.E., and Megan A. Lien ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)479 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The deposition of hydraulically transported sediments occurs in all flow impoundments, whether they be naturally occurring or man‐made. The natural system way of managing the deposition is to fill the impoundment with sediment until a point is reached where the flow of water finds a new path requiring less energy. This is very often caused by an impoundment completely or nearly full of sediment. If left in the current flow regime, Lewis and Clark Lake will eventually fill with deposited sediment, albeit more than 150 years in the future. The man‐made reservoir, Lewis and Clark Lake, formed by Gavins Point Dam, has existing uses that preclude merely allowing the reservoir to fill up. The lake is used for hydropower, navigation re‐regulation, recreation, water supply, and flood storage. In an effort to find ways to maintain all of the interests on the lake, management of the deposited sediments in the reach is vital. While the specific management process for the reservoir is yet to be determined, the Lewis and Clark Lake Sediment Management Study aims to develop tools to evaluate a wide variety of possible management proposals.

Select this Article		Model Development for Evaluating USDA Conservation Practices J. C. Ascough, II and M. J. M. Römkens ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)480 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract For many years the United States Department of Agriculture (USDA), through the Natural Resources Conservation Service (NRCS), has administered conservation programs to protect million of acres of land from degradation and to enforce environmental quality. The impact, effectiveness, and efficiency of these programs have not been quantified. The USDA‐NRCS has been instructed to quantify the existing environmental programs and/or design new programs to more effectively and efficiently meet the conservation goals of the U.S. Congress. Therefore, the NRCS and the USDA Agricultural Research Service (ARS) are currently leading a project to quantify the effects of the USDA conservation programs. The project, known as the Conservation Effects Assessment Project (CEAP), has two major components: (1) a National Assessment that will be conducted using NRCS data and watershed scale models developed by the ARS, and (2) the Watershed Assessment Study (WAS) which is concerned with detailed assessment of conservation programs on selected watersheds. The National Assessment will provide estimates of conservation benefits at a national scale. Two ARS models have been identified to make this assessment: SWAT (Soil Water Assessment Tool) and AnnAGNPS (ANNualized AGricultural Non‐Point Source). The National Assessment approach is to provide state‐of‐the art modeling capability for estimating conservation effects on a regional basis. The Object Modeling System (OMS) will be used to assist the development of these regionalized models. This system is in effect a modular modeling framework containing a library of simulation modules describing specific component processes. Depending on the nature of the dominant processes, components can be assembled under the OMS into a regionalized watershed model that best reflects the critical problems of the region under consideration. This presentation will discuss in broad outlines the CEAP program and the development of the OMS framework for use in regionalized watershed model development.

Select this Article		Numerical‐Simulation Based Multiobjective Optimization of Agricultural Land‐Use with Uncertainty Mustafa S. Altinakar and Honghai Qi ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)481 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Land‐use management has a direct impact on the environment and the ecosystem. Optimal agricultural land‐use management is a Pareto‐optimal compromise between conflicting technical, environmental and economical considerations. This paper describes multi‐objective optimization of agricultural land use‐management using TABU search method. For each trial scenario, multiple objective functions are constructed based on coupled simulation of AnnAGNPS watershed model, which computes the water, sediment and agrochemical loadings into streams, and CCHE1D channel network model, which simulates one‐dimensional unsteady channel network flow on erodible bed with non‐equilibrium transport of non‐uniform sediments, transport/fate of contaminants, and water quality. To account for parameter uncertainties and uncertainties in numerical model results, the combined objective function is calculated using fuzzy computation based on alpha‐cut techniques to obtain a membership function which yields not only a crisp value but also a range of variation. The proposed approach is tested using a hypothetical land‐use management study for the Goodwin Creek experimental watershed.

back to top

NETWORK CALIBRATION

Select this Article		A Comparative Study of Stochastic and Deterministic Sampling Design for Model Calibration Kourosh Behzadian, Abdollah Ardeshir, Fatemeh Jalilsani, and Farhad Sabour ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)482 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract This paper presents and compares two approaches, stochastic and deterministic sampling design, for the purpose of calibrating water distribution system model. Both approaches use a multi‐objective genetic algorithm known as NSGA‐II to identify the whole Pareto‐optimal front of optimal solutions. The relevant objective functions are to maximize the calibrated model accuracy and to minimize the number of sampling devices as a surrogate of sampling design cost. In the deterministic approach, optimal solutions are identified based on the assumed values for calibration parameters. However, the uncertainty of calibration parameters is taken into account in the stochastic approach with some pre‐defined probability density functions. Two different stochastic approaches, including noisy fitness function and Monte Carlo simulation, are considered in this study. The efficacy of considering stochastic sampling design rather than deterministic one is assessed by evaluating their objective functions in the simulation of 10000 sampling design problems, each of which is constructed with randomly generated calibration parameters. The stochastic approach is first test on an artificial case study. Then it is applied to a real world water distribution system known as Mahalat model in the central part of Iran. The results of comparison show significant improvements in optimal solutions when using stochastic approaches of sampling design.

Select this Article		Cadastral Misinformation and Its Effects on the Hydraulic Behavior of Water Distribution Networks and Their Models Calibration Juan G. Saldarriaga and Daniel Rodríguez ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)483 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract This article presents the results of a theoretical research on the effects cadastral misinformation on the simulation and calibration of Water Distribution Networks (WDN). It describes the developed methodology used to determine the effect that these mistakes have on the hydraulic response and calibration WDN models. Those effects were evaluated both for important pipes and different sets of unimportant pipes from the hydraulic point of view. The research proved that the Resilience Index is directly proportional to the effect produced by a mistake. In addition, the calibration methodology developed could be used to locate the cadastral mistakes. This means the hydraulic model could be used as a tool to improve water utilities WDN management. Finally, the methodology validated the use of skeletonized models.

Select this Article		Industrial Water Demand Management Model by Using Input‐Output Table and Strategic Decision Making with Uncertainty for Water Infrastructure Development Pongsak Suttinon and Nasu Seigo ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)484 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract In this paper, industrial water demand management model with strategic decision making model was developed. After assessment water demand with declared governmental policy and supply with water constraints in study area, one of interesting topic is whether water infrastructure project should be invested under uncertainty in the future. This paper shows that, with strategic decision making model, policy maker should make decision to construct new water supply with 10,525 million Thai Baht of benefit in 2016–2025. In case of without this decision model, the net benefit of project is −30,327 million Thai Baht in the same period or this project should not be invested. The main reason why this system should be applied is policy makers can choose the best way or maximum benefit in each water demand growth rate chance and make decision whether water project should be invested by using strategic decision making model with uncertainty in the future.

Select this Article		Use of Fireflow Tests in the Calibration of a Water Distribution System Model Tucker Southern, Walter Grayman, Leon Kjellgren, and Bryan Seppie ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)485 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Fireflow (or hydrant flow) tests are frequently used in the calibration process for water distribution system hydraulic models. In such a test, hydrants are opened and flowed at a high flow rate in order to cause high flows and large head losses in the pipes leading to the hydrant. When a system is stressed in this manner, the behavior of the distribution system is more sensitive to factors such as pipe roughness, closed valves, demands, and PRV settings. By comparing field measurements of flow and pressure to model results for the same situation, model parameters can be adjusted (calibrated) to better represent the system behavior. As part of a master plan and hydraulic model development for The Joint Powers Water Board (JPWB) covering the Green River/Rock Springs/Sweetwater County area in southwestern Wyoming, fireflow tests and other field techniques were used to calibrate the detailed model. Approximately 30 fireflow tests were conducted as part of the calibration process. Additional operational information on the water system (water usage, tank levels, pump operation) was collected from the SCADA system. Subsequently, the hydraulic model was applied under the test conditions and parameter adjustments made to bring the model into better agreement with the field results. The method was found to be most effective in identifying unexpected closed valves, adjusting PRV settings and behavior, and to a lesser degree in adjusting roughness coefficients. The logistics, costs, practical experience and the calibration results are discussed herein.

back to top

NETWORK MODELING 1

Select this Article		Critical Parameters for the Reliability Of Municipal Storage Tanks Jakobus E. Van Zyl, Olivier Piller, and Yves Legat ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)486 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A stochastic analysis method for sizing municipal storage tanks based on reliability criteria is discussed. A sensitivity analysis was done to determine the parameters most critical for sizing tanks (and thus for tank reliability). The results show that daily variations in water demand to be the most critical parameter, followed by hourly variations in demand, the supply ratio, and then pipe failures. Further work is required on fire water before conclusions on its impact can be made.

Select this Article		Determining the Best Way to Model Distribution Flushing Thomas Walski, F. ASCE, Zheng Yi Wu, M. ASCE, Wayne Hartell, and Kris Culin ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)487 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Modeling of distribution system flushing consists of adding demands to the model to simulate the open hydrants and observing the response of the system. However, the details of setting up flushing events bring up a number of issues that will be addressed in this paper. Most models do not explicitly include hydrants and their laterals in the model but simulate flushing as occurring at junction nodes near the hydrants. The paper shows that most of the head loss during flushing occurs in the hydrant itself, primarily as a conversion of pressure head to velocity head. As such, the error involved in simulating flushing at a junction node rather than at the location of the hydrant or hydrant tap is small. This paper discusses modeling practice in planning flushing operation. Conventional flushing (i.e. with no valve operation) is shown to do an adequate job in flushing a system in most cases and modeling can help engineers to identify situation where unidirectional flushing can yield significant improvement or flushing by operating hydrants alone will not be successful.

Select this Article		Prioritized Rehabilitation of Water Distribution Networks Using Dissipated Power Concept to Reduce Non‐Revenue Water Juan Saldarriaga, Mario Moreno, Natalia Romero, and Oscar Cortes ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)488 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract WDN operation involves two main issues: pipes rehabilitation and reduction of NRW; both with large economical repercussions. This paper presents an algorithm developed by CIACUA which selects the most important pipes to be replaced in terms of reducing power dissipation inside WDN. Additionally, it finds an optimal alternative for WDN operators to plan system's rehabilitation in terms of the enterprise's economic benefits. This paper includes analysis of two case studies of WDN, one with a regular topography and another with strong topographic variability. In both cases the methodology proved successful.

Select this Article		Understanding the Impact of Biofilm Growth on Pipe Roughness M. F. Lambert, J. Brookes, M. Kildea, T. Grantham, and B. McFarlane ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)489 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract This paper will examine the increase in pipe roughness with time that can occur from biofilm build up in raw water, treated water and sewage pumping mains. Various methods exist which accurately predict the diameter of the pipe and the size of the pump needed for the most optimum and cost effective system. These methods use a specific range of pipe friction factors and it is assumed that this friction factor will represent the system roughness over the design lifetime of the system. However, pipes systems are subject to changes over time which can adversely affect performance and cause the system to run inefficiently. One of these changes is the build up of biological growth in the pipes and is most prevalent in systems used to transport raw or recycled water as the biofilms require nutrients to survive. Experiments were conducted in the hydraulics laboratory on small pipelines using raw water sources with high carbon content. The change in roughness and flow velocity were recorded with time. It was found that these biofilms can grow relatively quickly and depend upon initial flow velocity and turbulence in the pipe system. Experimentally observed growth curves are given to illustrate the rapid growth phase and then a maturing phase of the biofilm. Changes in the velocity illustrated that different ultimate friction factors can be achieved. Friction factors and equivalent roughness heights can be determined and compared with typical design values and also actual measurements of the biofilm thickness. Measurements over a range of Reynolds numbers of the friction factor of a fully developed biofilm illustrated that the friction factor initially decreased with increasing Reynolds numbers and then following a minimum value began to increase sharply with increasing Reynolds number. This behaviour can be explained by the thinning of the viscous sublayer and the exposure of the rough biofilm surface to the turbulent flow.

back to top

NETWORK MODELING 2

Select this Article		Accurate Demand Modeling for Surge Analysis Bong Seog Jung, Paul F. Boulos, Don J. Wood, and Douglas C. Howie ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)490 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Surge modeling is important to safeguard against breaches in water distribution systems integrity. Its primary use is to predict and eliminate potential weak spots. To be effective, application of surge modeling in decision making requires accurate formulation of nodal demands, which directly affect both flow and pressure conditions in the distribution system. In this paper, a comparative study of two distinct demand formulations for surge analysis is presented. The first formulation assumes that the demands are independent of local pressures and can be met under all operating conditions. This approach is normally referred to as demand‐driven (or pressure insensitive demand) analysis. In contrast, the second formulation expresses nodal demands as a function of nodal pressures and is termed head‐driven (or pressure‐ sensitive) analysis. Each method is encoded into an existing distribution system transient model and applied to an example network to effectively compare transient analysis results. Results show that under transient conditions both positive and negative pressure surges can drastically alter the local pressures and affect the demand magnitude that can be extracted at the network nodes. The demand‐driven formulation proved to be intrinsically inaccurate and may lead to overdesign of surge protection devices resulting in unnecessary additional costs. It is concluded that a pressure‐sensitive demand formulation should be utilized for surge analysis to properly assess the impact of pressure changes and produce more accurate and useful transient results.

Select this Article		Chlorine Decay and DBP Formation under Different Flow Regions in PVC and Ductile Iron Pipes: Preliminary Results on the Role of Flow Velocity and Radial Mass Transfer Y. Jeffrey Yang, P.E., Christopher A. Impellitteri, Robert M. Clark, P.E., Roy C. Haught, Donald A. Schupp, P.E., Srinivas Panguluri, P.E., and E. Radha Krishnan, P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)491 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A systematic experimental study was conducted using a pilot‐scale drinking water distribution system simulator to quantify the effect of hydrodynamics, total organic carbon (TOC), initial disinfectant levels, and pipe materials on chlorine decay and disinfection by‐product (DBP) formation. The first phase of the experiments focused on the variables of flow rate and pipe materials and their effects on the formation of trihalomethanes (THMs) a primary category of DBPs in chlorinated drinking water. Different from previously reported bench‐scale investigations, this experimental study was to determine chlorine decay and DBP formation kinetics under simulated field conditions and to contrast the effects of new PVC and aged ductile iron pipe materials. In this paper, we report the experimental findings on the rate of THM formation under stagnant, laminar, transitional and turbulent conditions, and further attempt to address the effects of the pipe materials on the reaction kinetics. The results indicate that the second‐order DBP formation model of Clark (1998) can sufficiently describe the variations in total trihalomethanes (TTHM) concentrations. The determined reaction constants are smaller under stagnant and turbulent flows in the new PVC pipes than the aged ductile iron pipe. The latter has a high rate of DBP formation accompanying with rapid chlorine residual loss. It is suggested that these observed differences are a result of the mass‐transfer enhanced wall demand in the aged ductile iron pipe. Implications for re‐chlorination in the distribution network operations are discussed.

