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Select this Article		Behaviour of Sediment Clouds in Waves Bing Zhao, Adrian W. K. Law, Zhenhua Huang, E. Eric Adams, and Adrian C. H. Lai Journal of Waterway, Port, Coastal, and Ocean Engineering doi:http://dx.doi.org/10.1061/(ASCE)WW.1943-5460.0000167 Posted ahead of print 18 May 2012 Full Text: \| Download PDF
	+ -	Show Abstract The effects of regular surface waves on the descent of instantaneously released sediments were investigated experimentally. The detailed wave characteristics, including wave height (H), wave period (T), and wave phase of release were controlled systematically through a wave synchronization system. The results showed that the sediment cloud was passively advected by the wave orbital motion, and there was no significant phase lag between the sediments and surrounding water particles. The motion of the centre of mass and the growth rate of the sediment cloud averaged over four representative wave phases of release were found to be similar to those in stagnant ambient condition. However, a shift (in the range of ±H/2) in the horizontal equilibrium position of the oscillatory motion was observed, and was found to be related to the wave phase of release. A Passive Advection Model was proposed to predict the motion of a sediment cloud in the wave environment by superimposing the wave orbital velocity onto the descent velocity of the sediment cloud induced by buoyancy excess. The prediction was found to be in reasonable agreement with the experimental data.

Select this Article		Prediction of Coastal Far Infra‐Gravity Waves from Sea‐Swell Spectra S. Thiebaut, P. McComb, and R. Vennell Journal of Waterway, Port, Coastal, and Ocean Engineering doi:http://dx.doi.org/10.1061/(ASCE)WW.1943-5460.0000166 Posted ahead of print 17 May 2012 Full Text: \| Download PDF
	+ -	Show Abstract Far Infra Gravity Waves (FIGWs) with periods of 2–64 minutes can reduce the underkeel clearance for vessels in transit to ports, and cause resonance in and around harbours and bays that amplifies low frequency current flows. Sea level records from six tide gauges along the east coast of New Zealand and the Chatham Islands are compared with offshore weather systems and spectral statistics from the Gravity Wave (GW) band (including both sea and swell waves) from wave buoys and hindcast sources. An empirical formula to predict coastal FIGWs is developed, based on the offshore GW significant wave height, associated peak period, and spectral width parameter. This formula is able to explain the occurrence of most FIGW events, confirming that most of the FIGW energy arriving at the coast is directly associated with GW energy. However, several discrete events were not predicted by the technique, and reverse ray tracing was applied to explore the origin of these events. In the light of these findings, previously reported long wave events on the coast of New Zealand are re‐examined using the newly developed long wave predictor.

Select this Article		Assessing Factors Affecting the Thermal Properties of a Passive Thermal Refuge Using Three‐Dimensional Hydrodynamic Flow and Transport Modeling Jeremy Decker, Eric Swain, Brad Stith, and Catherine Langtimm Journal of Waterway, Port, Coastal, and Ocean Engineering doi:http://dx.doi.org/10.1061/(ASCE)WW.1943-5460.0000165 Posted ahead of print 17 May 2012 Full Text: \| Download PDF
	+ -	Show Abstract Everglades restoration activities may cause changes to temperature and salinity stratification at the Port of the Islands (POI) marina, which could affect its suitability as a cold‐weather refuge for manatees. To better understand how the Picayune Strand Restoration Project (PSRP) may alter this important resource in Collier County in southwestern Florida, the USGS has developed a three‐dimensional hydrodynamic model for the marina and canal system at POI. Empirical data suggest that manatees aggregate at the site during winter because of thermal inversions that provide warmer water near‐bottom that appears to only occur in the presence of salinity stratification. To study these phenomena, the Environmental Fluid Dynamics Code (EFDC) simulator was used to represent temperature and salinity transport within POI. Boundary inputs were generated using a larger 2D model constructed with the Flow and Transport in a Linked Overland‐Aquifer Density Dependent System (FTLOADDS) simulator. Model results for a representative winter period match observed trends in salinity and temperature fluctuations and produce temperature inversions similar to observed values. Modified boundary conditions, representing proposed PSRP alterations, were also tested to examine the possible effect on the salinity stratification and temperature inversion within POI. Results show that during some periods, salinity stratification is reduced resulting in a subsequent reduction in temperature inversion when compared to the existing‐conditions simulation. This may have an effect on POI's suitability as a passive thermal refuge for manatees and other temperature‐sensitive species. Additional testing was completed to determine the important physical relationships affecting POI's suitability as a refuge.

