Jump to Content

Increase text size Decrease text size

Search Content Type

Search
Advanced Search

Journal of Water Resources Planning and Management

Search Issue | RSS Feeds

RSS

Preview Manuscripts

ASCE journal Preview manuscripts are articles submitted through Editorial Manager then peer reviewed, accepted, and posted online before the final, copyedited version is published online and in print.
Click here for more information.

Add

Add Items to Cart

View

View Items in Cart

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

Select this Article		Assessment of Flow Changes from Hydropower Development and Operations in Sekong, Sesan and Srepok Rivers of the Mekong Basin T. Piman, T. A. Cochrane, M. E. Arias, A. Green, and N. D. Dat Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000286 Posted ahead of print 21 May 2012 Full Text: \| Download PDF
	+ -	Show Abstract The Mekong River supports unique biodiversity and provides food security for over sixty million people in the Indo‐Burma region, but potential changes to natural flow patterns from hydropower development are a major risk to the wellbeing of this system. Of particular concern is the ongoing and future development of 42 dams in the transboundary Srepok, Sesan and Sekong (3S) Basin which contributes up to 20% of the Mekong's annual flows and provides critical ecosystem services to the downstream Tonle Sap Lake and the Mekong Delta. To assess the magnitude of potential changes, daily flows were simulated over 20 years using the HEC ResSim and SWAT models for a range of dam operations and development scenarios. A 63% increase in dry season flows and a 22% decrease in wet season flows at the outlet of the 3S Basin can result from the potential development of new dams in the main 3S Rivers under an operation scheme to maximize electricity production. Water level changes in the Mekong River from this scenario are comparable to changes induced by the current development of Chinese dams in the Upper Mekong Basin and are significantly higher than potential flow changes from the proposed 11 mainstream dams in the Lower Mekong Basin. Dams on the upper sub tributaries of the 3S Basin have very low impacts on seasonal flow regimes because most of those projects are run‐of‐river dams and have small reservoir storages. Impacts on hourly flow changes due to intra daily reservoir operations, sediment movement, water quality and ecology need further study. Strategic site selection and coordinated reservoir operations between countries are necessary to achieve an acceptable level of development in the basin and mitigate negative impacts to seasonal flow patterns which sustain downstream ecosystem productivity and livelihoods.

Select this Article		Development and Field Validation of a Burst Localisation Methodology B. Farley, S. R. Mounce, and J. B. Boxall Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000290 Posted ahead of print 21 May 2012 Full Text: \| Download PDF
	+ -	Show Abstract Reducing water loss through bursts is a major challenge throughout the developed and developing world. Currently burst lifetimes are often long because awareness and location of them is time and labour intensive. Advances that can reduce these periods will lead to improved leakage performance, customer service and reduce resource wastage. In water distribution systems the sensitivity of a pressure instrument to change, including burst events, is greatly influenced by its own location and that of the event within the network. A method is described here that utilises hydraulic model simulations to determine the sensitivity of potential pressure instrument locations by sequentially applying ‘leaks’ to all potential burst locations. The simulation results are used to populate a Jacobian matrix, quantifying the different sensitivities. This matrix may then be searched to identify different instrument locations to achieve required goals: maximising overall sensitivity to all potential events or selective sensitivity to events in different network areas. It is shown here that by searching this matrix to optimise such selective sensitivity, while minimising instrument numbers, it is possible to provide useful burst localisation information. Results are presented from field studies that demonstrate the practical application of the method, showing that current standard network models can provide sufficiently accurate quantification of differential sensitivities and that, once combined with event detection techniques for data analysis, events can effectively be localised using a small number of instruments.

Select this Article		End‐To‐End Cyberinfrastructure for Decision‐Making Support in Watershed Management Marian V. Muste, M. ASCE, David A. Bennett, Silvia Secchi, Jerald L. Schnoor, M. ASCE, Andrew Kusiak, Nicholas J. Arnold, Sudipta K. Mishra, S. M. ASCE, Deng Ding, and Umashanker Rapolu Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000289 Posted ahead of print 21 May 2012 Full Text: \| Download PDF
	+ -	Show Abstract Over the past decade, water‐centric research has increasingly taken into consideration the interactions between the water cycle and the social, economic and bio‐geophysical processes that drive watershed dynamics. In parallel, water management has made great strides in data sharing and collaborative modeling that supports decision making through integrated planning and stakeholder involvement. Both research and management communities require data and simulation models that cover large spatial scales and workflows that enable investigations and decision‐making in real‐time with participation of multiple watershed actors.To efficiently accomplish their goals, these two communities are tapping into the capabilities of advanced cyberinfrastructure (CI) platforms that facilitate an understanding of watershed processes, knowledge management, visualization, interaction, and collaboration in multiple watershed science and engineering disciplines. The paper illustrates an implementation of an end‐to‐end CI system for understanding of the ecological threats, shifts in soil conservation practices, and public perception of environmental health with preservation of the economic benefits of agricultural production at the watershed scale. The systems were implemented in a 270 km² Clear Creek catchment in eastern Iowa.

Select this Article		Bayesian Networks for Source Intrusion Detection Lina Perelman and Avi Ostfeld, F. ASCE Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000288 Posted ahead of print 21 May 2012 Full Text: \| Download PDF
	+ -	Show Abstract Bayesian belief networks are graphical probabilistic analysis tools for representing and analyzing problems involving uncertainty. The problem of monitoring the propagation of a contaminant in a water distribution system can be represented using Bayesian networks (BNs). The presented methodology proposes estimating the likelihoods of the injection location of a contaminant and its propagation in the system using BNs statistics. A clustering method, previously developed by the authors, is first applied to formulate a simplified representation of the distribution system based on nodal connectivity properties. Given evidence from clusters, information is combined through probabilistic inference using BNs to find the most likely source of contamination and its propagation in the network. The conditional independence assumptions with the BNs allow efficient calculation of the joint probabilities and diagnostic and predictive queries (e.g. most likely event given evidence or the probability of an outcome given starting conditions). In addition, theoretic‐information measure is suggested to evaluate the significance of the clusters relying on the BN model of the system and possible suggesting optimal sensor locations. The proposed methodology is developed and tested on two water supply systems.

Select this Article		Evaluating the Impact of Alternative Hydro‐Climate Scenarios on Transfer Agreements: A Practical Improvement for Generating Synthetic Streamflows Brian R. Kirsch, Gregory W. Characklis, and Harrison B. Zeff Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000287 Posted ahead of print 21 May 2012 Full Text: \| Download PDF
	+ -	Show Abstract Utilities are increasingly considering the use of temporary water transfers to augment their supplies during periods of drought, an alternative that is often less expensive than expanding safe yields via new infrastructure. Understanding the volume and timing of transfers is important for developing contracts between buyer and seller, and can be challenging due to the transient nature of drought, a situation complicated by the uncertainties associated with climate change. While transfer arrangements have received some attention in the literature, the impacts of climate change on such agreements remain unexplored. This work investigates these impacts using an improved method for developing new hydroclimate scenarios. A technique for producing stochastic time series of inflows is described, one which effectively replicates the autocorrelation present in the historic record. Unlike autoregressive (and similar) models which assume complete stationarity, the mFGN method preserves the seasonal patterns in the correlation structure, thereby providing some advantages when modifying historical stream flow records to reflect alternative hydroclimate scenarios. Alternative scenarios are developed for the Research Triangle region of North Carolina, an area with several utilities currently seeking to use a system of risk‐based transfer agreements as a means to meet demand during droughts. This study simulates hydrologic conditions and transfer activity from 2010 to 2025 under a variety of climate scenarios. Results indicate that increased variability in inflows, with no change in the mean, corresponds to slight increases in transfer activity. However, when increased variability is paired with modest decreases in expected inflows (7%), transfer activity is doubled.

Select this Article		Dynamic Planning of Water‐Resource and Electric‐Power Systems under Uncertainty Q. G. Lin, G. H. Huang, G. C. Li, and J. B. Li Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000285 Posted ahead of print 21 May 2012 Full Text: \| Download PDF
	+ -	Show Abstract Hydro power plays an important role in electric power systems. It is not only interacted with many non‐hydro power generation activities, but also competes with other water users (industrial, commercial, residential and agricultural) for limited water resources. Therefore, the objective of this study is to investigate an optimized water allocation scheme within a water‐resource and electric‐power management system through developing an inexact water‐resource and electric‐power systems planning model (WPEM). WPEM is based on the interval‐parameter programming and mixed‐integer programming techniques, thus can deal with dynamics of capacity expansion and uncertainties associated with system management. The developed method is then applied to a power system with water‐shortage issues in the future. The results of scenario analysis indicate that WPEM could help get insights into trade‐off between system benefit and water utilization as well as that between system benefit and environmental concern. Thus, the modelling solutions could be used by water managers for supporting the effective allocation of water among power production, industrial process, agricultural irrigation, commercial activity and residential use in case of water shortage.

Select this Article		Simulation to Aid Disaster Planning and Mitigation: Tools and Techniques for Water Distribution Managers and Emergency Planners Elizabeth C. Bristow and Kelly Brumbelow Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000283 Posted ahead of print 21 May 2012 Full Text: \| Download PDF
	+ -	Show Abstract Communities depend on increasingly complex critical infrastructures to meet residents' daily needs and to facilitate emergency response. The potential for cascading failures could intensify the consequences of disasters and complicate the process of planning for effective emergency response. This article presents a methodology for conducting a vulnerability analysis based on simulation of water distribution's role in emergency response under various complex‐disaster scenarios in which incapacity of the water system is coupled with an urban fire. The analysis reported here was run on a virtual (but detailed and realistic) small town water distribution system, in order to permit candid discussion of the insights derived from the vulnerability analysis and to avoid disclosing the vulnerabilities of a real system. The analysis methodology presented may be adapted to fit the needs of real communities. The results of these simulations are used to demonstrate a procedure for designing and testing mitigation methods to improve the community's robustness and resiliency. Most of the mitigation techniques involve infrastructure upgrades, and a cost‐benefit analysis of these approaches is included as an aid to decision‐making. Discussion of how utility managers and emergency planners may adapt the analysis technique to their own systems is included throughout.

Select this Article		Vulnerability, Risk, and Mitigation Assessment of Water Distribution Systems for Insufficient Fire Flows Lufthansa Kanta and Kelly Brumbelow Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000281 Posted ahead of print 21 May 2012 Full Text: \| Download PDF
	+ -	Show Abstract Water distributions systems must reliably supply water for fire fighting needs as well as “everyday” demands but are vulnerable to a range of failure types that can compromise both functions. A methodology is presented integrating failure probability, risk analysis, and optimization of risk that can be used to assess system vulnerabilities and potential mitigation actions. To demonstrate multiple failure mode analysis, three failure types are included: accidental failure due to soil‐pipe interaction, accidental failure due to a seismic event, and malevolent attack. A risk optimization algorithm is implemented using dynamic programming to identify failure scenarios having greatest consequences and probability rather than focusing on just one aspect of vulnerability. Finally, potential mitigation strategies are assessed in a benefit‐cost‐risk reduction analysis. The methodology is intended as a practicable means for infrastructure managers to assess and address system vulnerabilities in a realistic and cost‐effective manner.

Select this Article		An Iterative Linearization Scheme for Convex Non‐Linear Equations: Application to Optimal Operation of Water Distribution Systems Eyal Price and Avi Ostfeld, M. ASCE Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000275 Posted ahead of print 27 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract Convex equations exist in different fields of research. As an example are the Hazen‐Williams or Darcy Weisbach headloss formulas and chlorine decay in water supply systems. Pure linear programming (LP) cannot be directly applied to these equations and heuristic techniques must be used. This study presents a methodology for linearization of increasing or decreasing convex non‐linear equations and their incorporation into LP optimization models. The algorithm is demonstrated on the Hazen‐Williams headloss equation combined with an LP optimal operation water supply model. The Hazen‐Williams equation is linearized between two points along the non‐linear flow curve. The first point is a fixed point optimally located in the expected flow domain according to maximum flow rate expected in the pipe (estimated through maximum flow velocities and pipe diameter). The second point is the calculated flow rate in the pipe resulting from the previous iteration step solution. In each iteration step the linear coefficients are altered according to the previous steps flow rate result and the fixed point. The solution gradually converges closer to the non‐linear headloss equation results. The iterative process stops once both an optimal solution is attained and a satisfactorily approximation is received. The methodology is demonstrated using simple and complex example applications.