Select this Article		Distributed Network Fusion for Water Quality Mark W. Koch and Sean A. McKenna ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)492 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract To protect drinking water systems, a contamination warning system can use in‐line sensors to detect accidental and deliberate contamination. Currently, detection of an incident occurs when data from a single station detects an anomaly. This paper considers the possibility of combining data from multiple locations to reduce false alarms and help determine the contaminant's injection source and time. If we consider the location and time of individual detections as points resulting from a random space‐time point process, we can use Kulldorff's scan test to find statistically significant clusters of detections. Using EPANET, we simulate a contaminant moving through a water network and detect significant clusters of events. We show these significant clusters can distinguish true events from random false alarms and the clusters help identify the time and source of the contaminant. Fusion results show reduced errors with only 25% more sensors needed over a nonfusion approach.

Select this Article		Effect of Demand on Energy Use in Municipal Water Distribution Systems Santosh R. Ghimire, S. M. ASCE and Brian D. Barkdoll, F. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)493 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Energy use is of growing concern in the world in light of global climate change. Municipal water distribution systems (MWDS) use energy for pumping water. In this paper seven realistic MWDSs were modeled with varying user demands to quantify energy usage. It was found that the relationship between normalized demand and energy usage was linear and the curves for all seven systems analyzed collapse onto a line. In addition, in the range of water conservation of up to 20%, this linear relationship was almost a perfect line and suggested that 14% energy savings was realized by a 20% user demand reduction.

back to top

NETWORK OPTIMIZATION

Select this Article		A New Algorithm for Water Distribution System Optimization: Discrete Dynamically Dimensioned Search B. A. Tolson, M. A. Esfahani, A. C. Zecchin, and H. R. Maier ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)494 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The Dynamically Dimensioned Search (DDS) continuous global optimization algorithm by Tolson and Shoemaker (2007) is modified to solve discrete, single‐objective, constrained Water Distribution System (WDS) design problems. The new algorithm is called Discrete Dynamically Dimensioned Search (DDDS). DDDS characteristics parallel those of DDS, namely that it is a simple, parsimonious and efficient global optimization algorithm. This paper evaluates DDDS in relation to Ant Colony Optimization (ACO) and Genetic Algorithms (GAs) for WDS optimization. The first implementation of DDDS, called DDDS‐v1, was developed and then applied to the Hanoi (HP) and New York Tunnels (NYTP) benchmark WDS optimization problems without algorithm parameter‐tuning and with a simple parameter‐free penalty function approach. DDDS‐v1 results are good for the NYTP in comparison with published ACO and GA results. DDDS‐v1 identified the best known solution to the NYTP in 5/20 optimization trials. For HP, DDDS‐v1 generated better average results than any ACO and GA results available from a previous study. Importantly, DDDS‐v1 had no trouble finding the feasible region and returned final solutions from this region that were on average improved relative to other algorithms. Overall, findings suggest that DDDS shows good potential as a new tool for WDS optimization.

Select this Article		A Proposed Flow Path Model for Scheduling Optimization of a Water Distribution System Wei‐Chen Cheng, Nien‐Sheng Hsu, and William W.‐G. Yeh, Hon. M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)495 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A flow path model is developed for scheduling optimization of a water distribution system. The model simultaneously describes a water distribution system in two parts: (1) the water delivery relationships between suppliers and receivers and (2) the physical water delivery system. In the first part, the model considers waters from different suppliers as multiple commodities. This helps the model to clearly describe water deliveries by identifying the relationships between suppliers and receivers. The physical part characterizes a physical water distribution network by all possible flow paths. The advantages of the proposed model are that: (1) it is a general methodology to optimize water distribution, delivery scheduling, water trade, water transfer, and water exchange; (2) no simplifications are made for either the physical system or the delivery relationship; and (3) it can be used as a tool for real‐time decision making for scheduling optimization. The model optimizes not only the suppliers to each receiver but also their associated flow paths for supplying water. This characteristic leads to the optimum solution that contains the optimal scheduling results and detailed information of water distribution in the physical system. That is, the water right owner, water quantity and its associated flow path of each delivery action are represented explicitly in the results rather than merely an optimized total flow quantity in each link. The proposed model is first tested on two hypothetical water distribution cases. The results show that the flow path model has the ability to optimize both the quantity of each water delivery as well as the flow path. The model is being applied to the water distribution system of the Metropolitan Water District of Southern California (MWD), which supplies water to 18 million people in Southern California.

Select this Article		Honey‐Bee Mating Optimization (HBMO) Algorithm for Optimal Design of Water Distribution Systems Golnaz Jahanshahi and Omid Bozorg Haddad ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)496 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract This paper presents a novel evolutionary and meta‐heuristic algorithm known as honey‐bee mating optimization (HBMO) algorithm for the optimal design of a water distribution system. HBMO algorithm is a search‐based optimization algorithm that mimics the mating behavior of honey‐bee. Optimal design of a water distribution system is defined here as the identification of appropriate commercial diameters for the pipes of the system while satisfying the minimum required pressure head at all nodes for consumers and meeting velocity limits with the objective of minimizing the total investments. The algorithm uses EPANET software for the hydraulic simulation of the network. The performance of the algorithm is tested and verified on a well‐known network in the literature as “New York Tunnel” water distribution system. The results obtained are compared to the ones obtained by other optimization methods in the literature. The comparison shows the capability of the proposed algorithm to identify the near optimal solution. The time being spent for the convergence of the algorithm is considerably short rather than the other optimization algorithms. This result would be promising for applying the proposed algorithm to real world water distribution systems, compared to other evolutionary algorithms.

Select this Article		Tradeoffs in Water Distribution System Design for Normal versus Emergency Flows: Quantity, Quality, and Costs/Benefits Kelly Brumbelow and Elizabeth Bristow ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)497 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Prior research has identified a suite of mitigation methodologies to improve water systems' resilience against accidents, natural disasters, and terrorist attacks which simultaneously disable the water distribution system and start an urban fire. The results of vulnerability analyses and mitigation scenario evaluation recommended enlargement of critical water main sections in order to improve fire suppression effectiveness by increasing water flow to fire hydrants. This recommendation for optimal emergency response can potentially conflict with guidance on optimal water main sizing for daily water use. This work investigates a variety of alternative water main sizing strategies to determine the optimal combination of design for emergency response and day‐to‐day water quality requirements. These strategies are evaluated by testing them on the Micropolis virtual city model under both normal and emergency conditions in order to gauge their effect on a realistic water system. An analysis of the costs and benefits of each design strategy informs the study's final recommendations on optimal water main sizing and water system design to meet water system demands under differing use conditions.

back to top

NETWORK RELIABILITY

Select this Article		Prioritising Individual Water Mains for Renewal Yehuda Kleiner and Balvant Rajani ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)498 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The statistical analysis of historical breakage patterns of water mains is a cost effective approach to discern their deterioration, where physical mechanisms that lead to their deterioration are often very complex and not well understood. Furthermore, data required to model these physical mechanisms are rarely available and prohibitively costly to acquire. Several models exist in the literature, which use various statistical methods to analyse patterns of pipe breakage histories. Some of these models were designed to address relatively large groups of pipes, which are presumed to be homogeneous with respect to their deterioration patterns, while others address individual water mains. However, predicting a breakage pattern in an individual pipe has proven to be quite a challenge and the validation of these models is generally done on the basis of aggregate breakage rate although the model purports to predict individual pipe behaviour. The structural deterioration of water mains and their subsequent failure are affected by many factors, both static (e.g., pipe material, pipe size, age (vintage), soil type) and dynamic (e.g., climate, cathodic protection, pressure zone changes). Dynamic factors can currently be considered only in a model that was designed to deal with pipe groups. While group deterioration analysis is important for high‐level renewal planning, operational considerations require the prioritisation of individual pipe for renewal within such groups. Consequently, the National Research Council of Canada (NRC), with support from the American Water Works Association Research Foundation (AwwaRF) is investigating how to prioritise individual pipes within a so‐called ‘homogeneous’ group of water mains. Several approaches have been explored in this research initiative with various degrees of success. In this paper we describe the development of a non‐homogeneous Poisson model, which considers dynamic factors that can affect water main failure and some preliminary results are reported.

Select this Article		Simulation‐Based Localized Sensitivity Analyses (SaLSA) — An Example of Water Quality Failures in Distribution Networks Rehan Sadiq, Yehuda Kleiner, and Balvant Rajani ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)499 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Models for environmental, socio‐political, engineering and economic systems are typically complex due to a large number of interacting factors. Uncertainty and sensitivity analyses are integral parts of modelling complex systems. The level of uncertainties associated with any system increases with system complexity. These uncertainties are a result of vaguely known relationships among various factors (epistemic), as well as randomness in the mechanisms governing the domain (aleatory). Uncertainty analysis examines variations in the results that are imparted by the uncertainties in inputs, whereas sensitivity analysis determines the contributions of inputs. This paper discusses the identification of predominant input factors and ranking them using a technique called, Simulation‐based Localized Sensitivity Analysis (SaLSA), which is a hybrid of a ‘differential analysis’ and ‘simulation‐based sampling’ techniques. The proposed sensitivity analyses results are discussed using an example of water quality failures in distribution networks.

Select this Article		Survival Analysis of Water Distribution Pipe Failure Data Using the Proportional Hazards Model S. Park, Ph.D., J. W. Kim, A. Newland, Ph.D., B. J. Kim, and H. D. Jun, Ph.D. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)500 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract In this paper the hazard rates of the cast iron 6 inch (about 150 mm) pipes of a study area are modeled by implementing the proportional hazards modeling approach for consecutive pipe failures. A methodology of identifying individual pipes according to the internal and external characteristics of pipe is applied to a case study water distribution pipe break database. The individual cast iron 6 inch pipes are categorized into seven ordered survival time groups (STGs) according to the minimum total number of breaks recorded in a pipe. The modeling results show that the failure times of all of the STGs have the Weibull distribution. In addition, the estimated baseline survival functions show that the survival probabilities of the STGs generally decrease as the number of break increases for a given time. It is found that STG I has an increasing baseline hazard rate whereas the other STGs have decreasing baseline hazard rates.

Select this Article		Vulnerability, Risk, and Mitigation Assessment of Water Supply Systems for Insufficient Fire Flows Lufthansa Kanta, S. M. ASCE and Kelly Brumbelow, A. M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)501 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Water supply systems' vulnerability toward physical, chemical/biological, and cyber threats has drawn significant attention to their potential failure. These systems are critical not only because they must provide sufficient water for “everyday” municipal users but they also must deliver significant flows and volumes of water with high reliability during emergencies such as pipe failures, power outage, and fires. In this study, a methodology is developed to determine the vulnerable components of a water distribution system with respect to a fire event by utilizing a risk based optimization procedure. Using this methodology, vulnerability analysis is performed for a water supply system under three scenarios: (1) accidental failure due to soil‐pipe interaction, (2) accidental failure due to a seismic event, and (3) malevolent attack. Several mitigation strategies based on hardening of specific sets of water mains are evaluated through further simulation. Finally, the mitigation strategies are assessed with a benefit‐cost analysis to complete the system risk analysis.

back to top

NETWORK SECURITY: CONTAMINATION SOURCE IDENTIFICATION

Select this Article		Backward Probabilistic Modeling to Identify Contaminant Sources in a Water Distribution System Roseanna M. Neupauer, Ph.D., P.E., M. ASCE and Wesley H. Ashwood, S. M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)502 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract In this paper, we present an application of backward modeling to identify possible sources of a reactive contaminant in a water distribution system. In backward modeling the sensor location is treated as a source of probability, and the probabilities are propagated upstream and backward through time. The governing equation for the backward model is the adjoint of the forward transport equation. The adjoint state is related to probability density functions (PDFs) of the backward travel time which is the time in the past that contamination that was observed at a sensor could have been at an upstream node. It is possible to characterize prior positions of the contaminant using these PDFs. In this manner it is possible to identify possible release locations and release times upstream of the sensor location. A similar approach was used by Zierolf et al. to determine the point of origin, travel path, and travel time of chlorine arriving at a particular node in a distribution system. This method was expanded upon by Shang et al. to allow for storage tanks and multiple sources of water and chemicals to be taken into account. In this paper, an example water distribution system is analyzed using EPANET to identify sources of contamination.

Select this Article		Contaminant Source Characterization using Logistic Regression and Local Search Methods Li Liu, E. Downey Brill, Jr., G. Mahinthakumar, and S. Ranjithan ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)503 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Given a set of contaminant concentration observations at sensors in a water distribution network, an inverse problem can be constructed to identify the contaminant source characteristics (including location, strength and release history) by coupling a water distribution simulation model with an optimization method. This approach, however, requires a large number of time‐consuming simulation runs to evaluate potential solutions, and it may be difficult to converge on the best solution or set of possible solutions within a reasonable computational time. For this reason, it is desirable to appropriately reduce the decision space over which the optimization procedure must search to reduce the computational burden and to potentially produce faster convergence. We propose a method to reduce the decision space by efficiently identifying the probability of each point or demand node being a contaminant source location using mostly off‐line computations. Then, the most likely source locations are used as a good starting point for local search methods to obtain the optimal injection profile(s) to match the observed concentration profile(s) over time. The proposed approach is demonstrated for a contamination source identification problem using an illustrative water distribution network.