Select this Article		Distributions of Wave Heights in Time Domain in Stationary Sea States Paolo Boccotti, Felice Arena, and Vincenzo Fiamma Journal of Waterway, Port, Coastal, and Ocean Engineering doi:http://dx.doi.org/10.1061/(ASCE)WW.1943-5460.0000164 Posted ahead of print 17 May 2012 Full Text: \| Download PDF
	+ -	Show Abstract About 6,300,000 pressure head waves beneath the sea surface were recorded by an array of 26 transducers aligned orthogonally to the coastline of Reggio Calabria, Italy. The dataset covered spectra from very narrow unimodal to very broad multimodal and waves from shallow to deep waters. Herein, the quasi‐determinism (QD) theory is proven to be very effective in predicting the probability of large wave heights as well as the period and particle acceleration of these waves both on deep and shallow waters. In addition, the Tayfun model for predicting the probability of large wave heights is also proven to be highly effective.

Select this Article		Numerical Modeling of the Influence of the Beach Profile on Wave Run‐Up Luciano Soldini, Matteo Antuono, and Maurizio Brocchini Journal of Waterway, Port, Coastal, and Ocean Engineering doi:http://dx.doi.org/10.1061/(ASCE)WW.1943-5460.0000163 Posted ahead of print 17 May 2012 Full Text: \| Download PDF
	+ -	Show Abstract An analysis of the run—up over different beach profiles is performed to evaluate the influence of the seabed shape on shore flooding. The analysis has been carried out on the basis of numerical solutions of the Nonlinear Shallow Water Equations. The chosen solver has been shown to provide reliable (both quantitatively and qualitatively) run—up results by comparing numerical solutions (of both solitary and regular waves) with the only available analytical solution “forced” by a localized topographic change. The run—up patterns on both a natural beach profile and three simpler and schematic profiles, derived from it, have been evaluated. Different wave conditions (both random and groups) have been used for a total amount of 96 different cases of inundation. Results are expressed in terms of both maximum (Z_max) and steady—state (Z_steady) run—up. It is found that both types of run—up depend on the offshore variable , as suggested by several available studies, and that, for all tested cases, random waves induce largest Z_max than wave groups. The largest Z_max is induced by the composite−planar profile for both random waves and groups. An important similarity is found for both Z_max and Z_steady induced by all wave types over the natural and equilibrium profiles, this giving further support to the use of an equilibrium profile as representative of the natural profile. Attempts at finding an “equivalent planar beach” highlight unavoidable difficulties in choosing such a profile and reinforce the idea that the concept of “equivalent planar beach” cannot bridge dynamics occurring from the depth of closure to the run‐up. More likely such a concept is only suitable to describe dynamics which are local to the foreshore.

Select this Article		Backfilling of a Scour Hole around a Pile in Waves and Current B. Mutlu Sumer, Thor U. Petersen, Luca Locatelli, Jørgen Fredsøe, Rosaria E. Musumeci, and Enrico Foti Journal of Waterway, Port, Coastal, and Ocean Engineering doi:http://dx.doi.org/10.1061/(ASCE)WW.1943-5460.0000161 Posted ahead of print 27 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract This paper presents the results of an experimental investigation of backfilling of scour holes around circular piles. Scour hole around a pile is generated either by a current, or by a wave. Subsequently the flow climate is changed from current to wave, or to combined wave and current; or from wave to a smaller wave, leading to backfilling of the scour hole. The investigation has shed light onto the mechanism behind the backfilling process. The results show that the scour depth corresponding to the equilibrium state of backfilling is the same as that corresponding to the equilibrium state of scour around the pile for the same wave (or combined wave and current) climate. The time scale of backfilling has been determined as a function of three parameters, namely (1) the Keulegan‐Carpenter number of the initial wave or the current (which generates the initial scour hole); (2) that of the subsequent wave which backfills the scour hole; and (3) the Shields parameter associated with the latter wave, for live‐bed conditions. In the case of combined wave and current, the current‐to‐wave‐velocity ratio is also involved. The time scale of the backfilling process is completely different from that of scour. The time scale of backfilling is much larger than that of scour when the Keulegan‐Carpenter number associated with the backfilling is KC_f<O(10). (typical wind farm application), while the time scale of backfilling can be smaller than that of scour when KC_f≫O(10).

Select this Article		Real‐Time Tsunami Prediction by Inversion Method Using Offshore Observed GPS Buoy Data — A Case Study for Nankaido — Tomohiro Yasuda and Hajime Mase, M. ASCE Journal of Waterway, Port, Coastal, and Ocean Engineering doi:http://dx.doi.org/10.1061/(ASCE)WW.1943-5460.0000159 Posted ahead of print 27 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract In Japan, the probability of Tokai, Tonankai and Nankai earthquake occurring in the early 21st century is high. Given this likelihood, estimating the resulting tsunami in real time is desirable. This study details an inversion method for real‐time tsunami predictions using only observed offshore tsunami data. Numerical experiments demonstrate that: 1) the tsunami wave source is estimated fairly well using the inversion method, as compared to the initial sea surface displacement calculated from the earthquake fault model; 2) the tsunami profiles are predicted with great accuracy at coastal locations of interest; and, 3) the profiles are accurately and easily updated using a longer duration of observed tsunami data after an earthquake. This study also investigates techniques to improve the accuracy of the forecasts: screening optimal locations for offshore GPS buoys, using a longer period of observation data, and decreasing the duration of the tsunami prediction. These techniques illustrate the practical application of this method for tsunami forecasting.