Select this Article		Correction of the EPANET Inaccuracy in Computing the Efficiency of Variable Speed Pumps Angela Marchi and Angus R. Simpson Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000273 Posted ahead of print 27 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract One attractive possibility for saving energy in water distribution systems is the introduction of variable speed pumps (VSPs). However, to assess the cost effectiveness of using VSPs, a correct estimate of VSP energy consumption, and therefore efficiency, is essential. This task involves estimating the efficiency of various components: pump, motor and variable speed drive. Hydraulic solvers, which are used to check the hydraulics of the system, usually use the affinity laws to describe the pump behavior in a VSP pumping system. This paper demonstrates the inaccuracy of the popular hydraulic solver EPANET 2, which does not properly take into account the affinity laws in the efficiency computation when the speed changes for VSP operations. The correction of the code is presented and an additional improvement of the toolkit in order to directly retrieve the efficiency is introduced.

Select this Article		A Non‐Matrix Gradient Method for the Simulation of Water Distribution Networks E. Luvizotto, Jr, M. C. Cavichia, P. Vatavuk, and J. P. G. Andrade Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000271 Posted ahead of print 27 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract A new method is presented for the steady‐state analysis of water supply networks. This method is based on the same fundamental concepts as the gradient method with the difference that, for each element in the network, two approximations are made for the energy equation, one disregarding the head variation in the upstream node and the other doing the same for the downstream node. These equations, together with node continuity equations, provide an explicit method for determining the desired heads and flows without the need for the solution of a system of equations, as is commonly used for this type of analysis. Because the elements (e.g., pipes, valves and pumps) present the same type of treatment, the new method facilitates parallel processing. An illustrative example is presented for comparing the results obtained using the gradient method (implemented in EPANET) and the proposed new method.

Select this Article		Groundwater Resource Planning to Preserve Streamflow — Where Environmental Amenity Meets Economic Welfare Loss Jun Wan, Yi‐Chen E. Yang, Yu‐Feng Lin, and Jihua Wang Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000269 Posted ahead of print 27 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract Streams and associated biological communities are among our most valuable natural resources. Humans rely on the environmental services provided by streams in a myriad of ways. However, in some areas, excessive groundwater pumping exacerbates the already critical pressure on streamflow and needs to be managed through effective planning. Based upon economic and hydrogeological concepts, this study estimates the amount of streamflow depletion due to groundwater pumping and the negative impact on the socio‐economic system if groundwater pumping has to be constrained to restore streamflow. The main objective of this paper is to develop a multi‐objective non‐linear optimization model to simulate the tradeoffs between streamflow restoration and economic welfare loss in a Chicago suburban county ‐ McHenry County. The multi‐objective optimization is conducted at both county and municipality levels. An evolutionary algorithm, the non‐dominated sorting genetic algorithm (NSGA‐II), is used to solve the optimization model and to identify the tradeoff curve (or Pareto frontier). Comparing municipal Pareto frontiers shows spatially heterogeneous costs of preserving streamflow through various “shadow prices” and also the different capacities of restoring streamflow. We discuss the shapes of the Pareto frontier, the sensitivity of the pumping boundary constraints, and return flow coefficients. We conclude that the multi‐objective optimization model provides a useful framework to consider conflicting objectives in a typical environmental management and planning process, and that the findings can help decision makers and planners in formulating effective groundwater pumping strategies.

Select this Article		Recovering the Release History of a Pollutant Intrusion into a Water Supply System through a Geostatistical Approach Ilaria Butera, Fulvio Boano, Roberto Revelli, and Luca Ridolfi Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000267 Posted ahead of print 27 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract This work addresses the issue of recovering the release history of a pollutant injection in water distribution systems through the application of geostatistical tools. Geostatistical tools are here applied to the inverse problem of recovering the release history of a pollutant injected into a water‐distribution pipeline network. This application assesses the uncertainty in the concentration measurements and the release function by considering them as random variables characterized by their statistical moments. Performance of the geostatistical application to steady and unsteady flow conditions hinges on numerical modelling of the hydraulic behaviour of the water distribution system and evaluation of a transfer function that characterizes the probability of contaminant migration at control points in the network. A sensitivity analysis is carried out and it proves that the methodology is stable with respect to measurement errors and uncertainty in the network description (roughness coefficients and water demands). The analysis of error terms, the relative error of the released contaminant mass and the root mean square error of the recovered release function, demonstrates that the geostatistical methodology is able to characterize the release history of a contaminant in a water‐distribution pipeline system.

Select this Article		Heuristic Post‐Optimization Approaches for Design of Water Distribution Systems Manuel A. Andrade, Doosun Kang, Christopher Y. Choi, and Kevin Lansey Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000265 Posted ahead of print 27 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract This work presents a post‐optimization methodology for refining the solutions found by adaptive search algorithms used in the design of large water‐distribution networks. The approach employs two heuristics to search for an optimal combination of pipes that, after a reduction of their diameters, will maximize cost savings while continuing to meet design constraints. Adaptive search methods are often used to design urban water distribution networks when the number of pipes in the network is insignificant. For complex, real‐world networks, however, such methods are computationally demanding and they have difficulty finding near‐global optima. To identify a solution as close to the global optimum (and in which no pipe can be reduced without violating pressure constraints), requires a high‐speed computer potentially running for a long time and also probably some good fortune. The post‐optimization approach presented here is shown to be an efficient complement to heuristic search algorithms used in the design of real‐world networks. In a network created with the aid of a genetic algorithm, the proposed heuristics found that 4.37% of the pipes with a diameter above the minimum could be further reduced without causing hydraulic failure.

Select this Article		Developing an Agricultural Planning Model in a Watershed Considering Climate Change Impacts Mohammad Karamouz, Behzad Ahmadi, and Zahra Zahmatkesh Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000263 Posted ahead of print 27 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract Societies are facing major challenges in allocating water resources to growing water demands due to population growth, industrial and agricultural developments. With increasing water scarcity, the need to increase agricultural water productivity is receiving significant attention in developing countries. Among alternative options for meeting increasing water demand, improving productivity has received considerable attention. Therefore, planning of water systems to face future development conditions needs further studies on land, water use and resources as well as consideration of objectives to maximize crop production to achieve the maximum net return. Since climate change is likely to have impact on the hydrological cycle and consequently on the available water resources and agricultural water demand, there are concerns about the impacts of climate change on agricultural productivity. Considering climate change impacts, in order to optimize agricultural productivity, practical frameworks and models based on comprehensive researches and studies need to be developed. The goal of this study is to develop an agricultural planning model in order to optimize the cultivated area, crop pattern and irrigation efficiency based on the estimations of crop water requirements, water availability and water allocation to irrigation. For this purpose, Aharchay watershed located in the northwestern part of Iran is selected as the case study. For crop water requirement estimation, the output of HadCM3 AOGCM (Hadley Centre Coupled Model, version 3, Atmosphere‐Ocean General Circulation Model) is statistically downscaled and used as inputs to the CROPWAT model developed by FAO (Food and Agriculture Organization). Then water supply resources are assessed using a water allocation planning tool. The results of this study show the significance of integration and using different tools and methods in assessing and allocating water resource in regions with limited/scarce water resources.

Select this Article		Parambikulam‐Aliyar Project Operations Optimization with Reliability Constraints M. Mahootchi and K. Ponnambalam Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000261 Posted ahead of print 27 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract In this paper, a recently developed stochastic programming technique that includes reliability constraints is used to solve the operations optimization problem of the Parambikulam‐Aliyar Project (PAP), a multireservoir system in India. The use of reliability constraints as chance‐constraints in reservoir operations optimization have been around for some time but is still a challenging problem due to either (i) results are not good or (ii) cannot be applied in problems with more than one or two reservoirs when such techniques depend on discretization. The new implementation of chance constraints based on the Fletcher‐Ponnambalam model as extended to multireservoir systems provides better results than so far known. This work is easy to apply as it requires only a standard nonlinear programming solver.

Select this Article		The Value of Information in the Design of Resilient Water Distribution Sensor Networks Maud Comboul and Roger Ghanem Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000259 Posted ahead of print 27 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract The ability to monitor the flow as well as how water transforms throughout water networks would greatly improve the management of those distribution systems. The sensor placement problem attempts to find the locations of monitoring devices that would optimally observe water quality and protect consumers from accidents and intrusions of contaminants. In some related critical scenarios, the absence of information about possible contamination events including knowledge of the injection sources, contaminant types or mass and time of pollution as well as the variability of water network input parameters, such as the nodal demands and the pipe roughness coefficients, raises several challenges that must be addressed by the sensor network design process. In this paper, we describe a stochastic parameterization and analysis of uncertainty for the design of sensor networks aimed at maximizing the probability of detection of accidents and intrusions in water distribution networks. A challenge with such an approach, in particular when applied to large urban water networks, is the size of the ensuing computational model and the associated numerical optimization problem. This problem is compounded in the presence of uncertainty, where the need to deal with a large number of statistically plausible scenarios underscores the need for efficient yet credible algorithms for addressing the sensor placement issue. In addition to modeling aspects, we also address a challenge associated with the computational feasibility and performance of relevant numerical algorithms. Specifically, and through the use of submodular cost functions, we are able to solve the optimization problem with a greedy algorithm, yielding sufficient computational performance that allows us to describe stochastic water demands in the context of Monte Carlo simulations. We further account for imperfect sensors while maintaining submodularity. Our results show that the optimal sensor network layout is highly dependent on whether uncertainty in the stochastic parameters has been introduced and whether individual sensors can fail or not.

Select this Article		A General Multiobjective Model and a Simulated Annealing Algorithm for Waste‐Load Allocation Larice N. de Andrade, Geraldo R. Mauri, and Antônio Sérgio F. Mendonça Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000257 Posted ahead of print 27 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract Waste‐Load Allocation (WLA) is a difficult problem with multiobjective features that requires models that consider a full range of competing goals to identify good and practical solutions. In this study, a general and multiobjective optimization model was proposed. This model integrates different decision variables related to multiple waste removal efficiencies and outflow discharges into water bodies. Our model also considered an equity measure and limits for the concentration of dissolved oxygen and biochemical oxygen demand. A Simulated Annealing (SA) algorithm and the QUAL2E simulation model were employed to solve the WLA problem. This approach was applied to the Santa Maria da Vitória river watershed, located in the State of Espírito Santo, Brazil. Computational results have demonstrated that the proposed optimization model with the SA metaheuristic and QUAL2E could effectively incorporate the expectations and conflicting objectives, providing different good solutions to support decision makers.

Select this Article		Integrated Approach to Water Allocation in River Basins Mei Han, Ren Qingwang, Yi Wang, Jian Du, Zhen Hao, Fangling Sun, Li Cheng, Shanzhong Qi, and Daqiu Li Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000255 Posted ahead of print 27 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract Available water resources per capita are decreasing in river basins around the world. A wide range of techniques and models have been used to characterize, classify, and evaluate water scarcity. Others have suggested various indicators and methods that should be used to allocate water resources. This paper attempts an integrated approach to water allocation which accounts for a wide range of factors at the river basin level. Using the Hai, Huai, and Yellow River Basins of Shandong Province, 19 indicators were assimilated into a water scarcity index and weighted based on surveys collected from 82 multi‐disciplinary experts. Fuzzy set probability was then used to quantify water scarcity for each river basin. A water allocation method was also calculated using 13 indicators and objectively weighted using the analytical hierarchy process. Results show that all river basins in Shandong Province have severe water scarcity and highlight that economic factors (i.e. population density, per capital gross domestic product, cultivated land ratio, irrigation ratio, industrial output ratio, and industrial output value) play the most critical role in water scarcity, followed by water supply factors (i.e. per capita water supply, utilization ratio, groundwater supply ratio, and external supply ratio), then water demand (i.e. urban water demand, water demand per unit gross domestic product, water consumption rate, and water saving rate) and water shortage (i.e. water deficiency ratio). Water allocation indicators were prioritized according to water resource pressure and utilization proportionality among districts in the Huai River Basin. The results should prove useful for future water management initiatives and provide direction for future research.

Select this Article		Uncertainty Quantification for a Middle East Water Supply System Rachel E. Bullene, J. Paul Brooks, Edward L. Boone, Clive Lipchin, Toni P. Sorrell, and Charles R. Stewart Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000253 Posted ahead of print 27 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract In this paper, we introduce a framework for incorporating uncertainty in water supply system models that uses Bayesian statistics and mixed‐integer programming. The output of the framework includes the most‐probable least‐cost solution, the probability of feasibility for a given solution, component probabilities for each decision, and a distribution of the optimal objective function value. The method is applied to the problem of developing a water supply system design for Israel, Jordan, and the Palestinian territories. The method allows decision‐makers to evaluate various alternatives for a water supply plan that incorporates uncertainties in future demand and costs. The design of a water supply plan is a problem with properties that are distinct from traditional approaches to water distribution system (WDS) design; namely, local engineering decisions concerning pipe diameters and water pressure are not explicitly modeled, but large‐scale decisions concerning the construction of water conveyances (pipes, canals, tunnels) and sources (desalination plants) are the focus in the model.