Select this Article		Source Identification for Contamination Events Involving Reactive Contaminants Jitendra Kumar, E. Downey Brill, S. Ranji Ranjithan, G. Mahinthakumar, and J. Uber ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)504 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The problem of contaminant source identification in a water distribution system can be solved as an inverse problem using a simulation‐optimization approach. The optimization method searches for contaminant source characteristics which lead to matching observations at the sensors. Accuracy of identification depends on the quantity and quality of data available at the sensors. The present state of the art in water quality monitoring sensors does not always allow for the detection of different kinds of contaminants in the system and they do not provide continuous contaminant concentration measurements. Some sensors provide an event detection trigger based on a specific concentration threshold yielding a binary detection/no‐detection signal. Sensors also routinely monitor water quality parameters such as chlorine and pH. For example, a contaminant present in the system may react with chlorine leading to changes in chlorine‐based water quality indicators. These anomalies (or deviations) in the observed water quality in the distribution system can be used as indicators of presence of contaminants in the system. A methodology for identifying the source characteristics using sensors outputting binary signals was presented by the authors recently. In the present study we investigate the interaction of reactive contaminants with chlorine in the system and its effect on water quality indicators. These anomalies indicating the presence or absence of contaminants will be used for determination of source characteristics using an evolutionary algorithm‐based simulation‐optimization approach.

Select this Article		Uncertainty Quantification of Contamination Source Identification Ami Preis, Lina Perelman, and Avi Ostfeld, M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)505 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The problem of contamination source identification is to disclose the characteristics of contamination source intrusions (i.e., injection location, starting time, mass rate, and duration). Several models and approaches were suggested to solve this problem. All previous studies assumed that the hydraulics of the system is known (e.g., pressures, flows, consumptions, tank water levels, etc.) where in reality only partial data is available. Uncertainty thus exists in revealing the characteristics of contamination source intrusions. The objective of this study is to suggest a method for quantifying this uncertainty. The methodology is comprised of two stages: at the first stage the inverse system's hydraulics problem is solved using the available measured and water distribution system's data, for identifying possible network flow patterns; at the second stage, using the outcome of stage one, possible contamination source characteristics are found. The uncertainty of the contamination source characteristics are quantified using the results of stage two.

back to top

NETWORK SECURITY: RESPONSE MODELING, DETECTION, RISK

Select this Article		An Agent‐Based Simulation‐Optimization Approach to Identify Threat Management Strategies for Water Distribution Systems Emily M. Zechman ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)506 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Threat management decisions in the event of contamination of a water distribution system must be tailored to protect public health, maintain fire‐fighting flows and flows to critical care facilities, and avoid inciting panic due to false alarms. Threat management strategies may be composed as a set of rules for taking actions to mitigate the situation and protect public health, such as flushing the water distribution system by opening fire hydrants or inducing demands, isolating portions of the system using control valves, and broadcasting boil water orders. These strategies must be robust to control contamination events that vary in time of injection, duration, and mass flow profiles, as well as to avoid false alarms. The development of threat management strategies can be improved through the use of a simulation‐optimization framework that simulates the complex interactions between managers' operation decisions, consumers' water consumption choices and the response of the hydraulics and contaminant transport in the water distribution system through mechanistic and dynamic methods enabled by agent‐based models. Heuristic optimization methods are coupled within the dynamic system simulation framework to allow identification of efficient threat management strategies to achieve public health protection and maintain acceptable service. These methods will be explored for an illustrative case study to identify strategies to achieve these objectives.

Select this Article		Optimal Hydraulic Response to a Water Distribution System Contamination Event T. M. Baranowski, Ph.D. and E. J. LeBoeuf, Ph.D. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)507 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The attacks of September 11^th spawned an increased awareness for the potential for intentional contamination of a water distribution network, resulting in reevaluations of emergency response plans by utilities across the country. Recognizing the need to determine appropriate response actions, the authors developed a prototype consequence management tool to address both planning emergency response scenarios and response to an actual emergency. Should a contamination warning system (CWS) detect the presence of a contaminant in a water distribution network, a variety of response actions must be examined in order to implement the most beneficial consequence management strategy, including public notifications and operational changes (e.g., valve closures and flushing). Employment of optimization techniques can be useful in determining the cost/benefit of isolating and/or flushing the system. Assuming an operational CWS and several hypothetical contamination scenarios, this paper will present modeling and simulation results to identify and evaluate potential utility response options to help mitigate the economic and public health impacts of a contamination release. In this work, the authors employ a genetic algorithm to select conventional and unidirectional system flushing programs that minimize a number of objectives, including total network contaminant concentration, total extent of contamination, difference between a maximum contaminant level (MCL) and the concentration of the contaminant in the network, and total mass of the contaminant consumed by nodal demand within the network. In addition, different injection locations will also be explored to examine network sensitivity to source location. Application of this technique to several simple networks demonstrates the usefulness of this optimization method as part of a consequence management strategy.

Select this Article		Risk Classification and Uncertainty Propagation for Water Distribution System Contamination Events Jacob Torres, Kelly Brumbelow, and Seth Guikema ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)508 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Previous efforts to apply risk analysis for water distribution systems (WDS) have not typically included explicit hydraulic simulations in their methodologies. A risk classification scheme is here employed for identifying vulnerable WDS components subject to an intentional water contamination event. A Monte Carlo simulation is conducted including uncertain stochastic diurnal demand patterns, seasonal demand, initial storage tank levels, time of day of contamination initiation, duration of contamination event, and contaminant quantity. An investigation is conducted on exposure sensitivities to the stochastic inputs and on mitigation measures for contaminant exposure reduction. Mitigation measures include topological modifications to the existing pipe network, valve installation, and an emergency purging system. Findings show that reasonable uncertainties in model inputs produce high variability in exposure levels. It is also shown that exposure level distributions experience noticeable sensitivities to population clusters within the contaminant spread area. The significant uncertainty in exposure patterns leads to greater resources needed for more effective mitigation.

Select this Article		Water Security Initiative Field Study: Improving Confidence in a Distribution System Model Reese P. Johnson, P.E., Victoria Blackschleger, Dominic L. Boccelli, Ph.D., and Yeongho Lee, Ph.D., P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)509 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The US Environmental Protection Agency (EPA) instituted the Water Security Initiative to design, deploy, and evaluate a model contamination warning system (CWS) for drinking water utilities. Through a cooperative agreement with the Greater Cincinnati Water Works (GCWW), the first pilot system has been designed and implemented in Cincinnati, Ohio. Deployment of this CWS relied on in‐depth understanding of the hydraulic and water quality parameters that exist in the GCWW's distribution network. As a result, a tracer test field study was designed as part of the pilot to assess the accuracy of the utility's distribution system model with particular emphasis placed on evaluating transport‐related aspects. This field study is considered to be the largest tracer test of a distribution network completed in the United States. Its purpose was unique in that the study was designed to test how well the model would predict conditions in the actual distribution system, rather than being designed to calibrate the model. The field study provided an unparalleled opportunity to improve our understanding of the predictive ability of a network model for representing transport within a very large, complex network. Our experiences are shared to provide any utility interested in improving its knowledge of, and confidence in, its distribution system model valuable insights into the necessary procedures, equipment, effort, and costs.

back to top

NETWORK SECURITY: SENSOR PLACEMENT

Select this Article		A Multi‐Objective Optimization Algorithm for Sensor Placement in Water Distribution Systems Mustafa M. Aral, Jiabao Guan, and Morris L. Maslia ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)510 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract In this study a multi‐objective optimization model is developed for water sensor network design in water distribution systems. In this model the three criteria used for evaluating the performance of the water sensor placement designed are directly used as the objectives of the optimization problem. These include minimizing the expected water volume contaminated, minimizing the expected time of detection and maximizing the detection likelihood. Due to the difficulty of determining sensor placement locations within thousands of junction combinations in the system, the sub‐domain concept is introduced, which identifies a subset of junctions for candidate sensor locations. The sub‐domains are determined using the roulette wheel method based on junction water demand values. The junctions with larger water demand have higher probabilities to be selected to the candidate sensor subset. For solution of the model an improved approach that is based on the non‐dominated sorting genetic algorithm (NSGA‐II) is used. The approach works over the sub‐domain and the final Pareto optimal front is obtained through the sub‐domain iteration process. The two water distribution systems provided in BWSN 2006 are chosen as examples to demonstrate the performance of the model and algorithm proposed. The impact of the non‐detected scenarios in calculating objectives on the Pareto optimal front is also addressed in this study. The results show that the proposed model and the algorithm are effective in solving this problem.

Select this Article		Low‐Memory Lagrangian Relaxation Methods for Sensor Placement in Municipal Water Networks Jonathan W. Berry, Erik Boman, Cynthia A. Phillips, and Lee Ann Riesen ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)511 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Placing sensors in municipal water networks to protect against a set of contamination events is a classic p‐median problem for most objectives when we assume that sensors are perfect. Many researchers have proposed exact and approximate solution methods for this p‐median formulation. For full‐scale networks with large contamination event suites, one must generally rely on heuristic methods to generate solutions. These heuristics provide feasible solutions, but give no quality guarantee relative to the optimal placement. In this paper we apply a Lagrangian relaxation method in order to compute lower bounds on the expected impact of suites of contamination events. In all of our experiments with single objectives, these lower bounds establish that the GRASP local search method generates solutions that are provably optimal to to within a fraction of a percentage point. Our Lagrangian heuristic also provides good solutions itself and requires only a fraction of the memory of GRASP. We conclude by describing two variations of the Lagrangian heuristic: an aggregated version that trades off solution quality for further memory savings, and a multi‐objective version which balances objectives with additional goals.

Select this Article		Probabilistic Approach to Characterize Contamination Sources with Imperfect Sensors A. E. De Sanctis, D. L. Boccelli, F. Shang, and J. G. Uber ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)512 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Sensor‐based contamination warning systems are being developed to detect intentional intrusion events and provide information on day‐to‐day performance of water distribution systems. Once a contamination warning system has detected contamination at one or more sensor locations, remedial actions should apply methods to identify the possible source locations. Current research on contamination source identification assumes that the information on contamination detection comes from perfect sensors. This assumption ignores the possibility of false positives (treating them as “true” events) and false negatives (treating every negative as though no event has occurred), which can presumably degrade effectiveness of remedial actions, and result in severe effects on public health. This research studies the impacts of imperfect sensor measurements (false positive or negative readings) on the contamination source identification. A probabilistic approach based on Bayes' theorem is applied to estimate the probability of each node in the water distribution system being a contamination source. Specifically, the probability of a paired location and time being a potential source is updated based on: 1) single or multiple sensor signals, which are dependent on the hydraulic connectivity determined through a flow path analysis model, and 2) the true and false reading information, which is dependent on background water quality and sensor behavior. Hence, the probabilistic state of a possible source can be iteratively modified in real‐time using an inference system that combines the previous knowledge and information from every new sensor reading in the network. A simulation study using a network with a hypothetical sensor system is presented to illustrate the time varying probabilities associated with the candidate contamination sources.

Select this Article		The TEVA‐SPOT Toolkit for Drinking Water Contaminant Warning System Design William E. Hart, Jonathan W. Berry, Erik G. Boman, Regan Murray, Cynthia A. Phillips, Lee Ann Riesen, and Jean‐Paul Watson ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)513 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract We present the TEVA‐SPOT Toolkit, a sensor placement optimization tool developed within the USEPA TEVA program. The TEVA‐SPOT Toolkit provides a sensor placement framework that facilitates research in sensor placement optimization and enables the practical application of sensor placement solvers to real‐world CWS design applications. This paper provides an overview of its key features, and then illustrates how this tool can be flexibly applied to solve a variety of different types of sensor placement problems.

back to top

NETWORK WATER QUALITY ANALYSIS

Select this Article		Increasing Application of Water Quality Models Nabin Khanal and Vanessa Speight, Ph.D., P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)514 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Hydraulic and water quality models of water distribution systems have served as the basis for several areas of research, development and application in the water industry. Faced with meeting more stringent federal and state rules utilities are finding water quality tools very useful for performing tasks such as computing water age, tracking disinfection residuals, predicting the vulnerability of water systems, locating optimal monitoring sites, developing a disinfection plan, and performing post‐incident forensic analysis. A well‐calibrated hydraulic model provides the basis for answering critical questions on facility operations and sizing. However, there is a growing need for assistance in understanding and interpreting results from water quality samples the utilities are monitoring. Operational data and hydraulic models can be used to develop a better understanding of water quality dynamics and initial recommendations for managing and improving water quality. Typical water quality complaints that utilities have to deal with on day‐to‐day basis include loss in disinfectant residual, complaints of taste and odor, colored water problems, and high concentrations of disinfection by‐products. When utilities examine sampling data, particularly for complaint sites, they are often left with more questions than answers. From which source did the water sample come from? Could the source of the problem be a particular facility? Why is there low residual at a particular location? What caused the increase in disinfection by‐products at a particular location? Water quality modeling results provides clues that can help to divulge such water quality dynamics of the system. GIS enabled water quality models facilitate mapping of model outputs allowing easy interpretation and quick comparison of modeling results. The graphical results are helpful in determining where disinfection booster location is needed, how DBP formation can be controlled, how different sources are blending in the system, and how water quality is changing throughout the network. Current water quality models have limited capabilities but new algorithms are being tested, mostly in research field, which can bolster the applicability of water quality models. Although fully calibrated water quality models require a high level of sophistication, less detailed tools are available to provide immediate insights into water quality dynamics of the system. This study summarizes how utilities throughout the country, small to big, are utilizing the water quality tools with different levels of sophistication to understand, manage and improve their water quality.

Select this Article		Realistic Representation of Water Age of Flow‐Through Reservoir in Drinking Water Distribution System Models Sean Xue‐Yong Zhang, Thomas Lane, and Hagop Shahabian ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)515 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Water age in a storage reservoir/tank can directly affect water quality within the reservoir and its service area. Reservoirs can be categorized as floating and flow‐through types, which are different in inlet/outlet configuration and flow passing through the reservoir. Most EPANET‐based drinking water distribution models represent reservoirs only as floating type reservoirs. Although floating reservoirs represent conventional elevated and ground storage tanks well in general, they can significantly overestimate water age for flow‐through type reservoirs. As an alternative, we propose to model a flow‐through reservoir as a group of parallel pipes with different diameters, plus a smaller floating reservoir. The resulted water age for flow‐through reservoir is more realistic. Modeling conservative tracer, chlorine residual and disinfection byproduct formation also benefit from this alternative representation of flow‐through reservoirs.