Select this Article		Global Sea Level Projections to 2100 Using Methodology of the Intergovernmental Panel on Climate Change James R. Houston Journal of Waterway, Port, Coastal, and Ocean Engineering doi:http://dx.doi.org/10.1061/(ASCE)WW.1943-5460.0000158 Posted ahead of print 23 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract Forecasts of sea level rise by 2100 have such a wide range that objective planning is difficult. In 2007 the Intergovernmental Panel on Climate Change (IPCC) forecast a sea level rise from 1990 to 2100 of between 0.18 and 0.59 m but did not completely consider contributions from Greenland and Antarctica in determining the upper limit. Recent projections by others have been larger, typically 1‐2 m, with Greenland and Antarctica being the greatest contributors. However, these projections are usually maximum possible rises without probabilities of occurrence, whereas the maximum IPCC projection is at the 95%‐confidence level with a 2.5% probability of being equaled or exceeded. Project planning and design generally require projections with associated probabilities in order to determine risk. This paper shows what worldwide tide gauge data tell us about sea level rise trends and accelerations in the 20^th century and satellite altimeter recordings tell us about the rise since the early 1990s. Using IPCC methodology, sea level projections with associated probabilities are made from 1990 to 2100. Projections of Greenland and Antarctica contributions are estimated based on satellite measurements of current ice‐mass‐loss trends and accelerations and then added to contributions from thermal expansion and melting of glaciers and ice caps based on the latest information. Sea level rise projections from 1990 to 2100 are 0.18, 0.48, and 0.82 m at 5%‐, 50%‐, and 95%‐confidence levels respectively.

Select this Article		A Method for Estimating Future Hurricane Flood Probabilities and Associated Uncertainty Jennifer L. Irish, M. ASCE and Donald T. Resio, M. ASCE Journal of Waterway, Port, Coastal, and Ocean Engineering doi:http://dx.doi.org/10.1061/(ASCE)WW.1943-5460.0000157 Posted ahead of print 20 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract Reliable hurricane flood probability estimates are essential for effective management and engineering in the coastal environment. Yet, uncertainty in future climate conditions presents a challenge for assessing future flood probabilities. Studies suggest that in the future sea‐level rise may accelerate and hurricanes may intensify and occur less or more often. Here, methods are presented for incorporating sea‐level rise and future hurricane conditions into extreme‐value flood statistics analysis. By considering an idealized coast, surge response functions are used with joint probability statistics to define time‐varying continuous probability mass functions for hurricane flood elevation. Uncertainty in the flood estimates introduced by uncertainty in future climate is quantified by considering variance in future climate and sea level projections. It will be shown that future global warming can increase the flood elevation at a given return period by 1 to 3% per decade, but that climate‐related uncertainty only marginally contributes to the overall uncertainty associated with hurricane flood statistics. Finally, it will be demonstrated that adaptive management practices are the most effective means of optimizing future coastal engineering activities in the face of climate change.

Select this Article		Experimental Study on the Scour around a Mono Pile in Breaking Waves Anders Wedel Nielsen, B. Mutlu Sumer, Sebastian Schjelde Ebbe, and Jørgen Fredsøe Journal of Waterway, Port, Coastal, and Ocean Engineering doi:http://dx.doi.org/10.1061/(ASCE)WW.1943-5460.0000148 Posted ahead of print 12 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract The scour process around mono piles caused by breaking waves is studied experimentally using regular waves. The use of regular waves is conservative and made it possible to avoid scour phenomena caused by non‐breaking waves, such as scour generation and back filling. The waves were breaking on a flat sand section after shoaling on a mildly sloping ramp. Different mono piles were exposed to plunging breakers, breaking at different distances from the pile. It is found that the scour is caused by turbulence generated by the breaking and diverted towards the bottom by the pile. The maximum scour depth found is approximately 0.60D. This is smaller than the scour observed around piles exposed to current, but in some cases an order of magnitude larger than the scour caused by non‐breaking waves. This is apparently especially true for larger piles.

Select this Article		Anthropogenic Effects on Coastal Sediment Fluxes in a Non‐Tidal Gulf System Rafał Ostrowski, Zbigniew Pruszak, Aleksander Babakov, and Boris Chubarenko Journal of Waterway, Port, Coastal, and Ocean Engineering doi:http://dx.doi.org/10.1061/(ASCE)WW.1943-5460.0000156 Posted ahead of print 11 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract The paper presents the results of studies of the physical processes observed in the coastal zone of the eastern part of the Gulf of Gdańsk, from the Vistula river mouth (Poland) to Cape Taran (Russia, Kaliningrad Oblast), since it is under severe environmental and anthropogenic pressure. We present investigations of wind climate, wind‐driven currents, deep‐water waves, nearshore sediment fluxes, engineering activities and shoreline changes/response at eight study sites selected along the coast of the study area. Four of the sites are located on the Polish side and four on the Russian side of the state border. An assessment of the anthropogenic impact on coastal litho‐ and morphodynamics (local sediment fluxes and shoreline response) as a function of different local hydrodynamic climates is performed. Key coastal locations in the Gulf (the Vistula river mouth, the Baltijsk Strait with the harbor of Baltijsk and the mining plants near Jantarnyj), where natural sediment morphological processes have been affected by human activities, are particularly analyzed. It is seen that even in the same system (Gulf of Gdańsk), sites located close to each other and subject to similar anthropogenic activities, can display quite different evolutionary patterns. In some cases, anthropogenic effects may be secondary to natural background conditions.