Select this Article		Cooperation in Transboundary Water Sharing with Issue Linkage: A Game‐Theoretical Case Study in the Volta Basin Anik Bhaduri and Jens Liebe Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000252 Posted ahead of print 11 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract The paper investigates issue linkage of water and energy in transboundary water sharing agreements and evaluates how such issue linkage can enhance the scope of cooperation between upstream and downstream countries. In a case study on transboundary water sharing between Burkina Faso and Ghana, the main upstream and downstream riparians in the Volta Basin, the paper evaluates both the scope and sustainability of such cooperation based on issue linkage. In the framework of a static Stackelberg game with numerical analysis, we find that the interdependency of countries can lead to efficient and effective solutions regarding water sharing. In the cooperation phase, Ghana has the opportunity to increase its water consumption for agriculture, which is currently restricted, while Burkina Faso benefits from discounted hydropower as a compensation for restricting its water consumption. In such a case, the cooperation is mutually beneficial and stable. However, such kind of interdependency may not be sustaining in the very long run, i.e. when population increase induces Burkina Faso to increase its water consumption and destabilizes the cooperation based on the water and energy issue linkage. Overall, the results show that issue linkages within the water sector might present additional strategies to generate benefits from cooperation on transboundary rivers by taking into account more than water use alone. The collective benefits of hydropower can lead to an overall improvement in welfare.

Select this Article		A Simulation‐Optimization Approach to Design Low Impact Development for Managing Peak Flow Alterations in Urbanizing Watersheds Chandana Damodaram and Emily M. Zechman Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000251 Posted ahead of print 11 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract The process of urbanization transforms natural landscape into impervious land cover, affecting the ecosystem health of receiving water bodies and downstream communities by changing the timing and volumes of the natural flow regime. Best Management Practices (BMP) and Low Impact development (LID) are a set of mitigating measures which can be considered for watershed management to mitigate the hydrologic consequences of urbanization. This research develops a methodology to select sites for placing LID technologies, namely rainwater harvesting and permeable pavements, to reduce hydrologic impacts, measured as alterations to the peak flow, while meeting a pre‐specified budget. A simulation‐optimization methodology couples a genetic algorithm with a hydrologic model, a hydraulic model, and curve number‐based models of LID technologies. The trade‐off between costs and peak flow alteration is explored by optimizing LID placement under varying budget constraints. Strategies that combine a detention pond and LID are explored and optimized for a spectrum of design storms, including 2‐yr, 10‐yr, and 100‐yr events. Trade‐offs among management strategies that are designed to control storms of different sizes are analyzed. The simulation‐optimization framework and methodology is applied for a small watershed on the Texas A&M University campus.

Select this Article		Estimating Maximal Annual Energy Given Heterogeneous Hydropower Generating Units with Application to the Three Gorges System Fang‐Fang Li, Christine A. Shoemaker, D. M. ASCE, Jia‐Hua Wei, and Xu‐Dong Fu Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000250 Posted ahead of print 11 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract A hierarchical method for structured optimization model is presented for the assessment of potential maximum energy output of the Three Gorges Project and Gezhouba cascade hydropower stations on Yangtze River in China. The optimization is based on a detailed description of daily load dispatching among different types of hydropower units. The optimization method is divided into three levels to make computation of the global optimization problem feasible. In Levels 1 and 2, a genetic algorithm is applied to optimize discharge and water head distribution between the upstream and downstream reservoirs. Level 1 selects the water levels at the beginning of each of the months in a year. Level 2 selects the water levels at the beginning of each day in a month. Level 3 solves a linear programming problem for allocation of water among the heterogeneous types of hydropower generation. In Level 2, the model runs in parallel (with 30 processes) for daily optimization in every month. Actual operating data from 2005 are used to verify the model, and results indicate that the model can represent the actual processes with a high accuracy. Hydrological data of the year 2004 and 2005 are used to perform an optimized power generation process within the operating rules. The results indicate that the maximal annual energy production could be about 61 MWh higher than the actual in 2004 and 87 MWh higher in 2005.

Select this Article		Centralized vs. Decentralized Wastewater Reclamation in the Houghton Area of Tucson, AZ Gwendolyn J. Woods, Doosun Kang, Daniel R. Quintanar, Edward F. Curley, Stephen E. Davis, Kevin E. Lansey, and Robert G. Arnold Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000249 Posted ahead of print 3 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract Reclaimed wastewater is increasingly important to satisfaction of water sustainability objectives in water‐short municipalities throughout the United States and particularly in the Southwest. Water reclamation and reuse present new challenges for urban planners, who now tend to consider renewable fresh water and reclaimed wastewater as unique parts of a single water resources portfolio. Efficiency objectives in geographically disperse communities lead planners to explore the relative merits of centralized versus decentralized wastewater treatment capacity when new construction is required. However, the complexity of the planning landscape, in which existing water distribution and sewerage capacities; geographic factors; and uncertainty in growth projections, energy cost and even the sustainability of existing freshwater supplies contribute to plan selection, suggests that decision support methods can usefully supplement engineering judgment in order to find a near optimal level of decentralization in facilities planning. Here, an existing decision support system (DSS) was modified to include costs attributable to infrastructure construction, operation, and maintenance for wastewater collection and both potable and reclaimed water transmission at the regional (city or city subsection) level in order to aid water supply planning. The modified DSS was then applied to a study area in southeast Tucson, AZ. Several scenarios are developed and compared on the basis of cost and energy consumption. A sensitivity analysis is provided. In general, increased peripheral demand, limited existing capacity, greater elevation differences, and lower discount rates favor decentralized design and construction.

Select this Article		Bi‐Level Optimization of Regional Water Resources Allocation Problem under Fuzzy Random Environment Jiuping Xu, M. ASCE, Yan Tu, and Ziqiang Zeng Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000248 Posted ahead of print 3 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract The allocation of water resources has long been recognized as a critical optimization problem. In this study, a bi‐level programming model with fuzzy random variables is developed for tackling a regional water resources allocation problem based on water rights distribution in a river basin. The bi‐level programming model takes the optimal total benefit of the society and the optimal economic benefit of each sub‐area as the upper and lower targets respectively. In contrast to previous study, the balance of the satisfactory degree between the upper and lower decision makers is considered in the bi‐level optimization for ensuring the equity of the water resource allocation. To deal with inherent uncertainties, the fuzzy random variables are first transformed into trapezoidal fuzzy numbers, and by taking advantage of the expected value operation, the trapezoidal fuzzy numbers are subsequently defuzzified. For solving the complex and non‐linear bi‐level programming model, an interactive fuzzy programming technique and an entropy‐Boltzmann selection‐based genetic algorithm are designed as a combined solution method. Finally, the results and comparisons analysis of a case study are presented to demonstrate the practicality and efficiency of the optimization method.

Select this Article		Automated Creation of District Metered Areas Boundaries in Water Distribution Systems Kegong Diao, Yuwen Zhou, and Wolfgang Rauch Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000247 Posted ahead of print 3 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract Accounting for water in distribution system can be improved by dividing systems into smaller metered zones. This manuscript proposes an approach which could create district metered areas (DMA) boundaries automatically based on community structure of water distribution systems. Community structure, the gathering of vertices into communities such that there is a higher density of edges within communities than between them, is a common property of many complex systems. For verification, the method was tested on a real‐world distribution system and the result was compared with a manually designed DMAs layout. As the achieved community structure is in excellent agreement with the zoning plan in reality, this approach, although further improvements are necessary, is a new addition to the number of other automated methods aimed at complementing and eventually substituting the empirical trial‐and‐error approach.

Select this Article		Characterization of Public and Stakeholder Objectives in Environmental Management: A Case Study of New Hampshire's Lamprey River Shannon H. Rogers, Ph.D., John M. Halstead, Ph.D., and Thomas P. Seager, Ph.D. Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000246 Posted ahead of print 14 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract Management plans for natural resources can be seen as policy instruments that deliver multi‐attribute goods held in the public domain requiring input from experts, stakeholders, and citizens. This research adds a key dimension to the state of New Hampshire's Lamprey River Instream Flow Study. Using a series of quantitative and qualitative research methods, the values and objectives of stakeholders and the general public were analyzed regarding management of the river. Findings show that respondents are most concerned with the ecological integrity of the river above all other attributes elicited from the stakeholders (e.g. water withdrawal amount, recreation days, and number of community business users).

Select this Article		Review of Methods and Tools for Managing Losses in Water Distribution Systems Harrison E. Mutikanga, Saroj K. Sharma, and Kalanithy Vairavamoorthy Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000245 Posted ahead of print 3 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract The water industry worldwide is facing challenges of water and revenue losses. To reduce these losses and improve efficiency of water distribution systems, tools and methods have been developed over the years. This paper reviews the current tools and methodologies applied to assess, monitor and control losses in water distribution systems. The aim is to identify the tools and methods that have been applied; the knowledge gaps and future research needs.

Select this Article		Reservoir Operation for Simultaneously Meeting Water Demand and Sediment Flushing: A Stochastic Dynamic Programming Approach with Two Uncertainties Ashkan Shokri, Omid Bozorg Haddad, and Miguel A. Mariño Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000244 Posted ahead of print 3 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract River bed materials are commonly removed and conveyed downstream. In this process, some sediments are deposited in reservoirs, causing a decrease in reservoir active storage capacity and thus its ability in meeting water demand. Flushing is a sediment‐release method, operated from the bottom outlet gates, releasing stored water to flush sediments. As a result, water shortages may occur after the flushing operation. Thus, it is important to develop a reservoir operation policy for time and volume release of sediment that meets water demand. Uncertainties in water and sediment inflows to the reservoir are also important issues that add to the complexity of such policies. This paper presents a stochastic dynamic programming model with two uncertainties to determine the simultaneous optimal operation policies for meeting water demand and sediment flushing. To evaluate the capability of the SDP model with two uncertainties, four other operation policies are developed and all five scenarios are evaluated by using various performance indices in the Sefidroud reservoir of northern Iran. All scenarios are designed with different rules and priorities of water and sediment release. The best performance indices are those resulting from the optimization scenario that considers both inflow and sediment uncertainties.

Select this Article		Probabilistic Analysis and Optimization to Characterize Critical Water Distribution System Contamination Scenarios Amin Rasekh, S. M. ASCE and Kelly Brumbelow, M. ASCE Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000242 Posted ahead of print 10 March 2012 Full Text: \| Download PDF
	+ -	Show Abstract Characterization of critical water distribution system (WDS) contamination scenarios — defined by a set of attributes, a probability of occurrence, and a specific level of consequences — is a prerequisite for preparation of reliable and cost‐effective mitigation, preparedness, and emergency response plans. This study develops Monte Carlo and risk‐based optimization schemes to evaluate contamination risk of WDSs for generation of this important class of scenarios that are representative of the most vulnerable aspects of the system. Defining attributes of contamination scenarios are identified as contaminant type and amount, contamination location, start time, duration, and time of year it occurs. Well‐documented waterborne outbreaks reported in developed nations are analyzed to empirically estimate statistical characteristics of defining attributes in accidental events. Monte Carlo simulation is conducted to determine the probability distribution of public health consequences, aggregate conditional risk, and significance of different scenario attributes. A multiobjective optimization methodology is proposed to capture the attributes of critical accidental contamination scenarios. The principal risk components of likelihood and health consequences are treated as optimization objectives and are maximized simultaneously to identify an ensemble of non‐dominated critical scenarios. The multiobjective approach provides insight into system risk and potential mitigation options not available under maximum risk or maximum consequences analyses. Performance and applicability of developed models is demonstrated on WDS of a virtual mid‐size city that possesses characteristics of complex real‐world distribution networks.

Select this Article		Extension of Parametric Rule with the Hedging Rule for Managing Multi‐Reservoir System during Droughts Xuning Guo, Tiesong Hu, Xiang Zeng, and Xinjie Li Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000241 Posted ahead of print 3 March 2012 Full Text: \| Download PDF
	+ -	Show Abstract In contrast to most common methods used in optimal control of reservoir systems requiring a large number of decision variables, parametric rule can make a radical reduction of the number of decision variables without yielding inferior solutions. However, parametric rule employs the standard operating policy to determine releases of reservoirs as much as demand only if there is enough water in the system. That may result in single periods of severe short supply during droughts. The purpose of this paper is to devise an operating rule for multi‐reservoir by combining parametric rule with the hedging rule to avoid catastrophic water shortage during droughts. In this way, decision variables to be optimized not only make a significant reduction compared to traditional operating rules, but severe short supply during droughts can also be controlled effectively. This paper employs a water‐supply multi‐reservoir system in Northern China to explore the changes of shortage characteristics produced by the proposed rule over a long horizon. In the case study, particle swarm optimization (PSO) algorithms with a simulation model are used to optimize the decision variables. The results indicate that the extended parametric rule has a significant advantage over the classic parametric rule in dealing with the multi‐reservoir operation problem during droughts.