Select this Article		Water Distribution System Asset Deterioration and Impact on Water Quality — A Case Study P. S. Husband and J. B. Boxall ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)516 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract This paper reports on the results of a repeated uni‐directional flushing programme over a 4 year period as part of an asset maintenance study to prevent water quality failures through discolouration. By monitoring the resultant turbidity as accumulated material layers are eroded due to changes in system hydraulics it is shown that material regeneration/asset deterioration is a continuous, repeatable and therefore potentially viable modelling process. The monitored site had originally been selected following rehabilitation in 2001 which for the most part involved the scraping and lining of larger diameter cast iron pipes. The first monitored field study was 1 year after rehabilitation, the next a year later, then 2 years on and the final exercise a further year again. Flushing was conducted using a planned stepped increase in flow to assess the shear strength characteristics of the developing pipe wall particulate cohesive layers, primarily of iron and manganese composition in the UK, responsible for discolouration if mobilised. Once cleaned from the pipe walls it is hypothesised that the layers regenerate and are conditioned by the hydraulics found within the system. The results from the monitored pipe sections all show a similar and repeatable response to increasing system pipe wall shear stress, with each step mobilising additional material, corroborating the particulate cohesive layer approach to describing discolouration. Results also suggest that flushing was as effective as rehabilitation for controlling deterioration in this network and that the magnitude of a potential discolouration event is determined by the conditioning system hydraulics. These results can be used to inform operation and maintenance strategies to reduce the likelihood of a discolouration incident.

Select this Article		Water Quality Assessment during Distribution System Flushing Events K. A. Nilsson, S. M. Hooper, C. L. Moe, and J. G. Uber ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)517 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Water distribution system flushing events are a weekly and often daily occurrence used to improve water quality. This completed study monitored water quality parameters associated with 12 flushing events in a distribution system. Turbidity and pressure were continuously monitored for each flushing event, and 100‐liter large volume water samples were collected before, during and after each flushing event. The 100‐liter samples were analyzed for total coliform, fecal coliform, E. coli, heterotrophic plate count, P. aeruginosa, A. hydrophilia, C. perfringens, and coliphage to statistically characterize microbiological water quality associated with the flushing event. The study identified portions of the distribution system that had never been flushed, that were rarely flushed, that were regularly flushed, as well as locations at low and high elevations. The study results showed turbidity is very sensitive to fire hydrant valve operations, large volume water samples better represent the quality of water in the system than small volume samples, and total coliforms, P. aeruginosa, and A. hydrophilia analytes were found in pre flushing and flushing water samples which are indicative of the finished water quality and are an indication of regrowth potential in the distribution system.

back to top

CLIMATE VARIABILITY AND CHANGE IN WATERSHED PLANNING AND MANAGEMENT

Select this Article		Bayesian Inference of Non‐Stationary Flood Frequency Models T. B. M. J. Ouarda and S. El Adlouni ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)518 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract In this paper, the problem of fully Bayesian estimation of the extreme value model parameters is addressed. Extreme value models with covariates are an adapted tool to incorporate additional information given by dependence on the covariates or to represent trends in the time series. The Generalized Maximum Likelihood method (GML) is developed for the Generalized Extreme Value (GEV) and Generalized Pareto (GPD) models with covariates. In the GML method, the shape parameter of the GEV and GPD distributions has a Beta distribution as prior drawn for hydro‐meteorological variables. This prior distribution is considered to make inference for both distributions in the case of a model with covariates in a fully Bayesian framework. The reversible jump MCMC (RJMCMC) procedure is developed in order to carry out both parameter estimation and Bayesian model selection. Real and simulated datasets are used to illustrate the proposed methodology.

Select this Article		Conditioning Ensemble Streamflow Prediction Forecasts Using Climate Signals in the Midwestern U.S. David W. Watkins and Veronica Webster Griffis ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)519 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Assimilation of seasonal climate forecasts is widely recognized as a potential means of improving the accuracy and reliability of National Weather Service long lead‐time (1‐month to 1‐year) Ensemble Streamflow Prediction (ESP) forecasts. Such forecasts are not widely used, however, for a number of reasons. In the Midwestern U.S., few strong and consistent teleconnections have been identified for forecasting, perhaps due to nonlinear interactions of both Atlantic and Pacific Ocean patterns. Further, there is no consensus that the resulting forecast skill is sufficient to support water resources decision making. In this paper, we evaluate a set of climate patterns that may serve as useful indicators for seasonal (1‐ to 3‐month) streamflow forecasts in the Midwestern U.S. Streamflow persistence and predictability based on simulated soil moisture are used as benchmarks for comparison with climate‐based forecasts. Various procedures are discussed for assimilating climate forecasts into ESP forecasts, and forecast skill is assessed using re‐sampling procedures. Finally, the value of seasonal forecasts for water resources management applications is discussed.

Select this Article		Downscaling climate projections: A Method to Tackle Spatial and Temporal Variability Associated with Quasi‐Periodic Signals and First Two Statistical Moments Julio Cañón, Francina Domínguez, and Juan Valdés, F. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)520 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract In this paper we introduce a statistical downscaling method that incorporates the spatial and temporal variability associated with quasi‐periodic climate signals, such as ENSO, by using Multichannel Singular Spectrum Analysis (M‐SSA). In addition, the method preserves the expected values and variances of downscaled climate variables. The lump value of a climate variable is dissagregated over a grid of higher spatial resolution by using time series projections calculated on a cell‐by‐cell basis. To do this, we use a stochastic model consisting of the sum of the mean value, a quasi‐periodic component related to climate signals, and a random component associated with the residual variance of historic records. The technique is employed to downscale standardized precipitation values, from historic records and projections of coupled climate models, taking into account the variability associated with ENSO.

Select this Article		Incorporating Climate Change into Hydrological Data for Planning Models Messele Ejeta, Francis Chung, Sushil Arora, and Armin Munévar ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)521 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The current approach to study the effect of climate change in water resources planning considers determining and using signals of climate change that are based on the results of historical and projected general circulation modeling. These signals are computed for a predefined time step, such as a month, by using streamflow data that is based on model output for selected historical and projected climatological periods, such as 30 years. These signals are used to perturb historical hydrological data to obtain the hydrological data that incorporates climate change, which is then used for planning studies. This approach allows for the analysis of various assumed emission pathways and general circulation model results independently of one another. The approach generally shows the possibilities based on model results. Uncertainties surrounding emission pathways and general circulation modeling necessitate going beyond the possibilities to the study of the likelihood of climate change scenarios. This paper describes and discusses the current approach used to incorporate climate change in water resources planning, shows its limitations, and suggests possible approaches for future improvement.

back to top

CONFLICT MANAGEMENT AND DECISION MAKING I

Select this Article		Collaborative Modeling for Decision Making Christopher N. Dunn, P.E. and Robert A. Pietrowsky ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)522 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Demands for water resources continue to grow leading to increasing competition for remaining resources. The increasing competition leads to disputes as multiple stakeholders participate in the study process. A collaborative planning process, given many names (CADRe, Shared Vision Planning, Decision Support Systems, Integrated Water Resources Management, and Watershed or Systems Studies), is attempting to address disparate values and develop alternatives that improve upon initial goals. The question often asked is what role does computer modeling have during this collaborative process. This paper will address how to build trust in standard computer software. Different tiers of software fidelity and stakeholder engagement are proposed. In addition, visualization techniques used during the development of the model and the review of the modeling results will be stressed. An overarching interface can be used to integrate software that allows stakeholders to choose and use appropriate software thus enhancing trust. Finally, the paper will discuss how expert modelers will interact with non‐modelers in this collaborative process. Several examples of Hydrologic Engineering Center (HEC) software are used to describe how software can enhance the collaborative process.

Select this Article		Developing a Stochastic Conflict Resolution Model for Trading Discharge Permits in River Systems M. H. Niksokhan and R. Kerachian ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)523 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract So many researchers are preoccupied with optimal river water quality management to economically use the assimilative capacity in these systems. This paper presents an efficient methodology for developing pollutant discharge permit trading in river systems considering the conflict of interests of involving decision‐makers and the stakeholders. Moreover, the randomness associated with various input variables of the river water quality simulation model is considered. In the proposed algorithm, a trade‐off curve between objectives is developed using the Nondominated Sorting Genetic Algorithm‐II (NSGA‐II). The best non‐dominated solution on the trade‐off curve is selected using the Young conflict resolution theory. Finally, an optimization model provides the trading discharge permit policies. Applying this methodology to the Zarjub River system in the northern part of Iran shows that it can be effectively used for conflict resolution in trading water pollution discharge permits in river systems.

Select this Article		Evaluation of Sanitary Sewer System Vulnerability Jefferson Parish, Louisiana Jessica L. Watts and Eric D. Loucks ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)524 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Jefferson Parish is located in southeast Louisiana west of the City of New Orleans. For six months of every year (June through November), southern Louisiana is under threat of tropical storms, hurricanes, and associated storm surges. Most of the urbanized area within the Parish is low‐lying with extensive areas of land with elevations at or below mean sea level. This condition has required the construction of levees to protect against flooding from Lake Pontchartrain, the Mississippi River, and the Gulf of Mexico and also makes the area vulnerable to flooding from storms and hurricanes. Hurricane storm surges have the potential of flooding this area with water from the river and the lake, while hurricanes more severe than a fast moving Category 3 have the potential of compromising the flood protection levees in Jefferson Parish. In the wake of Hurricane Katrina's landfall on August 29, 2005, Jefferson Parish suffered significant damage to its infrastructure, particularly the loss of the major components of almost all its public utilities. Although few levees surrounding Jefferson Parish were breached, portions of the Parish were inundated with flood waters as high as eight feet, impacting sewer infrastructure. The Parish and its residents were without the services of basic utilities including water, sewer, and power for two weeks or more. This inoperability of the sanitary sewer pump stations was among the critical issues hindering the Hurricane Katrina recovery effort in Jefferson Parish. This paper describes the preliminary results of the damage analysis phase of the Jefferson Parish Long Term Sewer Mitigation Project (JPLTSMP). The JPLTSMP consists of a conceptual design and cost‐benefit analysis for different sanitary sewer pump station flood mitigation alternatives. The study attempts to pin point the weakest areas of the network to flooding as well as offer and evaluate solutions to those weaknesses.

Select this Article		The Role of Shared Vision Planning in Integrated Water Resources Management Paul Kirshen and Hal Cardwell ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)525 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Integrated water resources management is a complex process, but it is critical if global water challenges are to be addressed. Shared Vision Planning offers a process to address some of the most challenging portions of IWRM and moreover brings them all together; stakeholder participation, analysis, and building towards decision making. It also contributes to the processes of implementation and other planning elements.

Select this Article		U.S. Army Corps of Engineers Water Management for Environmental Sustainability James D. Barton, P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)526 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract As one of the nation's largest water resource agencies, the U.S. Army Corps of Engineers (Corps) manages over 600 dams located throughout the United States. These dams are operated for multiple purposes such as water supply, flood control, hydropower, navigation, recreation, and others. Throughout its history, the Corps has focused on being good stewards of the environment. To reaffirm it's commitment to the environment, the Corps issued a new set of Environmental Operating Principles in 2002 to guide its emphasis on improving environmental sustainability. The Environmental Operating Principles focus on improving environmental sustainability. The Corps also operates water resource projects in accordance with numerous other laws, regulations, and other guidelines focused on the environment. These include the Endangered Species Act (ESA), the Clean Water Act (CWA), and many others. In achieving environmental sustainability, a wide variety of different approaches are used. This paper will describe a broad range of examples of these efforts to manage water resource projects across the nation in an environmentally sustainable manner. The focus of the paper is to provide a sampling of efforts the Corps has recently been making to enhance the environment through various types of water management activities across the country. These efforts range from changing the project operations, to replacing equipment with new equipment that is more environmentally friendly. They include actions such as: (1) reallocating reservoir storage to maintain flows for fish and wildlife; (2) changing project operating criteria to improve conditions for fish and wildlife; (3) incorporating new equipment designed to improve water quality and fish survival; and other similar actions. The paper will also describe the effects of these efforts in terms of environmental restoration, hydropower generation, economic effects, and others.

back to top

CONFLICT MANAGEMENT AND DECISION MAKING II

Select this Article		A Case Study for Conflict Resolution in Reservoir Operation for Water Quantity and Quality R. Kerachian and E. Shirangi ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)527 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract In this paper, efficiency of a methodology proposed by Shirangi et al. (2008) is evaluated through a case study of the 15‐Khordad reservoir in central part of Iran using new objective functions. To obtain the utility functions of the domestic and agricultural sectors, which have conflict of interests, some decision‐makers and experts in these sectors have been interviewed. The Young adaptive bargaining theory is used for selecting the best solution on the trade of curve between objectives. The results show the methodology can be easily applied to real world reservoir operation problems with conflicting objectives.

Select this Article		Creating Diverse Habitat Environment in Ecological Water Resources Management Jian‐Ping Suen, Ching‐Nuo Chen, and Chih‐Heng Tsai ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)528 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Recent developments in instream flow methodology have shifted from minimum flow regulation to the regime‐based approach, recognizing that natural streamflow variation is an essential component in sustaining aquatic ecosystem biodiversity. However, when restoring streamflow variability within a water resources management project, it is difficult to precisely connect a specific species or community to its flow variability requirements. One alternate approach is to potentially promote aquatic biodiversity by increasing both the spatial and temporal habitat diversity of a river system. In this paper, a two dimensional numerical model is used to simulate depth and velocity distributions for multiple streamflow conditions at a stream section downstream of a reservoir. The model is based on depth‐averaged theory and is specific to an alluvial river with a movable bed. Fuzzy concepts are applied to modeled pools, riffles, and other habitat units — which are defined by depth and velocity — to assign approximately 290,000 mesh areas of the numerical model under different streamflow conditions. Both spatial and temporal habitat variation is evaluated to indicate which set of streamflow conditions maintains the more diverse habitat objective. This allows downstream flow‐based habitat diversity to become an ecological objective of reservoir operation.