Select this Article		Pore Pressure, Stress Distributions and Instantaneous Liquefaction of Two‐Layer Soil under Waves M. B. Can Ulker, Ph.D., A. M. ASCE Journal of Waterway, Port, Coastal, and Ocean Engineering doi:http://dx.doi.org/10.1061/(ASCE)WW.1943-5460.0000155 Posted ahead of print 11 April 2012 Full Text: \| Download PDF
	+ -	Show Abstract In this paper, shear, effective stress and pore pressure distributions of two‐layer porous soils subjected to harmonic waves are presented. The instability of the porous soil due to wave loading is investigated in terms of instantaneous liquefaction. The governing equations are written in their fully dynamic form and possible simplifications are introduced. Finite element models are developed for each formulation and numerical results are verified with their corresponding analytical solutions that are also developed here. Then the problem of a two‐layer soil under waves both in an open doman and in front of a vertical wall is studied in terms of dynamic response variations and regions of instantaneous liquefaction. Both linear and non‐linear waves are considered. Finally, a number of parametric studies to investigate the effect of a surface clay layer, inertial terms in the equations, various soil and wave parameters as well as wave non‐linearity on the dynamic behavior and instability are carried out. The results indicate that the two‐layer response is significantly different from that of a conventional single layer approach. Inertial terms are partially important in terms of stress variations depending on the wave and seabed parameters. The clay layer reduces the amount of liquefaction protecting the underlying seabed until it reaches a certain thickness beyond which the depth of liquefaction increases. Wave period, inertial terms and wave non‐linearity affect the response for an open domain and in the presence of a wall, mostly leading to more liquefaction.

Select this Article		Probabilistic Projection of Mean Sea Level and Coastal Extremes Jayantha Obeysekera, P.E., M. ASCE, Joseph Park, P.E., Michelle Irizarry‐Ortiz, P.E., Jenifer Barnes, and Paul Trimble Journal of Waterway, Port, Coastal, and Ocean Engineering doi:http://dx.doi.org/10.1061/(ASCE)WW.1943-5460.0000154 Posted ahead of print 29 March 2012 Full Text: \| Download PDF
	+ -	Show Abstract Fundamental uncertainties governing sea level rise projections are associated with the rate of acceleration in global sea level rise and the local factors affecting relative sea level. Recent models and observations of global ice‐sheets and their contributions to sea level, as well as climate models, suggest that significant sea level acceleration is eminent, yet observational data from tide gauges and satellites has not yet found rates consistent with some of the projections. In order to allow coastal planners a way to incorporate the uncertainties of acceleration we propose a synthesis of observed sea level data with selected distributions of acceleration and the current rate of rise to provide probabilistic estimates of future sea levels. The resulting distributions can be adopted in a risk‐based framework to assess project vulnerability. We expect that as geophysical understanding of the climate forced sea level dynamics improve, the selection and veracity of these distributions and their sea level projections will improve. As a case study, the methodology is demonstrated by application to Key West in southern Florida.

Select this Article		A Formula to Predict Transmission for II ‐Type Floating Breakwaters Piero Ruol, Luca Martinelli, and Paolo Pezzutto Journal of Waterway, Port, Coastal, and Ocean Engineering doi:http://dx.doi.org/10.1061/(ASCE)WW.1943-5460.0000153 Posted ahead of print 19 March 2012 Full Text: \| Download PDF
	+ -	Show Abstract The aim of this paper is to define a simple and useful formula to predict wave transmission for a common type of floating breakwater (FB), supplied with two lateral vertical plates protruding downwards, named π‐type FB. Eight different models, with mass varying from 16 to 76 kg, anchored with chains, have been tested in the wave flume of the Maritime Laboratory of Padova University, under irregular wave conditions. Water elevation in front and behind the structure has been measured with two arrays of four wave gauges. Our starting point for the prediction of wave transmission was the classical relation established by Macagno in 1954. His relation has been derived for a box‐type fixed breakwater assuming irrotational flow. Consequently he significantly underestimated transmission for short waves and for large drafts. This paper proposes an empirical modification of his relation to properly fit the experimental results and a standardised plotting system of the transmission coefficient, based on a simple non‐dimensional variable. This variable is the ratio between the peak period of the incident wave and an approximation of the natural period of the heave oscillation. A fairly good accuracy of the prediction is found analysing the data in the literature relative to variously moored π‐type FBs, tested in small scale wave tanks under regular and irregular wave conditions.