Select this Article		Multivariate Trajectory Clustering for False Positive Reduction in Online Event Detection Sean A. McKenna, Eric D. Vugrin, David B. Hart, and Robert Aumer Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000240 Posted ahead of print 3 March 2012 Full Text: \| Download PDF
	+ -	Show Abstract Online monitoring of multivariate water quality data is becoming a practical means of improving distribution network management and meeting water security goals. Changes in water quality are often due to changes in the hydraulic operations of the network. These operational changes create patterns of water quality change that are similar, but not exactly the same, from one instance to the next. Classification of multivariate change patterns through trajectory clustering is introduced here to create a pattern library from historical water quality data and as an online process with the goal of reducing false positive water quality event detections. Prior to event declaration, a short sequence of the preceding multivariate data is compared against the pattern library to assess its similarity to a previously observed pattern.¹ A fuzzy clustering algorithm is utilized to assign multivariate pattern memberships for water quality patterns associated with water quality events in both the offline and online modes of operation. The utility of trajectory clustering for multivariate pattern recognition in time‐series data is demonstrated with two example applications. The first example uses observed water quality with simulated patterns and events. The pattern matching reduces the number of false positive event detections by 91 percent relative to the case of not using the pattern matching. The same false positive event reduction is achieved when both patterns and separate water quality events are added and 100 percent event detection is achieved. The second example uses observed water quality data from a metropolitan distribution system in the United States. The pattern matching approach developed here is able to reduce the false positive event detections by 68 percent.

Select this Article		Fast Hybrid Optimisation Method for Effective Pump Scheduling Carlo Giacomello, Zoran Kapelan, and Matteo Nicolini Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000239 Posted ahead of print 3 March 2012 Full Text: \| Download PDF
	+ -	Show Abstract The cost of electricity used for pumping in water distribution systems typically represents the largest part of the total operational costs. Therefore, optimisation of pump operations is a major concern for water utilities around the world, especially in recent years with significantly increasing energy prices. Recently, in order to maximise cost and energy savings, pump scheduling is frequently done in real‐time by integrating the relevant optimisation software into the water company's Supervisory Control and Data Acquisition (SCADA) system. This, however, requires solving a complex, large, non‐linear optimisation problem in a computationally efficient manner, typically in less than one hour. To achieve this, the pump scheduling problem is solved here by a novel hybrid optimisation method LPG which makes use of Linear Programming (LP) and a Greedy Algorithm. The new methodology is applied to two case studies, the artificial, benchmark case study of Anytown network and the real‐life pump scheduling problem of the Richmond Water Distribution Network (WDN). The results obtained clearly demonstrate that the LPG hybrid method is capable of solving real‐life pump scheduling problems in a computationally extremely efficient manner whilst preserving the accuracy, i.e. the near‐optimality of the obtained solution. This makes the method particularly appealing for use in real‐time pump scheduling applications.

Select this Article		Temperature and Precipitation Trends in Lebanon's Largest River: The Litani Basin H. H. Ramadan, R. E. Beighley, and A. S. Ramamurthy Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000238 Posted ahead of print 3 March 2012 Full Text: \| Download PDF
	+ -	Show Abstract This study deals with the historical hydro‐climatological watershed characteristics of the Litani basin located in Lebanon, east of the Mediterranean Sea, during 1900–2008. The basin is divided into 2 distinct sub‐basins. The Upper Litani Basin (ULB) is mostly dominated by mountainous geophysical features and the Lower Litani Basin (LLB) is closer to the Mediterranean coast. Monthly and annual temperature and precipitation data were generated from different sources including global gridded data, satellite data and local station data. As long term runoff records were not available, previously generated monthly synthetic runoff data were employed. Temperature and precipitation trends were investigated using the Mann‐Kendall and Sen Slope nonparametric trend tests. The mean annual and monthly runoff was subsequently correlated with temperature and precipitation variations using a multiple linear regression approach. The results show that between 1900 and 2008, the whole Litani basin, including both sub‐basins, experienced a drying trend without a significant change in temperature. However, within the 1970–2008 period, the whole basin grew notably warmer in all seasons, without being wetter; this climatic pattern was reflected in the LLB but not in the ULB, which was only slightly warmer but also slightly wetter in this period. In addition, the results revealed distinctive seasonal and annual correlations between temperature and precipitation changes and the basin's runoff. However, runoff for both the ULB and the LLB was shown to be more frequently correlated with precipitation than with temperature. Positive correlations were found between runoff and precipitation during winter and wet seasons, while a negative correlation was detected during winter between temperature and runoff variations of the ULB. Hence, continuation of increasing temperature and decreasing precipitation trends may pose a threat to future water‐resources in the Litani as a whole, and the ULB in particular.

Select this Article		Water Management Decisions Using Multiple Hydrologic Models within the San Juan River Basin under Changing Climate Conditions W. Paul Miller, R. Alan Butler, Thomas Piechota, James Prairie, Katrina Grantz, and Gina DeRosa Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000237 Posted ahead of print 3 March 2012 Full Text: \| Download PDF
	+ -	Show Abstract A modified version of the Bureau of Reclamation (Reclamation) long‐term planning model, Colorado River Simulation System (CRSS), is used to evaluate whether hydrologic model choice has an impact on critical decision variables within the San Juan River Basin when evaluating potential impacts of climate change through 2099. The distributed Variable Infiltration Capacity (VIC) model and the lumped National Weather Service (NWS) River Forecast System (RFS) were each used to project future streamflow; these projections of streamflow were then used to force Reclamation's CRSS model over the San Juan River Basin. Both hydrologic models were compared to evaluate whether or not uncertainty in climatic input generated from General Circulation Models outweighed differences between the hydrologic models. Differences in methodologies employed by each hydrologic model had a significant impact on projected streamflow within the basin. Both models project decreased water availability under changing climate conditions within the San Juan River Basin, but disagree on the magnitude of the decrease. On average, total naturalized inflow within the San Juan River Basin into the Navajo Reservoir is approximately 15% higher using inflows derived using the VIC model than those inflows developed using the RFS model; average projected tributary inflow from the San Juan River Basin to the Colorado River is approximately 25% higher using inflows derived using the VIC model than those inflows developed using the RFS. Overall, there is a higher risk and magnitude of shortage within the San Juan River Basin using streamflow developed using the RFS model as compared to inflow scenarios developed using the VIC model. Model choice was found to have a significant impact on the evaluation of climate change impacts over the San Juan River Basin.

Select this Article		Scenario‐Based Robust Optimization of Regional Water/Wastewater Infrastructure Doosun Kang and Kevin Lansey Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000236 Posted ahead of print 2 February 2012 Full Text: \| Download PDF
	+ -	Show Abstract Uncertainties facing water planners and designers include changes in demand due to community growth (temporal and spatial), per‐capita water use, public perceptions, and regulations. One of the most powerful and intuitive ways to represent these uncertainties in the planning stage is to use scenarios. A scenario represents a realization of the system's random parameters. Scenario‐based analysis provides organizational flexibility by planning for multiple potential future scenarios; each of which may be, although is not necessarily, associated with a probability of occurrence. Here, we present a scenario‐based multi‐objective optimization model for robust optimal design of regional‐scale water and wastewater infrastructure. The proposed methodology is demonstrated with an application to the planning of decentralized water supply and reuse system for a new development area in metropolitan Tucson where sustainable water supply is a significant issue.

Select this Article		Economic Analysis of Leakage in the Bangkok Water Distribution System M. Shafiqul Islam and Mukand Singh Babel Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000235 Posted ahead of print 1 February 2012 Full Text: \| Download PDF
	+ -	Show Abstract Loss of water due to leakage is a common phenomenon observed in all water distribution systems (WDS). The volume of leakage around the world is considerably high and its control is crucial to meet the increasing water demand caused by rapid population growth and urbanization. The most important component of a leakage control strategy is target setting in terms of economic level of leakage (ELL). The ELL is an economic indication depending on individual network conditions, operating system pressures, demands and their patterns, marginal cost of water, and operating practices. This paper discusses the economic aspects of leakage for a pilot district metered area (DMA) of the WDS of Metropolitan Waterworks Authority (MWA) in Bangkok, Thailand. The study developed two nomographs for the quick estimation of ELL and active leakage control cost (ALC) with minimal data analysis. The first nomograph shows the relationship between cost of leakage control, average operating pressure, and level of leakage in the WDS. The second nomograph shows the relationship between ELL, operating system pressure, and marginal cost of water. The nomographs have been developed based on leakage volume, cost of water, and hydraulic and operational conditions of the WDS. To model different hydraulic and leakage scenarios, the EPANET simulation engine has been used. The research will help utility managers understand different aspects of the leakage economics and will lead to a better management of their WDS.

Select this Article		Short‐Term Real‐Time Reservoir Operation for Irrigation A. Srinivasa Prasad, N. V. Umamahesh, and G. K. Viswanath Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000234 Posted ahead of print 1 February 2012 Full Text: \| Download PDF
	+ -	Show Abstract The development and management of irrigation facilities has been recognized as the key to national development in India. Despite high priority and massive investments, the performance of major irrigation projects has been disappointing. Substantial benefits can be achieved from relatively small increase in operating efficiencies. The main objective of the study is to develop a short‐term real‐time reservoir operating policy in multi‐crop, multi‐season environment integrating reservoir release decisions with the field irrigation requirement. Real‐time reservoir operation model defines the set of releases to be made into each off take on main canals of reservoir for the known set of release targets, reservoir storage state and forecasted inflow in the current period, minimizing the deficit function. Inter‐crop allocation model allocates reservoir release of the current period among competing crops. On implementing the irrigation decisions of the inter‐crop allocation model for the current period, soil moisture is updated with the actual rainfall occurred and irrigation applied in the current period. A new set of irrigation targets for the remaining periods is determined by running the single crop intraseasonal allocation model for each crop constraining the allocations of the previous periods to the actual irrigation made. With the revised targets and updated reservoir storage, reservoir operation and inter‐crop allocation models are run sequentially for all time periods in real‐time. The models developed are demonstrated through a case study of Nagarjuna Sagar Reservoir Project. Real‐time reservoir operation model is run for the year 2004–2005 data with and without updating irrigation targets and the results are discussed. Crop production measure is found to be high in case of updated targets emphasizing the importance of updating irrigation targets.

Select this Article		Optimal Watershed Management for Reservoir Sustainability: An Economic Appraisal Yoon Lee, Taeyeon Yoon, and Farhed A. Shah Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000232 Posted ahead of print 1 February 2012 Full Text: \| Download PDF
	+ -	Show Abstract Accumulation of sediment from upstream agricultural land may shorten the lifetime of a reservoir and reduce its long‐term benefits. This paper presents a framework for assessment of management strategies which simultaneously considers upstream soil conservation and downstream reservoir‐level sediment control. A dynamic model that utilizes optimal control theory is developed for this purpose. Simulation results from the model are expected to provide practical information for policy‐makers, such as determination of the best sediment removal technology, the optimal timing to install this technology, and the optimal pattern of soil conservation efforts. An illustrative application to Lake Aswan, which is located between the Sudan and Egypt, indicates that the highest permissible level of soil conservation and the unconstrained dredging installed at 22 years are the best management practices, giving a sustainable life of the reservoir and net benefits of $117.8 billion. The cooperative strategy compared to the non‐cooperative and base‐line strategies, increases social net benefits by $6.5 billion and $7.8 billion, respectively. To test the robustness of our results, we perform sensitive analysis for key parameters, such as interest rate, water price, agricultural sediment contribution, and soil conservation effectiveness. The results are very sensitive to selected parameters. As suspected, interest rate and water price shift the net present value of watershed both side. However, the rank of alternatives does not change.

Select this Article		Optimal Design of Groundwater‐Quality Sampling‐Networks with 3D Selection of Sampling Locations Using an Ensemble Smoother Graciela S. Herrera and Roel Simuta‐Champo Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000230 Posted ahead of print 16 January 2012 Full Text: \| Download PDF
	+ -	Show Abstract In groundwater quality monitoring it is important to consider that groundwater contaminant concentration can vary vertically. In order to find the actual concentration of contaminants in a groundwater plume, it may be necessary to sample at different depths at the same location. This can be expensive due to the initial cost of the wells and to the costs of multiple chemical analyses for each round of sampling. A sampling optimal design in three dimensions allows identifying the contaminant‐concentration variations in all spatial directions at a minimum cost. The objective of this paper is to extend a methodology for the optimal design of groundwater quality sampling networks proposed by Herrera (1998), to include the selection of measurements at different depths. The method is based on the application of an ensemble smoother, a stochastic transport model and a sequential optimization method. The method is demonstrated for the design of 3D groundwater monitoring networks in two hypothetical problems.