Select this Article		Formulating and Scoping a Comprehensive Multi‐Jurisdictional Countywide Stormwater Management Program Joseph Sobanski, P.E., Daniel H. Lau, P.E., and John Murray, P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)529 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract In 2004, the Metropolitan Water Reclamation District of Greater Chicago (District) was given authority for stormwater management in Cook County, Illinois. The District began its stormwater management program by undertaking several key stormwater management planning activities, including conducting an institutional assessment, creating a new organizational structure, preparing a stormwater management plan, establishing a community participation framework, initiating detailed watershed planning and developing a comprehensive watershed management ordinance. Faced with the challenge of initiating major, concurrent watershed planning efforts, the District undertook a number of steps and activities to define an appropriate scope and level of effort for six major detailed watershed plans (DWPs) beginning with the Little Calumet River (LCR) watershed. This pre‐planning effort produced a two‐phased DWP approach that first defined the planning efforts and then developed the plans. The first phase quantified the available data, screened flooding problems, defined methodologies to resolve complex hydrologic and hydraulic (H&H) issues, formulated an appropriate alternative analysis approach, and established a framework for stakeholder participation in the watersheds. The second phase includes the H&H model development, alternative analysis and recommendations. This paper summarizes some of the key steps taken by the District to develop an appropriate scope and level of effort to prepare its DWPs and to meet the objectives defined under its stormwater management authority.

Select this Article		SVP as a Short Term Planning Tool: Preliminary Results of a Pilot Study William Cox, Hal Cardwell, and Alexey Voinov ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)530 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Shared vision planning encompasses the basic principles of traditional planning but differs from the conventional approach in its fundamental reliance on stakeholder collaboration in a process of mutual learning and discovery as facilitated by a collaboratively developed model of the system. This collaborative approach seeks to define issues and problems, identify values and interests, and explore alternative strategies for resolving conflict and solving problems. This paper reports on the preliminary results of a pilot study initiated by the U.S. Army Corps of Engineers' Institute for Water Resources to investigate the feasibility of SVP as a planning tool in a short‐term, small‐scale context in support of regulatory programs and local water planning. Experience with the pilot study conducted in the James River Basin of Virginia to date suggests significant challenges to application of SVP in a short‐term, small‐scale planning environment. Engaging a full range of stakeholders has been hindered by restrictions imposed by the short time frame, and scale limitations created stakeholder doubt about the validity and usefulness of the process. The fact that the pilot study was presented as a limited exercise caused it to be viewed as a threat to prospects for future, larger‐scale planning studies in the Basin. This experience illustrates the importance of pre‐existing conditions to the success of SVP and demonstrates the special challenges that impact use of SVP in situations involving limited time and scope.

back to top

FREQUENCY ANALYSIS OF LOW FLOWS AND DROUGHTS

Select this Article		A Decision‐Support System to Assess Surface‐Water Resources in Massachusetts Stacey A. Archfield and Richard M. Vogel ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)531 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Federal, State and local water supply, regulatory, and planning agencies require easy‐to‐use, technically‐defensible, decision‐support (DS) applications that can evaluate impacts of proposed water withdrawals, determine baseline streamflow conditions needed for sustainability of aquatic habitat, and estimate inflows to drinking‐water‐supply reservoirs for safe yield analyses at ungaged locations. An interactive, point‐and‐click DS application is developed in combination with a geographic‐information system to address these needs. The DS application estimates unimpacted daily streamflow at any user‐selected location — gaged or ungaged — on a perennial stream in Massachusetts. A new method is proposed to estimate a daily flow‐duration curve at an ungaged site by exploiting the strong structural relationship among streamflow quantiles. This method offers improvement — particularly for low flows — over traditional regression‐based approaches that relate flows at selected flow quantiles to measurable basin characteristics. A time series of daily flows is then created by transferring the timing of the daily flows at an index gage to the ungaged site at equivalent exceedance probabilities. Estimated daily streamflows show remarkably good agreement with observed daily flows and are generally comparable to the agreement obtained from a calibrated rainfall‐runoff model. A jack‐knife cross‐validation experiment indicates that the agreement between observed and estimated flow series at an ungaged site is also remarkably good.

Select this Article		Effects of Upstream River Flow Regulation on the Annual Low Flow Magnitude in the Savannah River at Augusta, Georgia, USA M. A. Samad, C. J. Talbot, and C. K. Turan ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)532 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The present paper investigates the effects of flow regulation on low flow conditions in the Savannah River at Augusta, GA before and after the construction of major dams and reservoirs. The Savannah River flow upstream of Augusta, GA is regulated by the operation of three large federal multipurpose projects: Hartwell Dam, Richard B. Russell Dam, and J. Strom Thurmond (also known as Clarks Hill) Dam. During low‐flow periods, the operation of the dams is controlled by the drought contingency plan of the Savannah River basin. Analyses of low flow statistics at the Augusta water level gauge indicate that trends in the low flow volumes and frequencies are significantly modified after the construction of the dams. Although water level data collected before and after the construction of the dams show homogeneous properties, the data show considerable heterogeneity because of flow regulation when the full data record is considered. Low flow statistics for the period after the construction of all three dams show the Log Pearson Type 3 distribution to be the most suitable. Flow distribution also shows a considerable increase in annual minimum daily‐mean flow rate compared to that prior to the construction of the dams.

Select this Article		Frequency and Duration of Drought in the Upper Green River Basin, Wyoming, USA John T. Bellamy, Glenn A. Tootle, Greg Kerr, and Larry Pochop ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)533 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The limited length of instrumental streamflow data impacts the true magnitude of natural interdecadal variability of water delivered from the UGRB. This limited period of instrumental record can be expanded by utilizing proxy records (reconstructed streamflow) derived from tree rings. Two reconstructed streamflow datasets are now available for the Green River near Green River, UT, and a new preliminary reconstruction has been developed for the Green River near Green River, Wyoming. Also, recent research has resulted in the development of nine streamflow reconstructions spatially located throughout the UGRB. The proposed research would use these streamflow reconstructions to assess patterns (temporal and spatial) and sources of streamflow variability in the UGRB. An investigation of long‐term streamflow variability, focusing on extreme events such as mega‐droughts, will be performed. The research will result in the development of probabilistic drought forecasts. Salas et al. provides drought definitions and equations that can be utilized by water planners in storage dependent systems. Loaiciga utilized the compound renewal process, which generalizes the Poisson process, to calculate return periods for drought events. This may result in frequency — duration curves for UGRB drought. Such probability curves can then be analyzed in light of Compact agreements to answer questions such as, “How often might the outflow from the UGRB fail to meet 10‐year delivery obligations?”

Select this Article		Investigating the Impact of Predictive Uncertainty in Rainfall‐Runoff Modelling on Storage Reliability Estimates Using Bayesian Total Error Analysis Mark Thyer, Benjamin Renard, Dmitri Kavetski, George Kuczera, Stewart Franks, and Sri Srikanthan ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)534 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract It is a common approach to extend streamflow records using longer term rainfall data and a calibrated rainfall‐runoff model. However, the impact that the predictive uncertainty in the simulated streamflow has on evaluating water resource systems, e.g. storage reliability, is rarely assessed. This is likely to be due to the lack of a robust framework for quantifying the uncertainty in the parameters and predictions of conceptual rainfall runoff (CRR) models ‐ which remains a key challenge for hydrological science. The Bayesian total error analysis (BATEA) provides a systematic approach to hypothesize, infer and evaluate probability models describing input, output and model structural error. This study utilizes results from a recent case study which critically evaluated the predictive uncertainty of BATEA compared to traditional calibration approaches (standard least squares (SLS) and weighted least squares (WLS)) and found that BATEA provided probabilistic predictions that are more consistent with the observations than both WLS and SLS. In this study, the sequent peak algorithm is used to estimate the storage reliability while accounting for the predictive uncertainty in the streamflow simulations. Comparing the results from BATEA, WLS and SLS it was found that for low demands the difference in the storage reliability estimates was minimal. However, as the demand increased, SLS and WLS tended to overestimate the storage reliability, relative to BATEA. This result has implications for common streamflow extension techniques and highlights that the predictive uncertainty in simulations needs to be taken into account when assessing water resource management options.

Select this Article		On Selection of Features for Regional Hydrologic Studies Shivam Tripathi, V. V. Srinivas, and Rao S. Govindaraju ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)535 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Feature selection is an important first step in regional hydrologic studies (RHYS). Over the past few decades, advances in data collection facilities have resulted in development of data archives on a variety of hydro‐meteorological variables that may be used as features in RHYS. Currently there are no established procedures for selecting features from such archives. Therefore, hydrologists often use subjective methods to arrive at a set of features. This may lead to misleading results. To alleviate this problem, a probabilistic clustering method for regionalization is presented to determine appropriate features from the available dataset. The effectiveness of the method is demonstrated by application to regionalization of watersheds in conterminous United States for low flow frequency analysis. Plausible homogeneous regions that are formed by using the proposed clustering method are compared with those from conventional methods of regionalization using L‐moment based homogeneity tests. Results show that the proposed methodology is promising for RHYS.

back to top

GIS APPLICATIONS IN WRPM I

Select this Article		Indicators of Hydrologic Stress in Massachusetts Sara Brandt, Richard M. Vogel, and Stacey Archfield ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)536 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A recent study in Massachusetts (Massachusetts Water Resources Commission, 2001) developed stress designations for all rivers within the state based entirely on available streamflow data from gaged sites. (This was the only electronic streamflow data available statewide at that time). This imposed three significant limitations on the 2001 stress designations (as was noted in the MWRC 2001 document at the time). First, the relative contribution of natural basin characteristics and human factors—such as water use—to low flows could not be distinguished. Second, ungaged basins could not be assessed. Third, since streamflow gaging stations are generally located on larger streams, the effects of water use on headwater streams could not be determined. The goal of the present study is to reassess the potential effects of human water use on streamflows in Massachusetts using newly available data and methods which enable us to estimate these effects in ungaged and headwater basins at very small spatial scales.

Select this Article		Limiting Imperviousness to Maintain Ecological Quality: Are Threshold‐Based Policies a Good Idea? Glenn E. Moglen ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)537 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The effects of urbanization on flows and water quality within a watershed have been documented for some time. Further, many models have been constructed that are sensitive to land use and land use change as predictors to make estimates of the impacts of urbanization. Impervious cover is probably the most basic quantity that can be used to quantify the degree and extent of urbanization across a landscape. Despite the apparent simplicity of recognizing imperviousness from the ground, measuring this quantity with accuracy from commonly available GIS‐based products is not trivial. The situation is further complicated if one takes the perspective of the hydrologist. What imperviousness value should be used in a given analysis method? Is all imperviousness created equally? Here we investigate the several methods for characterizing imperviousness from several perspectives: remote sensor measurement, inference from land use/land cover, and “direct measurement”. Our findings indicate that although different methods for measuring imperviousness are highly correlated, they can differ dramatically in their magnitude and there may exist local or systematic biases in the reported values associated with any one method. Therefore, if imperviousness values of 10% or greater are a concern, they are sensitive to the method used. As a final step, we illustrate how different measures of imperviousness can introduce error into a common hydrologic model — a regression model for peak flow estimation that uses imperviousness as a predictor. Peak discharge estimates generated from one measure of imperviousness averaged only 68.7% of those from a different measure. The implication is that it is imperative that methods for calculating and reporting imperviousness be standardized.

Select this Article		Runoff Prediction by GIS using Optimal Number of Rain Gauges D. Yeasmin and M. F. K. Pasha ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)538 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Finding optimal number of rain gauges to predict runoff without sacrificing any accuracy is important. Jackknife is an iterative technique of procedural removal of the data and finding its effect on final calculation. In this study, Jackknife method is used to remove rain gauges sequentially to observe their impacts on runoff. Precipitation surface is created by interpolation using available rain gauge data to calculate the runoff. Three interpolation techniques; Inverse Distance Weighting (IDW), Spline and Thiessen Weighting are used to create the precipitation surface. The effect of rain gauge removal on the runoff prediction is calculated by a statistical measurement which is a function of simulated and observed runoff. Methodology is applied both on uniform and non‐uniform types of precipitation distributions. It is found that while the required minimum number of rain gauges varies with the interpolation technique for non uniform precipitation distribution the number is constant for uniform precipitation distribution. Walnut Gulch in southern Arizona is considered as the study area.

back to top

GIS APPLICATIONS IN WRPM II

Select this Article		GIS Tools and Techniques for Analyzing and Modeling River Channel Data Venkatesh Merwade ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)539 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Anisotropic nature of meandering river morphology poses unique challenges in analyzing and modeling river channel data using GIS. Standard GIS tools that use Cartesian (x,y) coordinates are not appropriate for dealing with river channels because of their inability to handle river anisotropy. The objectives of this paper are to highlight the importance of river anisotropy in GIS analysis, and propose techniques and tools to handle river channels in GIS. A GIS toolset called GIS River Analysis Toolkit (RAT) is developed to compute river attributes, perform spatial analysis and communicate with external hydraulic models. The basic foundation blocks of GIS‐RAT are the geodatabase model which is inherited from ArcHydro, and the flow oriented coordinate system that honors river data according to the flow direction. Key functions in GIS‐RAT are discussed, and presented in this paper by using data from several rivers in the United States.

Select this Article		Real‐Time Water Budgets in South Florida Ron Mierau, Stephen Bourne, Ken Stewart, Kelly Brumbelow, Jack Hampson, and Joshua Peschel ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)540 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract One of five water management districts in Florida, the South Florida Water Management District (SFWMD) is responsible for regional flood control, water supply and water quality protection as well as ecosystem restoration in the Southern portion of Florida. Operationally, this responsibility translates to real‐time control of 168 water control systems (WCSs). Analogous to watersheds in most respects, the water control systems differ in that they have control structures to regulate flow between the systems and out of SFWMD boundaries. Efficient control of these structures ensures that the multiple objectives of flood control, navigability, water supply, and ecological health are met. As part of its efforts to meet its objectives, SFWMD is building an operational decision support system (ODSS) for control of its water‐control systems. The hydrological foundation of the ODSS is a water‐budget‐based real‐time assessment of system state, which is calculated by the WCS Tracker application. The WCS Tracker is an extension to ESRI's ArcMap software and receives as input: time series of gage and radar‐based rainfall, gage‐based evapotranspiration, and flow and stage measurement of the control structures. This paper will describe improvements in WCS Tracker calculation methodologies for real‐time water balance modeling, upgrades to algorithm performance, and improvements in user interface design. Specifically, (1) a “drying” model is introduced to estimate actual evapotranspiration (ET) from measured potential ET and catchment characteristics; (2) rainfall estimation based on NEXRAD data is shown to be superior to previous gage‐based values; (3) calibration of catchment parameters via novel procedures employing non‐parametric ranking of climatic state is introduced; and (4) a WCS aggregation‐disaggregation technique is shown useful for estimating term‐wise bias.