Select this Article		Seasonal to Decadal Variability of Longshore Sand Transport at the Northwest Coast of Portugal Ana Nobre Silva, Rui Taborda, Xavier Bertin, and Guillaume Dodet Journal of Waterway, Port, Coastal, and Ocean Engineering doi:http://dx.doi.org/10.1061/(ASCE)WW.1943-5460.0000152 Posted ahead of print 14 March 2012 Full Text: \| Download PDF
	+ -	Show Abstract Longshore sediment transport (LST) is a major driver of coastal evolution. However, despite the recognition that it presents an unsteady behavior at seasonal scale, the variability at longer term scales (interannual and decadal) is still far from being properly acknowledged. The present work contributes to the understanding of the seasonal to decadal variability of the LST benefiting from recent developments in wave hindcast modelling. This work was developed for the northwest coast of Portugal which is fully exposed to the highly energetic wave regime generated at the northeast Atlantic Ocean that induces unusually large LST rates. Hindcast offshore waves, between 1953 and 2010, were used as offshore forcing to deduce LST estimates. The mean annual LST, between 1953 and 2010, shows an irregular and non‐cyclic pattern. Computed mean annual LST, for this coastal stretch, is around one million cubic meters directed to the south, with yearly averages ranging from 108,000 m³.yr⁻¹ to 2,240,000 m³.yr⁻¹ always directed to the south. The maximum observed annual LST magnitude exceeds the mean magnitude by more than 100%. The variability in LST magnitude was found to be mainly related to autumn/winter months in response to the wave regime seasonality. Results show that to estimate the long‐term LST within an error about 20%, a period of about 10 years of data/observations is required. Interannual variability in the magnitude of the LST was found to be correlated (R² = 0.55) with the annual North Atlantic Oscillation (NAO) index. In the years where the NAO index was higher, the mean annual LST was generally greater than the long‐term average, while negative NAO index corresponds to lower than average LST estimates.

Select this Article		Determining Propeller Erosion at the Stern of a Berthing Ship Donal Ryan, BEng (Hons), CEng, Ph.D., M.I.C.E., M.I.E.I and G. A. Hamill, BSc (Hons) Ph.D. Journal of Waterway, Port, Coastal, and Ocean Engineering doi:http://dx.doi.org/10.1061/(ASCE)WW.1943-5460.0000151 Posted ahead of print 10 March 2012 Full Text: \| Download PDF
	+ -	Show Abstract This paper presents the findings from an experimental investigation in to the nature and extent of the scouring that occurs when a ship berths in front of a perpendicular quay wall within the confines of a harbor. It examines the interaction between the relative position of the quay wall to the central axis of the ship and the influence of angle of the vessel's rudder on the magnitude of the scouring produced. The experimental programme covered a range of sediment sizes, propeller diameters and speeds of rotation and rudder angles. Also, methods for calculating the depth of expected scour are presented in terms of initial semi‐empirical equations for the data range under investigation.

Select this Article		Study of Scour around Submarine Pipeline with a Rubber Plate or Rigid Spoiler in Wave Conditions Lipeng Yang, Yakun Guo, Bing Shi, Cuiping Kuang, Weilin Xu, and Shuyou Cao Journal of Waterway, Port, Coastal, and Ocean Engineering doi:http://dx.doi.org/10.1061/(ASCE)WW.1943-5460.0000150 Posted ahead of print 6 March 2012 Full Text: \| Download PDF
	+ -	Show Abstract This paper presents results from laboratory experimental model studies to investigate the scour by waves around the pipeline attached with a flexible rubber plate or rigid spoiler. The rubber plate is placed between the submarine pipeline and bed, while the rigid spoiler is attached at the top of the pipe. The scour around the pipeline with and without a rubber plate or a rigid spoiler under the regular and irregular waves are observed and measured for a range of pipe sizes, wave amplitudes and frequencies and the length of plate/the height of the spoiler. The experiments reveal that though the rigid spoilers can enhance the scour depth and extent (thus accelerating the self‐burial of pipe), they also has significant influence on both the upstream and downstream bed topography as sand ripples and dunes are formed. Rubber plates, on the other hand, can not only significantly increase the scour depth, but also has little effect on the upstream and downstream bed.. The experiments show that when the length of the plate is about 1.5 times of the pipe size, it provides the optimum performance in terms of the largest scour depth while restrict the impact on nearby beds for parameters investigated in this study.