Select this Article		A Box‐Constrained Optimization Methodology and Its Application for a Water Supply System Model Mashor Housh, Avi Ostfeld, M. ASCE, and Uri Shamir, F. ASCE Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000229 Posted ahead of print 12 January 2012 Full Text: \| Download PDF
	+ -	Show Abstract This study introduces a new search method for box‐constrained optimization problems entitled Search Method for Box Optimization (SMBO). SMBO is a population heuristic based search methodology which solves global optimization problems. SMBO represents the population as Probability Density Function (PDF) inside the problem bounds. The PDF shape is dynamically adapted during the process to guide to a “good” search domain. The applicability and the efficiency of the method are demonstrated using two benchmark sets, which include unimodal, multi‐modal, expanded and hybrid composition functions. The performance of SMBO is compared with several genetic algorithms (GAs); the first benchmark compares it with nine codes of traditional/classic GAs, and the second compares SMBO with two recent variants of genetic algorithms. The results show that SMBO performs as well as or better than the GAs in both comparisons. The method is demonstrated on a nonlinear model for management of a Water Supply System (WSS), and the results are compared to the commercial GA toolbox of MATLAB.

Select this Article		A Proposed Smart Market Design for Sediment Discharge Antonio A. Pinto, John F. Raffensperger, Thomas A. Cochrane, and E. Grant Read Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000228 Posted ahead of print 7 January 2012 Full Text: \| Download PDF
	+ -	Show Abstract Sediment discharge from erosion, urban run‐off, and construction can cause environmental degradation. Governments try to regulate sediment, but the regulatory approach is costly to land owners. In principle, a market‐based system could reduce costs, but the associated transaction costs are far too high, as market participants must find trading partners, negotiate, and seek government approval. In this paper, we propose a smart market design with an associated market clearing model for sediment discharge. Market participants bid for and offer tradable discharge allowances to a central auctioneer. The allowances correspond to kilograms of sediment discharge per year, as estimated by an erosion model. The auctioneer then uses a linear program to price and allocate sediment allowances in a given catchment. Participants do not trade bilaterally, but rather through a central pool, reducing transaction costs. The market design can use all available relevant hydrological data, quantifies environmental effects explicitly, and gives price signals based on the environmental features. Additionally, the initial rights could be scaled back or up when catchment is over or under‐allocated to keep a market operator with revenue neutrality. We simulate the smart market for two catchments in Auckland, New Zealand.

Select this Article		Iterative Methodology of Pressure‐Dependent Demand Based on EPANET for Pressure‐Deficient Water Distribution Analysis Jun Liu and Guoping Yu Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000227 Posted ahead of print 7 January 2012 Full Text: \| Download PDF
	+ -	Show Abstract Traditional water distribution simulations which are referred to as demand‐driven analysis (DDA) are normally analyzed under the assumption that nodal demands are known and satisfied. The DDA is valid under normal conditions and in design requirement. However, in many situations such as pipe burst or pump outage, the outflows at nodes affected by low pressures will decrease. Therefore, network simulation under deficient pressure conditions using conventional DDA can cause large deviation from actual situations. The purpose of this paper is to analyze different composition of nodal outflow including volume driven demand, pressure‐dependent demand and leakage to simulate deficient‐network performance more realistically. An extension of EPANET which implements repetitive modifications to nodal outflows based on pressure‐dependent demand formulations and leakage model (EPANET‐MNO) is first developed. Then, a comparison is made between the respective performances of four different pressure‐dependent demand functions with the designated required pressure and minimum service pressure. The EPANET‐MNO was verified in two abnormal situations including fire flow and pipe failure isolation in steady simulation. At last, pipe failure isolation in extended period simulation was carried out on a real network. The paper demonstrates that good modeling performance and convergence of the EPANET‐MNO can be achieved for simulating deficient‐network considering volume driven demand, pressure‐dependent demand and leakage.

Select this Article		Steady‐State Behavior of Large Water Distribution Systems: The Algebraic Multigrid Method for the Fast Solution of the Linear Step A. C. Zecchin, P. Thum, A. R. Simpson, and C. Tischendorf Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000226 Posted ahead of print 7 January 2012 Full Text: \| Download PDF
	+ -	Show Abstract The Newton‐based global gradient algorithm (GGA) (also known as the Todini and Pilati method) is a widely used method for computing the steady‐state solution of the hydraulic variables within a water distribution system (WDS). The Newton‐based computation involves solving a linear system of equations arising from the Jacobian of the WDS equations. This step is the most computationally expensive process within the GGA, particularly for large networks involving up to O(10⁵) variables. An increasingly popular solver for large linear systems of the M‐matrix class is the algebraic multigrid (AMG) method, a hierarchical‐based method that uses a sequence of smaller dimensional systems to approximate the original system. This paper studies the application of AMG to the steady‐state solution of WDSs through its incorporation as the linear solver within the GGA. The form of the Jacobian within the GGA is proved to be an M‐matrix (under specific criteria on the pipe resistance functions), and thus able to be solved using AMG. A new interpretation of the Jacobian from the GGA is derived enabling physically based interpretations of AMG's automatically created hierarchy. Finally, extensive numerical studies are undertaken where it is seen that AMG outperforms the sparse Cholesky method with node reordering (the solver used in EPANET2), incomplete LU factorization (ILU) and PARDISO, which are standard iterative and direct sparse linear solvers.

Select this Article		Residential Water Conservation in Australia and California Ryan Cahill and Jay Lund Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000225 Posted ahead of print 2 January 2012 Full Text: \| Download PDF
	+ -	Show Abstract In much of the Western United States, reducing residential water use is a major source of water conservation, especially as population growth urbanizes agricultural land. While estimates of the potential of conservation are useful, the experience of Australia provides a realistic target for residential water conservation. Although reliability of urban water use data is often questionable, it is clear that Australians use less water than Californians, with a similar climate, economy, and culture. Per‐capita usage is compared, and explanations for use differences are offered. If California had the same residential water use rates as Australia, it could have reduced gross urban water use by 2,600 GL (2.1 million acre‐feet) in 2009 and potentially saved 1,800 GL (1.5 million acre‐feet) for consumptive use by others.

Select this Article		Simple Optimization Method to Determine Best Management Practices to Reduce Phosphorus Loading in Echo Reservoir, Utah Omar Alminagorta, Bereket Tesfatsion, David Rosenberg, and Bethany Neilson Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000224 Posted ahead of print 2 January 2012 Full Text: \| Download PDF
	+ -	Show Abstract This study develops and applies a simple linear optimization program to identify cost effective Best Management Practices (BMPs) to reduce phosphorus loading to Echo Reservoir, Utah. The optimization program tests the feasibility of proposed Total Maximum Daily Load (TMDL) allocations based on potential BMP options and provides information regarding the spatial redistribution of loads among sub‐watersheds. The current version of the TMDL for Echo reservoir allocates phosphorus loads to existing non‐point phosphorus sources in different sub‐watersheds to meet a specified total load. Optimization results show that it is feasible to implement BMPs for non‐point sources in each sub‐watershed to meet reduction targets at a cost of $1.0 million. However, relaxing these targets can achieve the overall target at lower cost. The optimization program and results provide a simple tool to test the feasibility of proposed TMDL allocations based on potential BMP options and can also recommend spatial redistributions of loads among sub‐watersheds to lower costs.

Select this Article		Principal Factors Analysis for Forecasting Diurnal Water Demand Pattern Using Combined Rough Set and Fuzzy Clustering Technique Jing‐qing Liu, Wei‐ping Cheng, and Tu‐qiao Zhang Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000223 Posted ahead of print 2 January 2012 Full Text: \| Download PDF
	+ -	Show Abstract The true principal factors for diurnal water demand pattern of urban water are often difficult to identify using traditional rough set algorithms since the demand pattern is usually affected by many factors which are uncertain and hard to quantify. An improved Attributes reduction algorithm based on the cumulative weighting coefficient was proposed to solve this problem. The weighting coefficient was determined by the result of variable precision rough set algorithm. To discuss the consecutive curves with mathematic tools, an improved fuzzy c‐mean algorithm (FCM) was proposed to discretize the diurnal water demand pattern in spatial. The proposed algorithms were then used to analyze the principal factors of diurnal water demand pattern in the city of Hangzhou, China. The results show that the improved Attributes reduction algorithm is capable of distinguishing the “fake” attribute from the dynamic reduction sets and fuzzy c‐mean algorithm is an effective and feasible method of solving the cluster problem for the consecutive curves. The principal factors affecting diurnal water demand pattern in Hangzhou are “maximum air temperature”, “minimum air temperature”, and “weekday or weekend”.

Select this Article		Exploring the Water‐Thermoelectric Power Nexus Vincent C. Tidwell, Peter H. Kobos, Len A. Malczynski, Geoff Klise, and Cesar R. Castillo Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000222 Posted ahead of print 21 December 2011 Full Text: \| Download PDF
	+ -	Show Abstract In 2005 thermoelectric power accounted for 41% of all freshwater withdrawals and roughly 3% of all consumptive use in the United States. With the demand for electricity projected to increase by 24% by 2035 concerns have been raised as to the availability of water for this growing industry; particularly, as the siting of several new thermoelectric facilities have been challenged on the basis of water supply. To address this concern we estimate the potential impact of water availability on future expansion of the thermoelectric power industry. Specifically, both the extent and location of thermoelectric development at risk due to limited fresh water supply is estimated for a variety of alternative energy futures that differ according to the assumed mix of fuels utilized in new plant construction. According to the analyzed scenarios water consumption for thermoelectric power generation is projected to increase by 36‐43% between 1995 and 2035, with much of this development expected to occur in basins with rapidly growing demands in the non‐thermoelectric sectors. To identify where this thermoelectric development might be problematic, projected future thermoelectric production has been mapped onto basins subject to limited water availability. For purposes of this study, water availability is defined as a local ratio of water demand to physical water supply. Results suggest that 10‐19% of all new thermoelectric power production is likely to be sited in watersheds with limited surface and/or groundwater availability. These problematic watersheds are largely located in the West.

Select this Article		Bayesian Update Method for Contaminant Source Characterization in Water Distribution Systems Hui Wang and Kenneth W. Harrison Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000221 Posted ahead of print 21 December 2011 Full Text: \| Download PDF
	+ -	Show Abstract Bayesian analysis has application to probabilistic source characterization in water distribution systems. A new implementation of Markov Chain Monte Carlo (MCMC) for this problem is described. The solution addresses the discrete nature of water distribution networks that precludes the application of MCMC methods of general applicability that have been reported elsewhere in the water resources literature. The method is applied to a hypothetical network that has been used by others to test source identification methods. The likelihood function, a key component of Bayes. rule, is evaluated using a Monte Carlo‐based stochastic water demand model. The results reinforce the need to address the multiple sources of uncertainty in the source characterization, including the stochastic variation of water demand. Further research is needed to make the approach feasible in operational environments. Limitations of the approach and future research directions are discussed.

Select this Article		Field Studies and Modeling Exploring Mean and Maximum Water Age Association to Water Quality in a Drinking Water Distribution Network John Machell and Joby Boxall Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000220 Posted ahead of print 21 December 2011 Full Text: \| Download PDF
	+ -	Show Abstract This paper presents the findings of an investigation into predicted / modeled water age and the associated quality characteristics within a UK drinking water distribution network to determine if there was a discernable link. Aquis (7‐Technologies A/S, Denmark) hydraulic and water quality software were used to identify water volumes of different ages, generated by localized demand patterns in pipes in close proximity to one another. The pipe network studied was small spatially, of a single material, having a consistent demand due to serving predominately light industry, but with interesting hydraulic patterns involving loops and mixing of water volumes, and some long retention times. Field work was undertaken to obtain water quality samples from five network locations identified as containing a broad range of calculated water age. The samples were analyzed for standard regulated parameters by a UKAS (NAMAS) accredited water laboratory in line with UK water industry standard quality assurance practice. The water sample analytical results were examined to see how a number of physical, chemical and bacteriological parameters related to the calculated water age at each sample point, heterotrophic plate counts being used as the indicator of general bacteriological water quality. Limited association between the calculated water mean age and quality parameters was observed. Further investigations, taking into account mixing of different aged water volumes and the maximum age contributions to the mean age at each sample location, produced some association. The work demonstrated that mean age is not a sufficient guide to general water quality in this small network area. Mixing effects, and maximum age volume contributions, need to be taken into account if a more comprehensive understanding of water quality is to be obtained.