Select this Article		Spatial Rule‐Based Expert System for Sensor Network Planning in Rural Water Supply Systems, Kentucky Andrew Ernest, Karla Andrew, Ni‐Bin Chang, and Chi‐Han Cheng ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)541 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Meeting water quality and security objectives for a water utility is a challenging task. An Emergency Response Plan (ERP) for water supply systems is now required under the Bioterrorism Act of 2002 in the US. The need for thoughtful and comprehensive planning for prevention, mitigation, response and recovery from an event became even clearer recently. As part of this process, each US utility will incorporate the results of their Vulnerability Assessment (VA) into an existing or new ERP. This could result in a need to deploy a suite of sensors in the drinking water networks to replace the traditional manual sampling campaigns. However, rural communities that have very little resources might not be able to come up a solid ERP. The goal of this paper is to present the architecture of a spatial rule‐based expert system for decision support of sensor deployment in local water utilities. It presents the integration of knowledge acquisition of rule base and ontology of sensors for structuring an effective sensor network for two rural communities in Kentucky. VA for these rural water utilities can then be made possible with respect to the targeted chemicals and microorganisms in the tap water systems.

Select this Article		Water Quality Data and Simulation Model in GIS for the Rio Bravo/Grande Basin Carlos Patino‐Gomez, Daene C. McKinney, and David R. Maidment ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)542 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract In previous research, the Center for Research in Water Resources (CRWR) of The University of Texas at Austin, and the National Water Commission (CNA) of Mexico cooperated to develop the Rio Grande/Bravo database in which most of the data are referenced geographically (i.e., a geodatabase). The geodatabase consists of a Geographic Information System (GIS) and a relational database containing hydrologic, hydraulic and related data for the basin. The ArcHydro data model structure was used as the basis of the geodatabase since it allows the river basin to be represented in a realistic network of upstream to downstream connections. The ArcHydro data model defines attributes, relationships and connectivity between hydrologic features in a GIS database. Once the Rio Grande/Bravo geodatabase was created, it used in various water management agencies within the U.S. and Mexico. In this project, CRWR and CNA have cooperated to build on their previous results to accomplish three tasks: (1) add water quality data to the Rio Grande/Bravo geodatabase; (2) add water related infrastructure data to the Rio Grande/Bravo geodatabase; and (3) determine the main river segments in this basin to be used in water quality modeling. Also, some water quality simulations have been started for the rio Bravo/Grande basin, based on the water quality data model.

back to top

GV LOGANATHAN MEMORIAL TRACK ON RESERVOIR OPERATION I

Select this Article		Assessment of Watershed Nutrient Load Input to Reservoir, A Case Study Mohammad Karamouz, F. ASCE, Masoud Taheriyoun, Farzad Emami, and Behzad Rouhanizadeh ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)543 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Watershed modeling approach in water quality management and waste load estimation and allocation could be an effective way to improve the understanding of watershed‐scale pollutant transport. Factors such as topography, land slope, land use and hydrological and metrological conditions should be considered. Using watershed models has the advantage of evaluating the possible impacts of changes in management practices to reduce the pollutant loads. In this article Aharchai watershed in North‐western Iran has been modeled by Soil and Water Assessment Tools (SWAT), in particular, the nutrient load to Satarkhan reservoir is considered as an important element of the reservoir water quality. The model has been calibrated and validated for a three year field data. The results have been compared with the results of empirical models for estimating of non‐point source nutrient load. The results could be used to recommend policies to reduce nutrient load into the reservoir.

Select this Article		Conceptual Rule‐Based Storage Accounting for Multipurpose Reservoirs George F. McMahon, M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)544 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Rule‐based storage accounting can provide a framework for efficient and equitable allocation of benefits, costs and risks associated with operation and management of multipurpose reservoir systems. Sustainable management policies must accommodate (1) timely reallocation of storage in multipurpose reservoirs to most beneficial uses, and (2) creation of a system of credits and penalties for water management that incentivizes conservation, prevents cross‐subsidization among included purposes, and checks unsustainable demands. While storage accounting does not in itself allocate or prioritize uses of water, it does provide a mechanism for real‐time tracking of consumptive and non‐consumptive uses, and reservoir operations. By measuring system performance at all levels, rule‐based storage accounting thus discloses the efficiency, sustainability and fairness of water management policies, and in so doing serves to guide operational responses to changing hydrologic, socioeconomic and environmental conditions.

Select this Article		Improve Hedging Rules for the Operation of Lake Okeechobee in Southern Florida Jiing‐Yun You and Ximing Cai ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)545 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Hedging rule policies are designed to rationally allocate water resources over time. Previous study have addressed fundamental questions on hedging rules for reservoir operations including when, how much and how long to hedge. This study applies the theoretical findings of hedging policies to Lake Okeechobee in south‐central Florida to explore the potential of hedging rule policies for the operation of the reservoir. Lake Okeechobee is located in major water supply source to agricultural and urban users and the Everglades National Park in the southern Florida. The Lake also contributes to flood control, navigation, recreation, and fish and wildlife protection. Extensive studies, including those on hedging rules, have been conducted for the Lake. Water Supply and Environment (WSE) regulation, approved by the U.S. Army Corps of Engineers (USACE) and the Sothern Florida Water Management District (SFWMD) since July, 2000 is currently used to balance the different, usually competing objectives. Most recently the revised Tentatively Selected Plan (TSP) that is planned for implementation for a three‐year period beginning in late summer of 2007. Compared to WSE, TSP, a daily‐based regulation schedule with new bands, new release magnitudes, and new forecasting indices, is believed to be more effective in decreasing the risk to public health and safety, reducing damaging events and salinity violations to the estuaries, and increasing critical flexibility in the operation of the reservoir. Our study adopts an optimization model that maximizes water supply utility while, setting the regulation on flood control and environmental protection defined in WSP and TSP as “hard constraints”. We will first review the existing hedging rules used in WSP and TSP. To be realistic, this study attempts to improve the hedging rules within the operational context of WSE and TSP, rather than fully changing those schedules. It is expected to discover new knowledge that could help to improve reservoir operation in the real world.

Select this Article		The Future of Multiobjective Reservoir Management in the Potomac River Basin Mark Lorie and Erik Hagen ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)546 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The Potomac River Basin covers 14679 square miles between the Appalachian Mountains and the Chesapeake Bay. As with most other large river basins, the Potomac Basin has a diverse geography and serves many economic and recreational purposes. The lower portion of the basin includes the Washington, D.C. metropolitan area, and most of the water supply for this region comes from the Potomac River. The upper portion of the basin is predominantly rural, but includes many areas that are growing. In addition, the upper portion of the basin contains a significant agricultural industry, many stream sections prized for their fishing and Whitewater opportunities, a number of active and abandoned mines, and some industrial facilities. Two reservoirs in the headwaters of the Potomac River have a significant impact on the many uses of the river and on environmental conditions in the river. These reservoirs are operated primarily for flood control, and flow augmentation to support water quality and water supply. The current operational strategy for these reservoirs was developed in the 1980s when acid mine drainage was the primary water quality challenge. Since then, many of the acid mine drainage sources have been addressed and water quality has improved. At the same time, recreational activities on and below the reservoirs have increased and gained in prominence, especially fishing and white water boating. Because of the changing conditions, the Interstate Commission on the Potomac River Basin is working with the reservoir operators and stakeholders to study how operations can be changed in order to better balance needs within the basin. The study is based on a collaborative modeling approach known as Shared Vision Planning.

back to top

GV LOGANATHAN MEMORIAL TRACK ON RESERVOIR OPERATION II

Select this Article		Evaluating Reservoir Operations and Other Remediation Strategies to Meet Temperature TMDL's in the Willamette Basin, Oregon Thomas S. Lowry, Vince C. Tidwell, and Hal E. Cardwell ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)547 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Water managers in the Willamette River Basin face a number of difficult and closely interrelated challenges associated with the Endangered Species Act (ESA), the Clean Water Act (CWA), and other associated concerns. For example, under the CWA, the Oregon Department of Environmental Quality (ODEQ) has recently released a total Maximum Daily Load (TMDL) for temperature in the Willamette Basin. Some of the major factors impacting temperature in the Willamette include operation of the multiple reservoirs, permitted industrial and municipal discharges, land‐use types, and irrigation practices. Possible mitigation strategies include changes in land‐use to increase shading along streams, installations to cool or store point‐source discharges, changes in how and when water is released from the reservoirs, installation of multi‐port withdrawal structures on the reservoirs, and remediation of riparian and hyporheic zones. Each of these strategies comes with ecological, economic, and/or social costs and/or benefits that must be weighed and understood before meaningful dialogue about how to best manage the basin can occur. To address this problem a collaborative team from Sandia National Laboratories, the Institute for Water Resources, David Evans and Associates, and the Portland District of the Corps of Engineers have been working with stakeholders in the basin to design and collaboratively develop an integrated systems model of the basin to examine the linkages between the various strategies and their tradeoffs. The model domain includes the main stem of the Willamette, 7 major tributaries, and 12 USACE operated reservoirs. It is built as a series of system dynamics lumped parameter models, and provides real‐time feedback and scenario testing capabilities. Outputs from the model include changes in temperature at key monitoring points and costs per kcal of energy saved due to different remediation strategies, relative changes in nutrient loading and CO₂ emissions due to riparian shade planting, impacts on recreational opportunities and the economic impacts of those changes, and salmonid habitat suitability as it relates to temperature. This presentation will describe the technical collaborative processes in which the model was developed and how it will be used to inform reservoir operation and other policy decisions in the basin.

Select this Article		Evaluating Reservoir Operations in the Muskingum Basin Stuart M. Stein, Brett Martin, and Stephen R. Stout ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)548 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The Huntington District Corps of Engineers together with GKY & Associates, Inc. has developed a modeling tool to evaluate the effect of various changes in reservoir operations in the Muskingum River Basin. This modeling tool helps the Corps evaluate the trade‐off between potentially conflicting interests, such as structural safety, flood control, water supply, recreation, and ecology. This paper briefly describes the logic in the Muskingum River Basin Model, and shows the potential effect of two changes in reservoir operation.

Select this Article		Stochastic Linear Programming for Improved Reservoir Operations for Multiple Objectives in Burkina Faso, West Africa Derek Etkin, Paul Kirshen, David Watkins, Adama Alhassane Diallo, Gerrit Hoogenboom, M. Carla Roncoli, Judith Sanfo, Moussa Sanon, Leopold Somé, and Jacqueline Zoungrana ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)549 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A network of reservoirs and diversion structures in the Comoe River Basin in southwestern Burkina Faso, West Africa, provides municipal water supply and irrigation water for sugarcane agribusiness and a population of farmers. The region is characterized by severe intraseasonal and inter‐annual variability with respect to precipitation and reservoir inflows. Reservoir operations are generally conservative, even during wet years. A stochastic linear programming model is introduced which translates seasonal streamflow and precipitation forecasts, in the form of a scenario tree, into optimal release schedules for reservoir operators to implement in real‐time as forecasts and system conditions change. Goals include more efficient and equitable releases, and downstream flow maintenance. A VBA‐based graphic user interface (GUI) is used to ensure implementation and ease of use by operators.

Select this Article		The Value of Seasonal Climate Forecasts and Why Water Managers Don't Use Them David W. Watkins and Wenge Wei ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)550 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A number of government agencies and academic institutions now disseminate seasonal climate forecasts based on the output of general circulation models or statistical models developed from historical data. While verification of these forecasts often shows that they have significant skill, adoption by water management agencies appears to be slow. Some possible reasons for this are a lack of understanding of probabilistic forecasts, no straightforward means of revising policies based on forecasts, or simply a lack of will to depart from current policies and practices. We propose another reason, which is that in many locations seasonal forecasts are not reliable enough to warrant changes in operating policies. Through a simple economic‐optimization model, we show that forecast skill does not translate directly into forecast value, and in fact a surprisingly high level of skill may be needed to provide sufficient improvement in climatology‐based operating rules. One implication is that the skill measures commonly used to assess forecast accuracy and reliability may be inappropriate for water management applications.

back to top

INTERNATIONAL ISSUES

Select this Article		A Case Study on the Sustainable Development Indicators of Water Resources in Taiwan Horng‐Jer Shieh and Yu‐Ming Wang ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)551 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract This study establishes a sustainable development indicators (SDIs) system of water resources in Taiwan. The SDIs of water resources are based on Driving Force‐State‐Response framework, which was developed by the United Nations Commission on Sustainable Development. This framework is categorized into four dimensions: environmental, economical, social, and institutional. A total of twenty‐two SDIs of water resources in Taiwan from 1991 to 2004 are computed and evaluated. The results of study reveal the indicator scores for intensity of groundwater use, agricultural water use, and leakage rate of water supply pipelines are against the sustainability. To reduce groundwater use, agricultural water use and leakage rate of water supply is greatly needed to improve the sustainability of water resources in Taiwan.

Select this Article		An Environmental Security and Water Resources Management System Using Real Time Water Quality Warning and Communication for the Nile River Amir Ali Khan and Haseen Khan ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)552 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Through a NATO “Science for Peace” Project initiated in July 2007 an environmental security and water resources management system using real time water quality warning and communication is being researched and developed for the Nile River in Egypt. Real time water quality warning will be provided through a four station Real Time Water Quality monitoring index network. In parallel, an Egyptian Water Quality Index will be developed. This paper describes the project and describes the progress accomplished in the first year of the project. It describes the current water quality sampling network in Egypt and highlights how the NATO “Science for Peace” Project will build upon and augment the existing network. It highlights the challenges encountered in establishing the environmental security and water resources management system. The paper also describes how a key objective of the project is to train young scientists in Egypt. This research will be relevant to NATO concerns under the two categories of Environmental Security and Water Resources Management. The project will allow Egypt to ensure environmental security of its water bodies and enhance integrated water resources management.