Select this Article		An Analytical Solution for Long‐Wave Scattering by a Circular Island Mounted on a General Shoal Huan‐Wen Liu, Jian‐Jian Xie, and Zhang‐Hua Luo Journal of Waterway, Port, Coastal, and Ocean Engineering doi:http://dx.doi.org/10.1061/(ASCE)WW.1943-5460.0000149 Posted ahead of print 3 March 2012 Full Text: \| Download PDF
	+ -	Show Abstract In this paper, an analytical solution in the form of a Taylor series for long‐wave scattering by a cylindrical island mounted on a general shoal is given, where the water depth in the shoal region can be a real constant plus a power function of the radial distance; in other words, the crest of the shoal is not restricted to be on the still water level. It is found that the number of singular points of the long‐wave equation for this general shoal becomes two and the distribution of singular points becomes complicated, therefore the solution technique needs to be more sophisticated. Because of the generality of the location of the shoal crest, our analytical solutions find several classical analytical solutions to be its special cases, which include long‐wave scattering by a cylindrical island mounted on an idealized paraboloidal shoal, a cylindrical island mounted on an idealized conical shoal, a cylindrical island mounted on an idealized shoal and a cylindrical island located on a flat bottom. Naturally, the present analytical solution covers a much wider range of problems and is hence much more useful. Finally, using the current analytical solution, the effect of the shoal size to wave scattering pattern is investigated.

Select this Article		Beach Erosion and Recovery Nobuhisa Kobayashi, M. ASCE and Hooyoung Jung Journal of Waterway, Port, Coastal, and Ocean Engineering doi:http://dx.doi.org/10.1061/(ASCE)WW.1943-5460.0000147 Posted ahead of print 27 February 2012 Full Text: \| Download PDF
	+ -	Show Abstract Our capability for predicting beach and dune erosion has improved for the last three decades but the recovery of an eroded beach above the mean sea level (MSL) cannot be predicted at present. The cycle of beach erosion and recovery will need to be predicted for the long‐term maintenance of a sand beach with a dune for coastal flooding reduction. The cross‐shore numerical model CSHORE is extended and evaluated using natural beach erosion and recovery data along 16 cross‐shore lines spanning 5 km alongshore for the duration of 272 days. CSHORE predicts beach and dune erosion fairly well as has been shown in the previous comparisons. The bed load formula used in CSHORE is adjusted to predict the accreted beach profile with a berm. The computed beach profile evolutions are shown to be affected little by the alongshore gradient of the longshore sediment transport rate along the straight beach. The extended CSHORE predicts both erosion and accretion above MSL within a factor of about 2.

Select this Article		A Stochastic Model for Damage Accumulation in Rubble‐Mound Breakwaters Based on Compatibility Conditions and the Central Limit Theorem Carmen Castillo, Enrique Castillo, Alfonso Fernández‐Canteli, Rafael Molina, and Rebeca Gómez Journal of Waterway, Port, Coastal, and Ocean Engineering doi:http://dx.doi.org/10.1061/(ASCE)WW.1943-5460.0000146 Posted ahead of print 16 February 2012 Full Text: \| Download PDF
	+ -	Show Abstract Motivated by some damage accumulation modeling difficulties reported by Melby and Kobayashi, some suggestions on how to build consistent stochastic models for damage accumulation in breakwaters are given. The models avoid the selection of easy to use mathematical functions, which are replaced by those resulting from a set of properties that are expected in the model. It is shown how an inadequate selection of damage progression models leads to inconsistencies, which are avoided by using the proposed consistent mathematical structures. Dimensional analysis, compatibility conditions and the central limit theorem are the bases for building a model aiming at reproducing the stochastic damage progression on a breakwater due to general random wave actions. Four elements are identified as essential for a damage accumulation analysis: (a) the statistical distribution of the initial damage, (b) the mathematical structure of damage growth curves, (c) the damage function, that accounts for how the variables affect damage, and (d) the integral form in which damage accumulates, that permits to relate its random character to the normal distribution. These four elements are combined to derive a general structure of models for determining the damage produced by any wave history, and to obtain the evolution of densities of cumulative damage with time. Finally, the proposed methods are illustrated by means of a real case example provided by Melby and Kobayashi, and one of the models proposed by these authors is shown to be convenient to reproduce damage progression in breakwaters. The proposed method is valid not only for breakwaters but to other evolutive processes that appear in the maritime and coastal engineering field.

Select this Article		Matching Mean Sea Level Rise Projections to Local Elevation Datums Reinhard E. Flick, Kevin Knuuti, and Stephen K. Gill Journal of Waterway, Port, Coastal, and Ocean Engineering doi:http://dx.doi.org/10.1061/(ASCE)WW.1943-5460.0000145 Posted ahead of print 13 February 2012 Full Text: \| Download PDF
	+ -	Show Abstract A method is presented to consistently tie future mean sea level rise (MSLR) scenario projections to local geodetic and tidal datums. This extends U.S. Army Corps of Engineer (USACE) guidance for incorporating effects of future MSLR into coastal projects. While USACE relies on the National Oceanic and Atmospheric Administration (NOAA) 19‐year National Tidal Datum Epoch (NTDE) for its datum relationships, the approach proposed herein generalizes this guidance by choosing the appropriate 19‐year epoch centered on the start‐year of the MSLR scenario under consideration. The procedure takes into account local annual sea level variability, which confounds the matching to any given single year, while generalizing and preserving the 19‐year NTDE averaging long used by NOAA. Examples of the MSLR scenario matching procedure are shown using actual data and projections for La Jolla, CA and Sewells Point (Hampton Roads), VA.