Select this Article		Optimization of Well Field Operation: Case Study Søndersø Waterworks, Denmark Annette K. Hansen, Henrik Madsen, Peter Bauer‐Gottwein, Dan Rosbjerg, and Anne Katrine V. Falk Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000219 Posted ahead of print 2 December 2011 Full Text: \| Download PDF
	+ -	Show Abstract An integrated hydrological well field model (WELLNES), which predicts the water level and energy consumption in the production wells of a waterworks is used to optimize the management of a waterworks with the speed of the pumps as decision variables. The two‐objective optimization problem of minimizing the risk of contamination from a nearby contaminated site and minimizing the energy consumption of the waterworks is solved by genetic algorithms. In comparison with the historical values large improvements in both objectives can be obtained. If the existing on/off pumps are changed to new variable speed pumps, it is possible to save 42% of the specific pumping energy consumption and at the same time improve the risk objective function. The payback period of investing in new variable speed pumps is only 3.1 year, due to the large savings in electrical energy. The case study illustrates the efficiency and applicability of the developed modelling framework.

Select this Article		Short‐Term Reservoir Storage Frequency Relationships Ralph A. Wurbs, P.E., F. ASCE, Spencer T. Schnier, S. M. ASCE, and Hector E. Olmos, M. ASCE, P.E. Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000218 Posted ahead of print 2 December 2011 Full Text: \| Download PDF
	+ -	Show Abstract The water rights analysis package (WRAP) is a generalized river/reservoir system simulation model that is routinely applied in Texas in regional and statewide planning studies and administration of the water right permit system. The WRAP modeling system was recently expanded by adding short‐term storage frequency and supply reliability analysis capabilities. Individual reservoirs and multiple‐reservoir systems can be analyzed considering numerous water users and complex water management practices. The new modeling features are based on dividing the hydrologic period‐of‐analysis into many short simulation sequences with each starting with the same storage conditions. Two alternative frequency/reliability analysis methodologies, called the equal‐weight and probability array options, are compared in the paper with a case study application. The probability array option is designed to improve the accuracy of storage frequency estimates by modeling hydrologic persistence as reflected in preceding reservoir storage contents based on a regression of natural streamflow versus preceding storage from a long‐term simulation.

Select this Article		A New Integrated Condition Assessment Model for Combined Storm Sewer Systems Ilham Ennaouri, M.ScA and Musandji Fuamba, P. Eng., Ph.D. Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000217 Posted ahead of print 2 December 2011 Full Text: \| Download PDF
	+ -	Show Abstract Optimal assessment of the overall state of the degradation affecting sewer systems requires consideration of both the hydraulic and the structural aspects. The authors identify a set of 15 factors — pertaining to both degradation aspects — as primary and constituting the framework for hierarchical structuring of the condition states. The relative importance of these factors was determined by the analytic hierarchy process (AHP). The proposed model was successfully applied to assess the current degradation state of the sewer network in Saint‐Hyacinthe, Quebec. The relative significance effect, assessing prevalence of either the hydraulic or the structural criteria in the degradation process, was established through sensitivity analysis. The outcome indicates that hydraulic factors have to be integrated in the pipe deterioration model as well as the structural ones. With a reference case set at ws = 0.5 (i.e. structural and hydraulic criteria having the same significance level), results remained conservative most of the time. Even if the AHP technique was already applied in sewers and water mains as shown in the literature, this paper is unique in that the AHP technique is used to combine a large number (fifteen) of structural and hydraulic criteria and sub‐criteria. The proposed model will enable researchers and municipal engineers to weigh the structural criterion against the hydraulic one as to achieve adequate intervention, carefully planned through a flexible tool outlaying a hierarchy of scores reflecting the infrastructure under consideration.

Select this Article		Representing Energy Price Variability in Long‐ and Medium‐Term Hydropower Optimization Marcelo A. Olivares and Jay R. Lund Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000214 Posted ahead of print 24 November 2011 Full Text: \| Download PDF
	+ -	Show Abstract Representing peak and off‐peak energy prices is often difficult in hydropower modeling because the time scale of price variability (hours or less) is much shorter than that needed for many operations planning models (days to months). This work extends and examines the reliability of an existing approximate method to incorporate hourly energy price information into revenue functions used in hydropower reservoir optimization models with larger time steps (weekly, monthly, etc). The method assumes constant head, an exogenously known frequency distribution for hourly prices during each modeled time period (day, week, month) and a revenue‐maximizing operational strategy that allocates hydropower releases in order of decreasing hourly price. The method is extended to the case with minimum instream flows requirements. The reliability of the method was tested for the cases with and without minimum instream flow requirements. Revenue estimates for a hypothetical hydropower site were compared with the exact optimal revenue from solving the hourly optimization problem within one week, showing less than 1% error using a finely discretized price frequency curve.

Select this Article		Finding Least‐Cost Pump Schedules for Reservoir Filling with a Variable Speed Pump József Gergely Bene and Csaba János Hős Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000213 Posted ahead of print 9 November 2011 Full Text: \| Download PDF
	+ -	Show Abstract This paper presents a simple and straightforward technique to solve the problem of least‐cost reservoir filling with the help of a variable speed pump in the case of a highly simplified hydraulic system. Although artificial performance curves are used, the presented technique is directly applicable for real‐life hydraulic systems of the same topology. The technique is based on keeping the specific energy consumption of the pump as low as possible and uses easy‐to‐implement control policy. Due to the simplicity of the model, the authors believe that it can serve as a tutorial or benchmark problem for pump schedule optimization problems. The near‐optimality of the results is demonstrated numerically by comparing them to the solution of a general‐purpose global optimization software.

Select this Article		Seasonal Water Allocation — Dealing with Hydrologic Variability in the Context of Water Rights System Hang Zheng, Zhongjing Wang, Siyi Hu, and Hector Malano Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000210 Posted ahead of print 8 November 2011 Full Text: \| Download PDF
	+ -	Show Abstract In China water rights allocation in river basins are customarily determined by annual mean volumes of water resources. However, seasonal variability of water availability should be considered for an effective and flexible allocation policy. This paper summarizes a framework for seasonal water allocation. It proposes a modified rule for seasonal water allocation based on the traditional rule used in China and introduces a risk analysis model to assess the performance improvement of the proposed rule when dealing with hydrologic variability in the context of a water rights system. The framework and models were applied to the Shiyang River Basin, Gansu Province, China, and they indicated that seasonally allocated water under the modified rule is more stable and has lower risk for water use than a rule based on annual mean volumes. This leads to more reliable supplies over the seasons and could provide an effective method for water rights operation in the Shiyang River Basin. It also presents a useful reference for water resource management in other water‐deficient regions of China.

Select this Article		Extreme Impact Contamination Events Sampling for Real Sized Water Distribution Systems Lina Perelman and Avi Ostfeld, M. ASCE Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000206 Posted ahead of print 20 October 2011 Full Text: \| Download PDF
	+ -	Show Abstract Contamination warning systems are being designed to protect water distribution systems against deliberate contamination intrusions. To design a contamination warning system contamination intrusion events need to be selected. Since contamination intrusions are random, even for a medium‐size network the theoretical number of possible injection events is huge, and thus the number of contamination events which can be considered in the design process is limited. To effectively cope with the threat of contamination events there is a need to identify those critical instances. A straightforward approach of enumerating all possible contamination intrusions from which critical events can be selected is limited to small systems. As critical events are rare the probability of revealing them using common Monte Carlo randomized simulations is very small or requires an extensive impractical computational amount of trials. In this study a methodology utilizing importance sampling (IS) and cross entropy (CE) based on a recent published work of the authors is further tested on real sized water distribution systems of increasing complexity. The results demonstrate the robustness of the methodology in terms of improved run times suggesting computational feasibility for problems whose size prevents full enumeration or application of direct MC simulation techniques.

Select this Article		The Role of Modeling Uncertainty in the Estimation of Climate and Socio — Economic Impact on River Water Quality Gabriele Freni, Giorgio Mannina, and Gaspare Viviani Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000208 Posted ahead of print 20 October 2011 Full Text: \| Download PDF
	+ -	Show Abstract Climate is one of the most important factors leading to changes in the hydrologic and environmental characteristics of river basins. When considering water quality, the natural factors should be weighed against anthropogenic factors (such as urbanization, increased population, and higher water demand) that may increase or decrease the effect of climatic modifications. Any prediction of future climatic and anthropogenic scenarios is affected by uncertainty as well as the modelling tools that are used for evaluating their impact on receiving water bodies. The present paper is aimed at investigating the complexity of such analyses and the uncertainty related to future impact predictions based on limited databases. Specifically, the study is focused on quantifying the impact of urbanization and social changes coupled with climate on river water quality under uncertainty. The study was carried out at a small catchment scale (less than 100 km²), an analysis that has been lacking from the field so far. The analysis took into account both anthropogenic change and climate determined from observed data. Due to inherent uncertainty in the model caused by the complexity of the model and its calibration, the analysis was performed considering the effect of such uncertainty on reliability by means of Monte Carlo simulations. This analysis has been applied to a monitored semi‐urbanized basin in Sicily (Italy). The study showed that the proposed analyses can useful for planners and urban managers; however, the uncertainty connected with mathematical modelling and small available databases has to be taken into account because it can affect decision making. The impacts of anthropogenic changes and climate can interact, thus requiring that such factors be jointly analysed. A larger effort in monitoring and characterization of natural and urban water systems is needed in order to increase the reliability of models and to improve the effectiveness of decision making based on such models.

Select this Article		Impact of Data Collection on Estimation of Wall Reaction Coefficients for Water Distribution Models M. F. K. Pasha and K. Lansey Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000207 Posted ahead of print 20 October 2011 Full Text: \| Download PDF
	+ -	Show Abstract During a model calibration process, errors in field measurements propagate to uncertainties in model parameter estimates and model predictions. This paper presents a means to quantify that effect in a water distribution water quality model and provide guidance on data collection experiment design. Water quality in the distribution systems is dominated by advective transport that is hydraulically driven. It is assumed that the hydraulic model including the nodal demand is well calibrated and provides no uncertainty. Thus, only the wall decay coefficients are to be estimated and evaluated. The uncertainty assessment procedure consists of a parameter estimation model, parameter estimation uncertainty analysis and model prediction uncertainty analysis. The shuffled frog leaping algorithm (SFLA), an optimization algorithm, is used to estimate the parameters in the water quality model in a least squares regression given a set of field data. The parameter uncertainty is calculated by a first order approximation and is further propagated to model prediction uncertainty. The model prediction uncertainty is calculated by a similar first order analysis. The methodology is applied to two networks. Alternative conditions are analyzed in terms of data collection and model prediction conditions to examine the benefits of performing pulse injection test and data collection design. Results show that pulse injection provides more information and better parameter estimates. As a result, parameters estimated from a data set with pulse injection produce lower model prediction uncertainty. For a given simulation time, earlier pulse remains in the system a longer duration providing more calibration information and hence improves the parameter estimation accuracy.

Select this Article		Improved Dynamic Programming for Reservoir Operation Optimization with a Concave Objective Function Tongtiegang Zhao, Ximing Cai, Xiaohui Lei, and Hao Wang Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000205 Posted ahead of print 15 October 2011 Full Text: \| Download PDF
	+ -	Show Abstract Diminishing marginal utility is an important characteristic of water resources systems. With the assumption of diminishing marginal utility (i.e., concavity) of reservoir utility functions, this paper derives a monotonic relationship between reservoir storage and optimal release decision under both deterministic and stochastic conditions, and proposes an algorithm to improve the computational efficiency of both deterministic dynamic programming (DP) and stochastic dynamic programming (SDP) for reservoir operation with concave objective functions. The results from a real‐world case study show that the improved DP and SDP exhibit higher computational efficiency than conventional DP and SDP: the computation complexity of the improved DP and SDP is O(n) (order of n, the number of state discretization) compared to O(n²) with conventional DP and SDP.