Select this Article		Dam Operations and Malaria Transmission in Ethiopia: Evidence from Koka Jonathan Lautze, Paul Kirshen, Matthew McCartney, Solomon Kebrit, and Jeffrey Griffiths ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)553 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The creation of water reservoirs in regions of unstable malaria transmission often results in intensified malaria. Our work investigated the dynamics of this relationship around the Koka reservoir in Ethiopia. We first identified the degree to which malaria transmission is greater near the reservoir. We then determined that i) the greater malaria transmission resulted from greater mosquito abundance and ii) the most important mosquito larvae breeding site was the reservoir shoreline. Finally, we determined a relationship between rates of water level change and success of larval development, with subsequent consequences for malaria case‐rates. These findings have important implications for dam operation. The potential exists to modify the operation of the dam to greatly improve public health in the region, although inevitably there are trade‐offs with other reservoir objectives.

Select this Article		Improving Irrigation in Sri Lanka, Continuing 2000 Years of Irrigation Development Michael L. Jacobs, P.E., M. ASCE and Andy Constantaras, P.E., M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)554 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Sri Lanka has a history of irrigation dating back 2,000 years. Modern irrigation improvements began in earnest in the 20^th century, including hydropower development that satisfied nearly 100% of the electrical energy needs of the country. Rapid population growth, added power needs, inequalities in development nationwide due to almost continual civil unrest for the past 25 years, and cropping pattern changes stressed the existing reservoir, hydropower and irrigation system. The Government of Sri Lanka identified multiple hydropower and irrigation projects nationwide and requested assistance from the Millennium Challenge Corporation for funding. The US Army Corps of Engineers, Pacific Ocean Division and URS Group, Inc. assisted MCC with evaluating multiple irrigation projects within Sri Lanka for grant funding.

Select this Article		Irrigation Performance Improvement By Non‐Structural Measures — A Case Study From Bangladesh Md. Mizanur Rahman and D. S. Arya ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)555 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Potential performance of an irrigation project rarely attains its optimum level. The causes may be deterioration of physical condition of infrastructures, non‐optimal operation of water control structures, inadequate conveyance of the irrigation system, excess withdrawal at upstream, lacking of optimal managerial and operational irrigation schedule. The effect of these results reduced crop‐yield. The Meghna‐Dhonagoda Irrigation Project (MDIP) is one of the aspirant irrigation projects in Bangladesh. The Project area comprises 17584 hectares of which 14602 hectares are cultivable. Irrigation water is supplied by withdrawing water from river by two pump houses. The Project was implemented during 1978 to 1887. Since inception only 50% of irrigation performance was receiving from more or less reliable supply of water and the same was declining over the years. Among all constraints it was conceptualized that the practiced irrigation schedule and operational management were the main obstacles to attain its optimum result. It is found that over the total crop period the Crop Water Requirement (CWR) is considered as fixed depth of 265 mm/month, which causes the scarcity of water in the land preparation and flowering stages, on the other hand misuse of water in the matured and growing stages. The causes of this type of irrigation schedule is due to physically based problem of irrigation canal system, pump operation, land use and variety of cropping pattern in the same season. Since 2000, people's participation, a non‐structural measure has been practicing to overcome these problems. By people's participation irrigation performance was improved up to some extant (up to 70%). To attain the maximum potential irrigation performance, a new strategy of staggered cropping pattern, is recommended. Another non‐structural measure is Application of Decision Support System (DSS) for improvement of irrigation performance. A GIS based DSS, MDIP‐DSS, developed by Bangladesh Water Development Board (BWDB) in 2000, which integrates with MIKE‐11 HD and MIKE‐SHE models. With this MDIP‐DSS, an optimised scenario has been simulated for pump operation and gate operation of the water control structure for MDIP. Analysis shows the best simulation can increase the dependable irrigation index up to 82% and the highest average index up to 92% for high yielding variety Boro rice in MDIP. Combination of both of these non‐structural measures will give more improvement of the irrigation performances in any irrigation project.

Select this Article		Sharing a Multi‐National Resource Through Bankruptcy Procedures Majid Sheikhmohammady and Kaveh Madani ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)556 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Bankruptcy procedures are known as fair division methods applicable to monetary problems in which the total amount of the asset is not sufficient to cover the sum of the creditor's claims. These methods can be also used to solve natural resource allocation problems with the same characteristics in which the bargainers are willing to follow a cooperative approach rather than a competitive attitude. To show the applicability of these methods in water resources allocation problems, this study builds a bankruptcy model for the Caspian Sea negotiations in which five coastal states of Azerbaijan, Iran, Kazakhstan, Russia and Turkmenistan have been negotiating since 1993 without coming up with any agreement neither on the ownerships of waters, nor the oil and natural gas beneath them. In this problem, the total value of oil and natural gas which are currently claimed by the five littoral states is approximately 32 percent higher than the total value of proven and possible oil and gas located in the seabed of the Caspian Sea. The problem is how to determine a fair resource allocation which is associated with the legal status of the Caspian Sea. The developed bankruptcy model is solved with four different allocation rules including Proportional rule, Constrained Equal Award (CEA) rule, Contested Garment Principle, and Adjusted Proportional (AP) rule. Based on the shares of the bargainers under these rules, each party can rank the possible sharing methods. Finally, the study comes up with some recommendations on how to allocate this multi‐national water resource to the involved parties based on claims and preferences.

back to top

MANAGING WATER RESOURCES UNDER CONDITIONS OF GROWING DEMAND, CLIMATE CHANGE, AND NATURAL CLIMATE VARIABILITY

Select this Article		Climate Change Effects on Optimal High‐Elevation Hydropower Generation in Sierra Nevada, California Kaveh Madani and Jay Lund ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)557 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Climate warming is expected to shift the runoff peak from spring to winter in California as a result of the reduction in snowpack. The Sierra's high‐elevation system supplies roughly 74 percent of California's in‐state hydropower supply and is composed of more than 150 power plants with relatively small reservoirs associated with them. Such low capacity reservoirs have been designed to take advantage of snowpack, the natural reservoir. With climate warming, the adaptability of the high‐elevation hydropower system is in question as a shift in runoff peak can have important effects on generation and its economic value. A non‐linear optimization model employing historic hourly energy prices is used to explore energy generation of 137 hydropower plants in California's Sierra Nevada mountains for three climate warming scenarios (dry warming, wet warming, and warming only) over 15 years, spanning dry, wet and average hydrologic conditions. These results are compared to the historic generation to investigate the adaptability of Sierra's high‐elevation hydropower system to climate warming.

Select this Article		Modeling the Impact of Land‐Cover and Rainfall Regime Change Scenarios on the Flow of Mara River, Kenya A. M. Melesse, M. McClain, X. Wang, M. Abira, and W. Mutayoba ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)558 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The 13,750 km² drainage area of the Mara River basin includes the agricultural and forested areas in the upper basin, the open pastureland in the middle portion of the basin and the Masai Mara Game Reserve and the Serengeti National Park in the lower portion. Hydrometeorological analysis of the basin has shown a decline in the dry season flow and increase peak flood frequency in recent years. Changes in the precipitation pattern (distribution and volume), deforestation in the upper basin and increase water use activity in the large scale agricultural areas have been topics of discussion. This study applies the Soil Water Assessment Tool (SWAT) model to study the hydrologic response of the basin to the major hydrological input scenarios: land cover and precipitation regime changes for the upper portion of the basin. The adapted SWAT model was calibrated using daily flow (1980–90) data from the Amala and Nyangores gauging stations. Two scenarios (rainfall volume reduction by 20% for 2010–2030 period and conversion of the Mau Forest area to agriculture) were developed and used in the hydrological modeling. The model output indicated that, a 20% reduction in the rainfall volume translates to an average 46% reduction in annual flow at the Amala gauging station for the period considered. The forest‐to‐agriculture conversion of the Mau Forest, the water tower of the Mara River, yields only a 3.2% decline in the combined Amala and Nyangores river annual flow. Examining the low flows has shown that the base flow reduced during the dry seasons with the second scenario and this reduction was significant when rainfall decline was used in the simulation.

back to top

PMP, PMF, AND FLOOD FREQUENCY ANALYSIS: I

Select this Article		Bulletin 17B Flood Frequency Revisions: Practical Software and Test Comparison Results John F. England, Jr. and Timothy A. Cohn ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)559 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Bulletin 17B (B17B) provides guidelines for conducting flood frequency analyses in the United States (U.S.). Recently, the Hydrologic Frequency Analysis Work Group (HFAWG) began investigations to examine potential changes to B17B. The investigations have focused on alternative techniques for: (1) incorporating historical information; (2) addressing zero flows and low outliers; (3) use of improved plotting positions; and (4) providing correct confidence intervals. An overview of these efforts is presented, highlighting the Expected Moments Algorithm (EMA) with the log‐Pearson Type III distribution. Software that implements EMA is described. The existing B17B flood frequency approach is compared with an EMA‐based alternative using 82 U.S. peak‐flow data sets, data set resampling, and limited Monte‐Carlo simulation. In this paper, we highlight initial comparison results via a case study. The results suggest that the EMA‐based methods perform well when compared to the existing B17B approach, fit easily within the current B17B LP‐III/moments framework, provide much more accurate uncertainty estimates, and alleviate some technical and practical inconsistencies in B17B.

Select this Article		EMA with Historical Information, Low Outliers, and Regional Skew Veronica W. Griffis ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)560 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The Federal guidelines for flood frequency analysis described by Bulletin 17B employ three separate procedures to reflect historical flood information, to account for censored low outliers, and to introduce regional skew. Further, the identification of outliers and the moments of the final fitted log‐Pearson type 3 (LP3) distribution are dependent on the order in which these procedures are employed. Alternatively, the recently developed expected moments algorithm (EMA) for the LP3 distribution combines these three steps into one consistent analysis. Previous studies have demonstrated that EMA does as well as maximum likelihood estimators at estimating LP3 flood quantiles using historical information. EMA is also more efficient than the Bulletin 17B historically weighted moments algorithm, and can incorporate a wider range of historical information, including thresholds that were never exceeded, and floods whose values are described by intervals. Modest differences have been observed in the performance of EMA for low outlier adjustments relative to the Bulletin 17B conditional probability adjustment. Still, an analysis is needed of the performance of the EMA procedure which simultaneously employs historical information, regional skew information, and adjustments for any low outliers. A Monte Carlo analysis clearly demonstrates that this EMA estimator is more efficient than the Bulletin 17B estimator employing the same information.

back to top

PMP, PMF, AND FLOOD FREQUENCY ANALYSIS: II

Select this Article		A Regional Probabilistic Approach for Estimating Flood Probabilities Li‐Chuan Chen, A. Allen Bradley, and Jeffrey R. McCollum ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)561 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract In this study, we develop a statistical modeling framework to estimate the probability of flood threshold exceedances at arbitrary river locations within an area experiencing widespread extreme rainfall. Specifically, we derive a catalog of extreme rain events — defined as the occurrence of a 500‐year return period rainfall depth or greater at one or more precipitation stations — for the northeast region of the United States. The catalog is then combined with flood peak records from U.S. Geological Survey (USGS) stream‐gages to develop a regional logistic regression model for estimating flood probabilities. Various flood predictors (e.g., rainfall and site altitude) are explored to assess the effects. Results show potential use to evaluate probabilities of widespread flood events.

Select this Article		Flood Frequency Confidence Bounds — Art, Science or Guess!! Joseph D. Countryman, P.E. and Ben Tustison, P.E. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)562 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The current (Bulletin 17B) procedure for estimating confidence bounds for frequency curves assumes that the underlying distribution of flood flows is the Log Pearson type III (LP3) probability density function (pdf). The confidence bounds are estimated using a sampling error procedure. This can result in wild estimates of the confidence bounds which often exceed expected physical basin limits. A test of existing procedures was conducted. For this test, graphical frequency curves were developed from historical annual flood data for three (3) rivers in California. These curves were based on a minimum of 100 years of recorded data and incorporated additional information such as Probable Maximum Flood and Standard Project Flood estimates to ensure the graphical curves were grounded with physical hydrologic and meteorologic limits. These graphically estimated frequency curves were assumed to be the true underlying distribution of flood flows for each river basin. Synthetic records were generated by randomly selecting 100 sets of 100 annual maximum flows from the graphical curves (10,000 record years for each river). Bulletin 17B procedures utilizing a LP3 pdf were employed to calculate the best estimate and 90% confidence bounds for the 100‐year, 200‐year and 500‐year floods. This was done for all of the one hundred 100 year data sets and for an accumulative estimate (100 years, 200 years, 300 years, …, 10,000 years). For comparison, the same procedure was completed using the Pearson type III (P3) pdf. The results of the study show that estimating the extreme events (100‐year, 200‐year and 500‐year floods) using a predetermined pdf is subject to tremendous error and variability. Utilization of either LP3 or P3 distributions proved to be unreliable and ineffective. An alternate method based on a graphical frequency curve should be considered. Uncertainty in flood flows during the next 100 years should be assessed and a method based on sampling the graphical curve should be considered.

Select this Article		Models of LP3 Regional Skew, Data Selection and Bayesian GLS Regression Andrea M. Gruber and Jery R. Stedinger ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)563 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract As discussed in Gruber et al. Bulletin 17B employed by US Federal Agencies uses a skew map developed in 1974 by C. Hardison. With current computing power and advanced spatial statistical methods, a much improved skew analysis using currently available and much longer data sets is possible. This study employed the Bayesian Generalized Least Squares (B‐GLS) framework and diagnostic statistics introduced by Reis et al. with data from seven states in the southeast United States. This paper describes a the methods for identifying and screening for redundant sites corresponding to nested watersheds with similar drainage areas. Special attention is devoted to developing an improved cross correlation model of annual peak flows. The B‐GLS analysis demonstrates that regional skewness models can be highly accurate with a small model error variance and an effective record length in excess of 45 years.

back to top

QUANTIFYING UNCERTAINTY IN HYDROLOGIC AND HYDRAULIC SYSTEMS: I

Select this Article		Computationally Efficient Procedures for Uncertainty Assessment of Complex Environmental Models Christine A. Shoemaker ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)564 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract This paper describes some recent developments in uncertainty analysis algorithms. The description focuses on BOARS, a method that uses a mixture of optimization, Bayesian, and function approximation analyses. The BOARS publication shows that Markov Chain Monte Carlo (MCMC) analysis required more than 60 times as many simulations as did BOARS to get very similar results.