Select this Article		Hydrodynamic Forces on Large Pipeline and Small Pipeline in Piggyback Configuration under Wave Action Xiaofei Cheng, Yongxue Wang, and Guoyu Wang Journal of Waterway, Port, Coastal, and Ocean Engineering doi:http://dx.doi.org/10.1061/(ASCE)WW.1943-5460.0000144 Posted ahead of print 20 December 2011 Full Text: \| Download PDF
	+ -	Show Abstract Experiments on a large pipeline and a small pipeline in a piggyback configuration under regular and irregular waves are carried out. A comparison of wave forces on the large pipeline and the small pipeline is made. Non‐dimensional force coefficients for drag, inertia, and lift are obtained based on the Morison equation. The effects of the KC number and the spacing ratio between the two pipelines on the force coefficients for the large pipeline, the small pipeline, and the piggyback pipeline system are investigated. The experimental results indicate that the variation tendencies of drag coefficients and inertia coefficients with the KC number or the spacing ratio for the large pipeline, the small pipeline, and the piggyback pipeline system are similar. The variation tendency of lift coefficient with the spacing ratio for the large pipeline is opposite to that for the small one.

Select this Article		A Fully Nonlinear Model for Water Wave Propagation from Deep to Shallow Waters A. Galan, G. Simarro, A. Orfila, J. Simarro, and P. L. ‐F. Liu Journal of Waterway, Port, Coastal, and Ocean Engineering doi:http://dx.doi.org/10.1061/(ASCE)WW.1943-5460.0000143 Posted ahead of print 7 December 2011 Full Text: \| Download PDF
	+ -	Show Abstract A set of fully nonlinear Boussinessq‐type equations (BTEs) with improved linear and nonlinear dispersive performance is presented. The equations are so that the highest order of the derivatives is three and they use the minimum number of unknowns: the free surface elevation and the horizontal velocity at a certain depth. The equations allow to reduce the errors both in linear frequency dispersion and shoaling below 0:30% for kh ⩽ 5, and below 2:2% for kh ⩽ 10, being k the wave number and h the water depth. The weakly nonlinear performance is also improved for kh ⩽ 2. A simple fourth order explicit numerical scheme is presented so as to test the linear and nonlinear behavior of the model equations against analytical and experimental results.

Select this Article		How the Failure to Account for Flexibility in the Economic Analysis of Flood Risk and Coastal Management Strategies Can Result in Maladaptive Decisions B. Gersonius, T. Morselt, L. van Nieuwenhuijzen, R. Ashley, and C. Zevenbergen Journal of Waterway, Port, Coastal, and Ocean Engineering doi:http://dx.doi.org/10.1061/(ASCE)WW.1943-5460.0000142 Posted ahead of print 1 December 2011 Full Text: \| Download PDF
	+ -	Show Abstract This paper uses two alternative economic analysis approaches, Net Present Value (NPV) and Real In Options (RIO), to show how the failure to incorporate uncertainty and flexibility in the economic analysis of flood risk and coastal management strategies can result in maladaptive decisions. RIO offers a major development on the conventional NPV approach, because it integrates expected changes in future levels of uncertainty into economic analysis. We have applied RIO analysis to the semi‐hypothetical case study of a coastal defence system in order to demonstrate its applicability for decision making on climate change adaptation. In the case study, two different adaptive strategies are analysed, consisting of a hard and soft structural alternative. Soft strategies are often inherently more flexible than hard strategies. The results of the case study show that the NPV approach increases the relative cost of soft strategies for the two alternatives compared with hard strategies, since it does not account for the value of flexibility built into adaptive strategies. We therefore recommend the use of RIO analysis for the choice between hard and soft strategies in order to avoid maladaptation. This is particularly significant in cases where there is both high climate uncertainty and high decision uncertainty concerning the best strategy.

Select this Article		Waves Plus Currents Crossing at a Right Angle: The Sandpit Case Carla Faraci, Enrico Foti, Alberto Marini, and Pietro Scandura Journal of Waterway, Port, Coastal, and Ocean Engineering doi:http://dx.doi.org/10.1061/(ASCE)WW.1943-5460.0000140 Posted ahead of print 1 December 2011 Full Text: \| Download PDF
	+ -	Show Abstract The present paper explores the possibility to exploit sandpits at intermediate and shallow water depths, by analyzing both the hydrodynamic and the morphodynamic response in the proximity of a dredged area. More precisely, a laboratory investigation was carried out to analyze the effects of wave ‐ current interaction over a borrow area, particularly in terms of morphodynamic evolution of the pit. The influence of both regular and irregular waves on the current was analysed. It was found that the flow is significantly influenced by such interaction in the presence of the borrow area. The morphodynamic evolution of the sandpit is mainly affected by the waves, while the superimposition of a current does not introduce qualitative modifications but increases the mobilization of sediments, with repercussions on the speed of the evolution process. The results of the experimental campaign suggested that the analysis of the morphodynamic evolution can be approached at a laboratory scale. Indeed, the volume infill rate resulted in agreement with observations in real dredged sites (CNEXO pit); moreover the same quantity can be interpreted in the light of literature relations proposed to describe time evolution of non‐cohesive sandy beds.