Select this Article		The Effect of the Seasonal Rainfall Distribution on Storm‐Water Quality Capture Volume Estimation Daeryong Park, Young‐Il Song, and Larry A. Roesner, P.E., F. ASCE Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000204 Posted ahead of print 15 October 2011 Full Text: \| Download PDF
	+ -	Show Abstract The water quality capture volume (WQCV) is a design parameter that is used for sizing urban storm‐water treatment facilities. The storage, treatment, overflow and runoff model (STORM) in NetSTORM was used to translate historical hourly rainfall records into storm event runoff data and compute the WQCV (set at the 85^th percentile capture of the annual runoff volume) of eight cities located in various climatological areas of South Korea. For each city, one‐ and two‐parameter exponential distributions were fitted to the set of storm event runoff values that were computed by STORM, and the 85^th percentile runoff depth that was determined from the STORM was compared to the 85^th percentile runoff events that were obtained from the two exponential distributions. The results demonstrate that the more easily applied distribution approach is adequate in South Korea for determining the WQCV. In Seoul, which is a city located in the northwestern part of South Korea, the two‐parameter exponential distribution yielded the best estimate of the WQCV computed by STORM. For Chuncheon, Wonju, and Daejeon, which are cities located in the north‐central part and center of South Korea, the WQCVs were accurately estimated using both the one‐ and two‐parameter exponential distributions. Finally, in the cities of Gangneung, Gwangju, Daegu, and Busan, which are located in the northeastern and southern parts of South Korea, the WQCVs were best estimated using the one‐parameter exponential distribution. It was found that seasonal variations in rainfall and rainfall event‐depth are important factors in assessing the WQCV. This study also found that the one‐parameter exponential distribution approach, which is the most common approach used in the U.S., may not be adequate for WQCV estimation if the standard deviation for average monthly rainfall is significant.

Select this Article		Water Contamination Impact Evaluation and Source‐Area Isolation Using Decision Trees Demetrios G. Eliades, S. M. ASCE and Marios M. Polycarpou, F.IEEE Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000203 Posted ahead of print 10 October 2011 Full Text: \| Download PDF
	+ -	Show Abstract The security of drinking water distribution operation is an important issue that has received increased interest within the last few years. The US Environmental Protection Agency (EPA) has issued guidelines for water utilities regarding which qualitative and quantitative metrics to monitor, as well as what response actions to take from the moment a contamination event alarm has been triggered, until the contamination has been accommodated and the system has returned to normal operation. Expanded sampling is a type of response action, in which the water utilities examine the water quality at certain locations in the network after a contamination event has been detected, to help evaluate the contamination impact and locate the source‐area. In this work, we propose a computational approach, based on decision trees, for choosing a sequence of nodes in the distribution network to perform expanded sampling, so that the water contamination impact is evaluated and the source‐area is isolated, with as few manual quality samplings as possible. To illustrate the solution methodology, we present results based on a simplified and a benchmark water distribution system.

Select this Article		Agriculture Vulnerability to Climate Change in a Snowmelt Driven Basin in Semiarid Chile Sebastian Vicuña, James McPhee, and René D. Garreaud Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000202 Posted ahead of print 8 October 2011 Full Text: \| Download PDF
	+ -	Show Abstract The Limari River basin is one of the most important watersheds in north‐central Chile (30°S). Its headwaters lie at the top of the subtropical Andes (>5000 m above sea level) and the river flows westward into the Pacific Ocean over a length of ∼200 km. This basin has a marked snowmelt driven hydrological regime and, in spite of the arid conditions that characterize this region, holds more than 50.000 Ha of highly productive agricultural land thanks to its irrigation infrastructure and three interconnected reservoirs. Like many semiarid regions around the world, north‐central Chile is expected to become warmer and drier during the 21st century as a consequence of ongoing anthropogenic climate change. The associated reduction in streamflow, changes in hydrograph timing and enhanced evapotranspiration will undoubtedly threaten agriculture in the Limarí basin and elsewhere in semiarid Chile. In this work we investigate how changes in temperature and precipitation affect surface hydrology, performance of water infrastructure and irrigation coverage in the Limari basin, using the Water Evaluation and Planning (WEAP) model. WEAP was calibrated using current climate and agriculture patterns, and then forced with a set of 30‐year long climate scenarios, each of them obtained by adding a temperature and precipitation perturbation to the historical time series. This delta‐approach allows us to (i) determine the sensitivity of selected variables to climate change, and (ii) obtain a projection of the impacts in irrigation coverage expected for the near‐ and far‐future (2010–2040 and 2070–2100, respectively). Both aspects are investigated for agricultural districts with varying access to irrigation infrastructure and groundwater; this exercise highlights the relevance of added storage and innovative conjunctive use of surface and groundwater resources for improving the resilience and adaptability of irrigated agriculture in the face of a changing climate.

Select this Article		Impact of Water Demand Parameters on the Reliability of Municipal Storage Tanks Jakobus E van Zyl, M.ASCE, Yves le Gat, Olivier Piller, and Thomas M. Walski, FASCE Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000200 Posted ahead of print 8 October 2011 Full Text: \| Download PDF
	+ -	Show Abstract Municipal storage tanks are normally sized according to inherently conservative design guidelines. An alternative way to determine the required size of a tank, based on a stochastic analysis of the system, was proposed by Van Zyl et al (2008). They recommended that tanks are sized for a minimum reliability of one failure in ten years at the most critical time of the year, typically being under seasonal peak demand conditions. In this study the same method is used to investigate the impact of different user demand parameters on tank reliability. It was found that the supply ratio, defined as the source capacity over the average demand in the week considered, is the most important demand‐related factor affecting tank reliability. It is shown that the reliability of tanks varies greatly through the year, and it is recommended that municipalities do everything possible to ensure that their system runs smoothly over the seasonal peak demand period. Several other important demand factors affecting tank reliability are also identified. It is concluded that the optimal combination of source capacity and tank size should be determined based on economical factors, and that it is likely to be system specific.

Select this Article		A Decentralized Optimization Method for Water Allocation Management in the Yellow River Basin Yi‐Chen E. Yang, Jianshi Zhao, and Ximing Cai Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000199 Posted ahead of print 26 September 2011 Full Text: \| Download PDF
	+ -	Show Abstract The management of large river basins, such as the Yellow River Basin (YRB) in China, is complicated by distributed, localized decision processes, as well as mechanisms that coordinate local decisions and manage basin‐level issues. Since 1998, the Yellow River Conservancy Commission (YRCC) has launched the Unified Water Flow Regulation (UWFR) as a centralized controlling mechanism that enforces an upper limit on water withdrawals (water use permits) for eight provinces located in the basin. The implementation of UWFR has maintained a prescribed minimum flow in the downstream channel and avoided the flow cutoff events that occurred every year between 1972 and 1998. This study attempts to explore the socioeconomic and environmental consequences of the regulation and test plans to improve water allocation management in the YRB. A decentralized optimization is combined with a multi‐agent system (MAS) framework for the YRB, in which water users, reservoirs and downstream ecological zones are defined as agents. This method iteratively determines water prices for each water use agent in the context of water market. The proposed water market scenario shows possible improvements of the UWFR with respect to social, economic and environmental objectives.

Select this Article		Calibration of Proportional Controllers for the RTC of Pressures to Reduce Leakage in Water Distribution Networks A. Campisano, C. Modica, and L. Vetrano Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000197 Posted ahead of print 26 September 2011 Full Text: \| Download PDF
	+ -	Show Abstract Pressure control is a key issue for the reduction of water loss via leakage in municipal water distribution networks (WDNs). The paper presents a general method to calibrate the proportional controllers for the real time control (RTC) of motorized pressure valves in WDNs in order to reduce leakage during ordinary operation. The method is based on the comprehensive dimensionless analysis of the behaviour of simplified hydraulic systems under RTC scenarios. A numerical approach was used to derive a simple regressive relationship to tune the controller on the basis of the system dimensionless variables involved in the control process. The method was validated by application to a well known bench‐test water distribution network and compared with an existing literature calibration procedure. Results show that the proposed method allows for effective controller tuning and leads to performing leakage reduction‐oriented real time control of pressures.

Select this Article		Regional Estimation of Stormwater Management Parameters in Florida David A. Chin Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000196 Posted ahead of print 26 September 2011 Full Text: \| Download PDF
	+ -	Show Abstract Stormwater management parameters that are significantly influenced by local climatic conditions are the runoff coefficient (C) and the water‐quality volume (WQV). Two classes of methods were investigated for estimating regional variations in C and WQV in Florida: interpolation methods and cluster‐analysis methods. The results show that the inverse‐distance‐squared (IDW‐2) interpolation method based on 45 reference stations distributed throughout the state provides the most accurate estimates of C and WQV, with a relative mean absolute error (RMAE) of 9% in estimating C and a RMAE of 13–18% in estimating WQV. Although cluster means provide less accurate estimates of C and WQV, cluster analyses show that Florida can be divided into three regions with similar values of C and five regions with similar values of WQV. Cross validation shows that using cluster means instead of the IDW‐2 method increases the RMAE by about 20% when estimating either C or WQV. A site‐specific example illustrates the roles of C and WQV in the design of stormwater management systems in Florida.

Select this Article		Incorporation of Variable‐Speed Pumping in Multiobjective Genetic Algorithm Optimization of the Design of Water Transmission Systems Wenyan Wu, Angus R. Simpson, Holger R. Maier, and Angela Marchi Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000195 \| Cited 1 time Posted ahead of print 26 September 2011 Full Text: \| Download PDF
	+ -	Show Abstract Global warming caused by human activities presents serious global risks. Individuals, governments and industries need to be more energy efficient and contribute to the mitigation of global warming by reducing their greenhouse gas (GHG) emissions. In previous research, GHG emission reduction has been identified as one important criterion in improving the sustainability of urban infrastructure and urban water systems. Within the water industry, opportunities exist for reducing GHG emissions by improving pumping efficiency via the use of variable‐speed pumps (VSPs). Previously, VSPs have been used in the optimization of the operation of existing water distribution systems (WDSs). However, in WDS design optimization problems, fixed‐speed pumps (FSPs) are commonly used. In this study, a pump power estimation method, developed using a false position method based optimization approach, is proposed to incorporate VSPs in the conceptual design or planning of water transmission systems (WTSs), using optimization. This pump power estimation method is implemented within the solution evaluation process via a multiobjective genetic algorithm approach. A case study is used to demonstrate the application of the pump power estimation method in estimating pump power and associated energy consumption of VSPs and FSPs in WTS optimization. In addition, comparisons are made between variable‐speed pumping and fixed‐speed pumping in multiobjective WTS optimization accounting for total cost and GHG emissions. The results show that the use of variable‐speed pumping leads to significant savings in both total cost and GHG emissions from WTSs for the case study considered.

Select this Article		Water Management Adaptations to Prevent Loss of Spring‐Run Chinook Salmon in California under Climate Change Lisa C. Thompson, Marisa I. Escobar, Christopher M. Mosser, David R. Purkey, D. Yates, and Peter B. Moyle Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000194 Posted ahead of print 31 August 2011 Full Text: \| Download PDF
	+ -	Show Abstract Spring‐run Chinook salmon (Oncorhynchus tshawytscha) are particularly vulnerable to climate change because adults over‐summer in freshwater streams before spawning in autumn. We examined streamflow and water temperature regimes that could lead to long‐term reductions in spring‐run Chinook salmon (SRCS) in a California stream and evaluated management adaptations to ameliorate these impacts. We used bias‐corrected and spatially downscaled climate data from six General Circulation Models and two emission scenarios for the period 2010 – 2099, as input to two linked models: WEAP to simulate weekly mean streamflow and water temperature in Butte Creek, California that were used as input to SALMOD, a spatially explicit and size/stage structured model of salmon population dynamics in freshwater systems. For all climate scenarios and model combinations, WEAP yielded lower summer base flows and higher water temperatures relative to historical conditions, while SALMOD yielded increased adult summer thermal mortality and population declines. Of management adaptations tested, only ceasing water diversion for power production from the summer holding reach resulted in cooler water temperatures, more adults surviving to spawn, and extended population survival time, albeit with a significant loss of power production. The most important conclusion of this work is that long‐term survival of SRCS in Butte Creek is unlikely in the face of climate change and that simple changes to water operations are not likely to dramatically change vulnerability to extinction.

Select this Article		An Effective Approach for Solving Battle of Water Calibration Network Problem Zheng Yi Wu and Thomas M. Walski Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000193 Posted ahead of print 27 August 2011 Full Text: \| Download PDF
	+ -	Show Abstract This paper presents an effective approach for calibrating an extended period simulation (EPS) model of water distribution system. Using the benchmark model calibration problem, set up for Battle of Water Calibration Networks (BWCN), the EPS model calibration is solved in a progressive manner, optimizing model parameters plus engineering judgments. The model calibration approach consists of multiple steps, including (1) constructing the initial EPS model with the given system and SCADA data; (2) calibrating pipe properties and pump curves for static and fire flow test data; and (3) calibrating EPS model demands and controls for given SCADA data over 167 hours. The calibration was iteratively conducted per District Meter Area (DMA) and then fine tuned for the whole system. While the field data contained some noise, good model calibration has been achieved for BWCN. Using the practically measurable hydraulic attributes of pump flows, pressures and tank levels provided for BWCN, the performance of the calibrated model is compared with those calibrated by fourteen teams around the world participated in the BWCN.