Select this Article		Incorporating Parameter and Data Uncertainties in the Analysis of Energy Drought Bertuǧ Akintuǧ and Peter F. Rasmussen ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)565 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The stochastic approach is commonly employed in the probabilistic analysis of water resources systems. In this approach, a selected stochastic time series model is used to generate synthetic series that mimic the important statistical properties of observed hydrological variables. Due to the use of limited amount of data for model estimation, the estimated parameters have sampling errors. This is usually referred to as parameter uncertainty. In multi‐site applications, the length of the observed records at different sites must be the same. In order to use all available data, the shorter series are extended using record extension methods. However, since extended data are not observed values, some data uncertainty is introduced. Although parameter and data uncertainties may have significant impact on the conclusions drawn from a study, they are neglected in most practical applications. In this study, an attempt is made to integrate and quantify uncertainty associated with parameters and extended data in the frequency analysis of energy drought for Manitoba Hydro, Manitoba, Canada. In the frequency analysis, a multivariate Markov‐Switching model is employed in the modelling of annual streamflow data. Parameter uncertainty is then incorporated in the Markov‐Switching model through Bayesian inference. In the Bayesian approach, the unknown parameters of the stochastic model are treated as random variables instead of fixed quantities. Parameter uncertainty is quantified by determining the posterior distribution of model parameters. Since the posterior distribution of the parameters cannot be derived analytically for the Markov‐Switching model, a Markov chain Monte Carlo (MCMC) method is used to numerically approximate the distribution. In the MCMC method, the extended data are also treated as parameters and simulated along with the model parameters in order to quantify the combined effect of data and parameter uncertainties in the frequency analysis of energy drought.

Select this Article		Integrational Operation Method using Stochastic/Neural Networks Models Sungwon Kim, Ph.D., P.E. and Hung Soo Kim, Ph.D. ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)566 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The goal of this research is to develop and apply the integrational operation method (IOM) for the modeling of the pan evaporation (PE) and the alfalfa reference evapotranspiration (ET_r). Since the observed data of the alfalfa ET_r using lysimeter have not been measured for a long time, South Korea, the Penman‐Monteith (PM) method is used to estimate the observed alfalfa ET_r. The IOM consists of the application of the stochastic/neural networks models respectively. The stochastic model is applied to generate the training dataset for the monthly PE and the alfalfa ET_r, and the neural networks models are applied to calculate the observed test dataset reasonably. Among the six training patterns, 1,000/PARMA(1,1)/GRNNM‐GA can evaluate the suggested climatic variables very well and also calculate the reliable dataset for the monthly PE and the alfalfa ET_r. Uncertainty analysis is used to eliminate the climatic variables of the input nodes from 1,000/PARMA(1,1)/GRNNM‐GA. The sensitive and insensitive climatic variables are chosen from the uncertainty analysis of the input nodes. Finally, the IOM is developed to model the monthly PE and the alfalfa ET_r with the least cost and endeavor.

Select this Article		Interactive Multi‐Objective Inverse Groundwater Modelling — Incorporating Subjective Knowledge and Conceptual Uncertainty Abhishek Singh, Douglas D. Walker, Barbara S. Minsker, and Albert Valocchi ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)567 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract This paper addresses the important question of uncertainty assessment for predictions obtained from an interactive multi‐objective groundwater inverse framework (proposed by the authors). This framework is based on an interactive multi‐objective genetic algorithm (IMOGA) and considers subjective user preferences in addition to quantitative calibration measures such as calibration errors and regularization to solve the groundwater inverse problem. Given these criteria the IMOGA converges to a set of Pareto optimal parameter fields (transmissivity, in this case) that represent the best trade‐off among all (qualitative as well as quantitative) objectives. Predictive uncertainty analysis for the IMOGA consists of assessing the uncertainty in the transmissivity fields found by the IMOGA, and the impact this uncertainty has on model predictions. To do this, we propose a multi‐level sampling approach, incorporating uncertainty in both large‐scale trends and the small‐scale stochastic variability in the transmissivity fields found by the IMOGA. The multiple solutions found by the IMOGA are considered alternative models of the large‐scale structure of the transmissivity field. Small‐scale uncertainty is considered to be conditioned on the large‐scale trend and correlated with a specified covariance structure. The prediction model is run using all simulated fields to obtain the distribution of predictions, which are then combined using model averaging approaches such as GLUE (generalized likelihood uncertainty estimation) and MLBMA (maximum likelihood Bayesian model averaging). The methodology has been applied to a field‐scale case study based on the Waste Isolation Pilot Plant (WIPP) situated in Carlsbad, New Mexico. Results, with and without expert interaction, are analyzed and the impact expert judgment has on predictive uncertainty at the WIPP site are also discussed. It is shown that for this case expert interaction leads to more conservative solutions as the expert compensates for some of the lack of data and modeling approximations introduced in the formulation of the problem.

Select this Article		Statistical Software Package Jeff Harris, Gary Brunner, and Beth Faber ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)568 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Over a period of many years, the Hydrologic Engineering Center (HEC) has supported a variety of statistical packages that perform frequency analysis and other statistical computations. Currently, the programs that receive the most use are HEC‐FFA (Flow Frequency Analysis) and STATS. HEC‐FFA performs Bulletin 17B analyses on peak flow data and STATS is used to perform a variety of analysis ranging from graphical analysis to flow duration analysis. Two other packages that are still supported are REGFRQ and MLRP. REGFRQ performs regional frequency analysis and MLRP is a multiple linear regression analysis tool. All of these individual pieces of software are currently being rejuvenated and incorporated into a single piece of software called Statistical Software Package (HEC‐SSP). In addition to incorporation of the existing software, additional capabilities are planned. These include coincident frequency analysis, duration analysis, and volume‐frequency analysis, among others.

back to top

QUANTIFYING UNCERTAINTY IN HYDROLOGIC AND HYDRAULIC SYSTEMS: II

Select this Article		Derivation of the Probability Plot Correlation Coefficient Test Statistics for the Generalized Logistic and the Generalized Pareto Distributions Sooyoung Kim, Younwoo Kho, Hongjoon Shin, and Jun‐Haeng Heo ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)569 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract The selection of appropriate probability distribution is important in frequency analysis to estimate the accurate quantile. Generally, the selection of appropriate probability model is based on the goodness of fit test. The probability plot correlation coefficient (PPCC) test has been known as powerful and easy test among the goodness of fit tests. In this study, the derivation of the PPCC test statistics for the generalized logistic distribution and the generalized Pareto distribution was performed by considering sample sizes, significance levels, and shape parameters. In addition, the correlation coefficients between orderly generated data sets and fitted quantiles were computed by using various plotting position formulas. Monte Carlo simulation was performed to select an appropriate plotting position formula for assumed probability distributions. As the results, the Gringorten's plotting position formula was selected for given distributions. Finally, the PPCC test statistics for given probability distributions were derived from correlation coefficient values based on the selected plotting position formula considering various shape parameters.

Select this Article		Evaluation of Uncertainties in Downscaling Precipitation Due to Climate Change Scenarios Mohammad Karamouz, F. ASCE, Sara Nazif, Sanaz Imen, and Mahdis Fallahi ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)570 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract There are considerable uncertainties in precipitation downscaling especially in considering climate change scenario effects. Evaluation of these uncertainties plays an important role in Integrated Water Resources Management (IWRM). Global Climate Models (GCMs) are the primary tools for climate change. There is considerable uncertainty in GCM simulations of climate change associated with: (i) uncertainty in future green house gas emissions and cycles that are usually simulated ‘off‐line’ (ii) uncertainty in the GCM response to model structure, parameterization, and spatial resolution. In this paper, the effects of using different climate change scenarios for precipitation downscaling are evaluated. Uncertainties in the downscaling model are also dependent on the input data and available observations for model calibration. For assessment of this aspect of uncertainties in precipitation downscaling, different periods of available data are used for model calibration. After developing 100 sets of ensemble data of downscaled precipitation for one hundred years, the probability distributions of downscaled values are determined and compared with the observed values. The results show that there are considerable uncertainties associated with the climate change scenarios and the input data of the model.

Select this Article		Gains from Copula‐Based Multivariate Distribution Functions for Rainfall Processes Hemant Chowdhary and Vijay P. Singh ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)571 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Study of multivariate character of rainfall processes is an important aspect for many hydrological applications. Modeling average storm intensity, duration and inter‐arrival time is useful for simulation studies and rainfall simulators. The correlation structure between rainfall intensity and duration has been found to have a significant effect on surface runoff. Bivariate exponential, bivariate normal, Box‐Cox‐transformed bivariate normal and bivariate Gumble distributions have typically been proposed and applied for fitting these processes. Such conventional distributions are restrictive in many ways such as having to use marginals from the same family of distributions and in having restrictions on the range of admissible dependence. Many conventional multivariate formulations involve Pearson's linear correlation coefficient, either directly or indirectly through its relationship with the association parameter. As it is not invariant to non‐linear monotone transformations, this correlation measure is not appropriate for deriving inter‐variate dependence characteristics. The concept of copula, which is relatively new in statistics, overcomes such limitations by allowing combination of different and arbitrary types of marginals and by offering a wider choice of dependence functions as well. Rank‐based copula approach also renders the copula method a desirable invariant property. Generation of multivariate random numbers employing the copula approach is a relatively easy procedure. This will help simulate many multivariate hydrological processes which hitherto were not able to be modeled on the basis of actual marginal distributions. Copulas are becoming increasingly popular in various fields, including finance, biomedical, reliability and engineering. A number of applications have been made in hydrologic engineering in which multivariate interdependence of variables is very important. A few copula formulations have been recently proposed for bivariate and trivariate rainfall frequency analysis, involving storm intensity and/or depth and duration. This paper presents a comparison of results from conventional and copula‐based bivariate frequency distribution analyses for storm intensity and duration. The gains from copula‐based approach are highlighted and comparison of results with those from a conventional method is presented.

Select this Article		Using Copulas for Stochastic Streamflow Generation Taesam Lee and Jose D. Salas ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)572 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract A copula is a multivariate distribution function with standard uniform marginal. Copula has been a useful tool for various problems in hydrology and water resources such as flood frequency analysis, drought prediction, and rainfall intensity‐duration frequency analysis. It allows modeling a multivariate distribution by separating it into its marginal distribution and Copula function. However, to the knowledge of the authors, it has not been applied for stochastic simulation of hydrologic data. In this study we explore the applicability of the Copula concept for stochastic streamflow simulation. Parametric (e.g. gamma) and non‐parametric (e.g. Kernel density estimation) functions are utilized for fitting the distribution of the original observed data and the serial dependence structure is modeled with alternative Copula functions such as Clayton, Frank, Gumbel, and Gaussian Copulas. The pros and cons of different copula time series models are investigated by comparing the statistics of the generated data. Two salient features of the Copula time series models include: (1) portraying the heteroscedasticity (heterogeneity of variance) embedded in the serial correlation of the observed data (2) the flexibility of applicable marginal distributions. The suggested copula models are applied to simulate synthetic yearly streamflow data of the Nile River. We examined the applicability of the gamma and Kernel density estimate as marginal distributions of the trivariate normal copula and compared their results against the LTARMA(1,1) model. The results showed that the benefits of using the referred copula models are quite marginal respect to the well known modeling procedures (e.g. the LTARMA). Perhaps the only significant difference is in better reproducing short term droughts (e.g. one or two year droughts), but as far as longer term droughts and storage capacity statistics no significant difference have been found.

back to top

QUANTIFYING UNCERTAINTY IN HYDROLOGIC AND HYDRAULIC SYSTEMS: III

Select this Article		Analysis of Uncertainty in Evaluation of Watershed Management Practices Mazdak Arabi, Rao S. Govindaraju, and Mohamed M. Hantush ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)573 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Utility of complex distributed‐parameter watershed models for evaluation of the effectiveness of non‐point source sediment and nutrient abatement scenarios such as Best Management Practices (BMPs) often follows the traditional {calibrate → validate → predict} procedure. Despite its simplicity, this approach is subject to non‐uniqueness of the calibrated parameter set. In this study, a computational framework is developed, in which investigation of uncertainty provides complementary quantitative and qualitative information in support of BMP evaluation. The Generalized Likelihood Uncertainty Estimation (GLUE) method is employed to generate a cumulative likelihood for sediment and nutrient outputs of the Soil and Water Assessment Tool (SWAT) for two scenarios representing outputs with and without representation of BMPs. Quantile analysis of the cumulative likelihoods yields expected sediment and nutrient loads as well as their corresponding uncertainty bounds. While comparison of expected values determines the effectiveness of BMPs, uncertainty bounds could be used to obtain a margin of safety (MOS) for such evaluations. The methodology was applied in a small watershed in the Maumee River basin. Maumee River is the longest river in the Great Lake system, where elevated levels of phosphorus have been a major concern. Results indicated that effectiveness of BMPs evaluated through the traditional method fell well between the estimated uncertainty bounds. It was concluded that parameter uncertainty accounted for nearly 15% of the variation in the estimated effectives of BMPs.

Select this Article		Application of Hilbert Huang Transform Method for Analysis of Contaminant Concentrations in the Niagara River Samuela Franceschini, S. M. ASCE, Christina W. Tsai, M. ASCE, and S. Ping Ho, A. M. ASCE ASCE Conf. Proc. doi:http://dx.doi.org/10.1061/40976(316)574 Online Publication Date: 10 December 2008 Full Text: \| Download PDF
	+ -	Show Abstract Water quality analysis and modeling in natural rivers has often been accomplished by monitoring programs and examination of the resulting series for long‐ and short‐term tendencies, seasonality and the relationship of the cause and effect of human activities. This paper introduces the HHT method to the environmental engineering field for the analysis and prediction of non‐stationary and nonlinear time series. The HHT combines two distinct analytical methods to decompose observed data into independent Intrinsic Mode Functions (IMFs), the Empirical Mode Decomposition (EMD) method and to transform these time‐dependant functions into time‐frequency functions, the Hilbert Transform method. The HHT is introduced to the field of water quality analysis for evaluation of trends and assessment of impacts of external physical factors for more sustainable river water quality management. A case study using the HHT method for data analysis and for simulation of time series of Chrysene concentrations in the Niagara River is presented.

Select this Article

Probabilistic Seasonal Water Supply Forecasting in an Operational Environment: The USDA‐NRCS Perspective

Thomas C. Pagano