Select this Article		A GIS‐Based Decision Support System for Dam Break Flood Management under Uncertainty with Two Dimensional Numerical Simulations Honghai Qi and Mustafa S. Altinakar Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000192 Posted ahead of print 27 August 2011 Full Text: \| Download PDF
	+ -	Show Abstract A GIS‐based decision support system has been developed for dam break flood management based on realistic two dimensional flood simulations. With the ability of interacting with and use classified Remote Sensing (RS) image layers and other GIS feature layers like zoning layer, survey database and census block boundaries, it can be used for flood damage calculations and loss of life estimations. It also provides a user friendly interface which allows construction of user defined criteria, such as stage‐damage curves, running computations and visualization of the results. Monte Carlo Simulation method is used to take into account uncertainties in various variables and parameters, and event tree analysis is used to estimate the population dynamics. The analysis of a dam break flood management strategy for Sinclair Dam in Milledgeville, Georgia is chosen as a case study to demonstrate the capabilities of the decision support system. The test results validated by HEC‐RAS and HEC‐FDA software indicate that this new system provides a very versatile and reliable environment for estimating various flood damage, and may greatly enhance decision making process for future design of the flood proofing facilities.

Select this Article		The Battle of the Water Calibration Networks (BWCN) Avi Ostfeld, Elad Salomons, Lindell Ormsbee, James G. Uber, Christopher M. Bros, Paul Kalungi, Richard Burd, Boguslawa Zazula‐Coetzee, Teddy Belrain, Doosun Kang, Kevin Lansey, Hailiang Shen, Edward McBean, Zheng Yi Wu, Tom Walski, et al. Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000191 \| Cited 1 time Posted ahead of print 19 August 2011 Full Text: \| Download PDF
	+ -	Show Abstract Calibration is a process of comparing model results with field data and making the appropriate adjustments so that both results agree. Calibration methods can involve formal optimization methods or manual methods where the modeler informally examines alternative model parameters. The development of a calibration framework typically involves: (1) definition of the model variables, coefficients, and equations, (2) selection of an objective function to measure the quality of the calibration, (3) selection of the set of data to be used for the calibration process, and (4) selection of an optimization/manual scheme for altering the coefficient values in the direction of reducing the objective function. Hydraulic calibration usually involves the modification of system demands, fine‐tuning the roughness values of pipes, altering pump operation characteristics, and adjusting other model attributes that affect simulation results, and in particular those that have significant uncertainty associated with their values. From the above steps it is clear that model calibration is neither unique nor a straightforward technical task. The success of a calibration process depends on the modeler's experience and intuition, as well as on the mathematical model and procedures adopted for the calibration process. This paper provides a summary of the Battle of the Water Calibration Networks (BWCN), the goal of which was to objectively compare the solutions of different approaches to the calibration of water distribution systems through application to a real water distribution system. Fourteen teams from academia, water utilities, and private consultants participated. The BWCN outcomes were presented and assessed at the 12th Water Distribution Systems Analysis (WDSA 2010) conference in Tucson, Arizona, September 2010. This manuscript summarizes the BWCN exercise and suggests future research directions for water distribution systems calibration.

Select this Article		Demand Components in Water Distribution Network Analysis O. Giustolisi and T. M. Walski, F. ASCE Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000187 Posted ahead of print 13 August 2011 Full Text: \| Download PDF
	+ -	Show Abstract Solving water distribution network hydraulics depends to a great extent on demand representation in the related simulation models. The classical approach of simulation models for water distribution networks (WDNs) is described as demand‐driven. The demands are fixed a priori in the model as an assumption or from field observations. Recently a more realist approach to predict the hydraulic system behavior, described as head/pressure‐driven, better accounts for the fact that the demands depend in some ways on head status of the network. Thus, this paper presents a comprehensive view of demands in the enhanced WDN simulation models including considerations of human‐based, volume‐based, uncontrolled orifice‐based and leakage‐based demands as distinct types of network outflows. The paper proposes and discusses the representation of each type of demand in a comprehensive framework which is consistent with the hydraulic principles and the specific working condition.

Select this Article		A Simplified Procedure for Water Distribution Networks Reliability Assessment Carlo Ciaponi, Luigi Franchioli, and Sergio Papiri Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000184 Posted ahead of print 6 August 2011 Full Text: \| Download PDF
	+ -	Show Abstract This work describes a simple procedure for the analysis of water distribution system (WDS) performance. It is based on the reliability assessment of a WDS during failure states due to the unavailability of a pipe (maintenance or repair), taking into account the probability of the failure events. The procedure may consider changes in daily demand using patterns defined to represent seasonal trends. Applying this method to a network with around 200 pipes demonstrates its usefulness, especially when the aim is to objectively compare different design solutions. The procedure takes also into account variations in design parameters such as an increase in water demand and/or a drop in hydraulic conductance due to pipe lining degradations (corrosion or deposits).

Select this Article		Influence of Deregulated Electricity Markets on Hydropower Generation and Downstream Flow Regime Jordan D. Kern, Gregory W. Characklis, Martin W. Doyle, Seth Blumsack, and Richard B. Whisnant Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000183 Posted ahead of print 6 August 2011 Full Text: \| Download PDF
	+ -	Show Abstract The flow regime of rivers is a complex, but important measure of environmental quality, and one that can be significantly impacted by conventional hydropower generation. While traditional hydropower scheduling creates a periodicity in downstream flows corresponding to seasonal and daily electricity demand patterns, deregulated electricity markets may provide financial incentives to further alter flows, as utilities respond to hourly market dynamics. This study investigates the potential for deregulated markets to impact both a hydropower utility's revenue stream and downstream flow regimes. Six operating scenarios are explored: (i–ii) full‐market participation (including real‐time energy), with and without flow reregulation; (iii) day‐ahead market only; and (iv–vi) run‐of‐river operations (ROR), with and without flood control and flow reregulation. Results suggest that, relative to a day‐ahead only scenario, the scale of any differences in flow regime resulting from full‐market participation is relatively small compared to the additional revenue generating potential of such a strategy. Implementing a run‐of‐river policy frequently yields ‘more natural’ flow regimes than the day‐ahead only scenario; but, in some cases these improvements are modest, and in others the ROR scenarios exacerbate deviation from unregulated flows. Regardless, the effects of implementing an ROR strategy come at a substantial cost in terms of foregone hydropower revenue.

Select this Article		A 550‐Year Reconstruction of Streamflow Variability in Spring Valley, Nevada, USA Scotty Strachan, Franco Biondi, and Joseph Leising Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000180 Posted ahead of print 6 August 2011 Full Text: \| Download PDF
	+ -	Show Abstract Spring Valley, Nevada, is one of several areas proposed for the pumping and export of ground water to Las Vegas by the Southern Nevada Water Authority. Long‐term annual‐to‐decadal variability of water supply in the region is not well understood, so we used tree‐ring records to develop a longer baseline of variability in streamflow and drought episodes. Long‐lived (up to about 600 years), climatically sensitive single‐leaf pinyon pine (Pinus monophylla) trees within the Cleve Creek watershed provided a 550‐year (1458–2007) tree‐ring chronology that was compared to water year mean monthly runoff from USGS gage 10243700. Using a proxy record from within the watershed under study increased confidence in the statistical relationships used for streamflow reconstruction. Linear correlation between the tree‐ring chronology and the streamflow record over 34 years of overlap was 0.73, explaining 53% of the instrumental variance. After comparison with multiple linear regression and linear regression with transformed data, we used the line of organic correlation (LOC) method to develop a streamflow reconstruction with water‐year resolution from 1458 to 2007. During these 550 years, a total of 257 wet and dry episodes were quantified according to their duration, magnitude, and peak. The longest episode was 1848–1855 (an 8‐year wet spell); the greatest magnitude belonged to the drought of the mid‐1600s (1652–1655); the 3 highest peaks all corresponded to dry episodes, 1506–1508, 1590, and 1933–1936. Using a numerical scoring rule, the 1930s drought (1933–1936) was in 8^th position, making it one of the most remarkable episodes in the past half millennium. This result is not entirely consistent with recent dendroclimatic reconstructions for the eastern Sierra, suggesting that regional drought severity varies by locality within the Great Basin. Evaluating the responses of trees at multiple elevations to various local climate and hydrological parameters through in‐situ monitoring will help refine tree‐ring reconstructions of past ecohydrological conditions.

Select this Article		Investigating the Sensitivity of U.S. Streamflow and Water Quality to Climate Change: The U.S. EPA Global Change Research Program's “20 Watersheds” Project T. E. Johnson, J. B. Butcher, A. Parker, and C. P. Weaver Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000175 Posted ahead of print 14 July 2011 Full Text: \| Download PDF
	+ -	Show Abstract The U.S. EPA's Global Change Research Program (GCRP) recently began an effort to address gaps in our knowledge of the sensitivity of U.S. streamflow, nutrient (N and P), and sediment loading to potential future climate change, and the methodological challenges associated with integrating existing tools (e.g., climate models, land‐use models, watershed models) and datasets to address these scientific questions. The study is based on watershed modeling in 20 large U.S. watersheds. The purpose of this paper is to describe the overall structure of this ongoing effort — our methods, sites, models, and scenarios — as well as discuss preliminary results generated to date for a subset of the watersheds. Specifically, we review a representative set of modeling results that encompass the full suite of sensitivity tests we are exploring in this project. These results illustrate a number of key methodological issues, sensitivities, and uncertainties associated with carrying out these types of climate change‐hydrologic impacts assessments, including: the sensitivity of simulated changes to the watershed model used; the sensitivity of simulated changes to climate model and downscaling approach used; and the interaction between climate change and other key forcing factors, specifically urbanization and change in atmospheric CO₂ concentration. In addition, this suite of results provides an overview of the response to climate change in different geographic regions and the different sensitivities of a variety of flow and water quality endpoints.

Select this Article		Staged Climate Change Adaptation Planning for Water Supply in Amman, Jordan P. A. Ray, P. H. Kirshen, and D. W. Watkins, Jr. Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000172 Posted ahead of print 11 July 2011 Full Text: \| Download PDF
	+ -	Show Abstract This research develops a multistage stochastic linear programming (LP) model to assist in the process of water system planning and management under demographic and climate change in Amman, Jordan, over the next 75 years. Climate change is projected to have a gradual exacerbating effect on Amman's water stress over the next century, and water resources management strategies and policies put in place now will likely influence water use patterns for generations to come. A multi‐stage decision model allows the identification of both adaptation strategies that should be implemented now, and actions likely to be needed later, depending upon future climate and demographic conditions. For Amman, the model recommends that household water reuse be expanded immediately, large‐scale wastewater reclamation begin within 25 years, and mega‐scale water import projects be postponed for several decades. Although these recommendations for the future will almost certainly change as additional information is acquired, by identifying now the actions most likely to be needed in the future, options for their implementation can be reserved, and feasibility studies begun.

Select this Article		Incorporating Climate Uncertainty in a Cost Assessment for a New Municipal Source Water Erin Towler, Bob Raucher, Balaji Rajagopalan, Alfredo Rodriguez, David Yates, and R. Scott Summers Journal of Water Resources Planning and Management doi:http://dx.doi.org/10.1061/(ASCE)WR.1943-5452.0000150 Posted ahead of print 7 March 2011 Full Text: \| Download PDF
	+ -	Show Abstract Though new water supply source development has always required planning under many forms of uncertainty, climate change presents an added dimension that may exacerbate supply and water quality challenges. Hence, new decision‐support tools are needed, and in this paper an approach that incorporates the uncertainty of climate variability and change into a cost assessment framework for a municipal drinking water provider in Colorado is developed and applied. The water utility provider is developing a new source of water supply, but treatment costs are relatively high due to the advanced processes needed to treat the water to desired standards. Furthermore, the new water source has variable salinity concentrations that are not removed by any of the implemented treatment processes, requiring blending with an existing lower salinity water source. This results in an increase in the finished water salinity (as compared with the existing water source), which can have negative impacts on customer satisfaction and the life‐span of water‐using appliances. To plan for the development of this water supply source, an approach is proposed to assess the potential treatment and residential costs associated with the blending of the new water source with an existing source under climate uncertainty. Uncertainty from climate variability is captured through a previously developed stochastic streamflow and water quality simulation method that utilizes climate change scenarios. Results show that the proposed blend strategies incur increased treatment costs and economic impacts for customers. Specifically, a 30% reduction in annual flows due to climate change translates into a 12% treatment cost increase and a 22% rise in residential costs.