Select this Article		Onshore Migration of Emerged Ridge and Ponded Runnel Jens Figlus, Nobuhisa Kobayashi, M. ASCE, and Christine Gralher Journal of Waterway, Port, Coastal, and Ocean Engineering doi:http://dx.doi.org/10.1061/(ASCE)WW.1943-5460.0000139 Posted ahead of print 12 November 2011 Full Text: \| Download PDF
	+ -	Show Abstract Ridge‐runnel features can comprise large volumes of sand and their migration can have a significant influence on the coastal sediment budget and beach recovery after a storm. Numerical modeling of ridge‐runnel migration is challenging partly because of the strong interactions between the hydrodynamics and morphology and partly because of limited available field and laboratory measurements. We conducted an experiment in a sand flume where detailed free surface and velocity measurements were taken in the ponded water zone of the runnel and in the intermittently wet and dry zone on the ridge crest to investigate the effect of water ponding and runnel drainage on onshore ridge migration. The test scenario with a drained runnel showed a ridge migration speed five times larger than the scenario where water and sediment could only exit the runnel as offshore return flow over the ridge. The time‐averaged numerical model CSHORE was modified to include the ponded water effect in the sediment transport formulations. Results show the capabilities and shortcomings of CSHORE in reproducing the hydrodynamics, morphological evolution, and sediment transport rates measured during the experiment.

Select this Article		Shear Stress Measurements and Erosion Implications for Wave and Combined Wave‐Current Generated Flows Richard A. Jepsen, Jesse D. Roberts, Sean P. Kearney, Thomas G. Dimiduk, Timothy J. O'Hern, and Joseph Z. Gailani Journal of Waterway, Port, Coastal, and Ocean Engineering doi:http://dx.doi.org/10.1061/(ASCE)WW.1943-5460.0000137 Posted ahead of print 3 November 2011 Full Text: \| Download PDF
	+ -	Show Abstract Sediment transport in wave dominated environments is of great interest for dredged material placement, contaminated sediments, habitat protection, and other issues. The shear stress at the sediment‐water interface during a wave event is an important parameter in determining erosion and transport for both experimental and model simulation applications. Sandia National Laboratories has developed a laboratory and field device called the SEAWOLF flume in which high resolution Particle‐Image Velocimetry (PIV) has been applied to investigate turbulent flow shear stresses for a variety of flow conditions. The results of the PIV analysis for a wave cycle demonstrate a fully developed turbulent flow, relaminarization, and an explosive transition back to turbulence. In many cases, the results for the flume tests did not show good agreement with previously reported CFD results and existing theory such as Blasius for wave‐current interactions which raises the question of whether similar phenomena are present in real environments. These results implore more study to be conducted with similarly high resolution field measurements and modeling efforts to determine shear stress time history for oscillatory flows and the subsequent effects on erosion and sediment transport in wave dominated environments.

Select this Article		Resonances in an Evolving Hole in the Swash Zone Steve Elgar, Britt Raubenheimer, Jim Thomson, and Melissa Moulton Journal of Waterway, Port, Coastal, and Ocean Engineering doi:http://dx.doi.org/10.1061/(ASCE)WW.1943-5460.0000136 Posted ahead of print 3 November 2011 Full Text: \| Download PDF
	+ -	Show Abstract Water oscillations observed in a 10‐m diameter, 2‐m deep hole excavated on the foreshore just above the low‐tide line on an ocean beach are consistent with theory. When swashes first filled the initially circular hole on the rising tide, the dominant mode observed in the cross‐shore velocity was consistent with a zero‐order Bessel function solution (sloshing back and forth). As the tide rose and swash transported sediment, the hole diameter decreased, the water depth inside the hole remained approximately constant, and the frequency of the sloshing mode increased according to theory. About an hour after the swashes first reached the hole, it had evolved from a closed circle to a semi‐circle, open to the ocean. When the hole was nearly semi‐circular, the observed cross‐shore velocity had two spectral peaks, one associated with the sloshing of a closed circle, the other associated with a quarter‐wavelength mode in an open semi‐circle, both consistent with theory. As the hole evolved further toward a fully semi‐circular shape, the circular sloshing mode decreased, while the quarter‐wavelength mode became dominant.

Select this Article		Numerical Analysis of the Dynamic Response of an Offshore Platform with a Pile‐Soil Foundation System Subjected to Random Waves and Currents Min‐Su Park, Weoncheol Koo, and Kenji Kawano Journal of Waterway, Port, Coastal, and Ocean Engineering doi:http://dx.doi.org/10.1061/(ASCE)WW.1943-5460.0000133 Posted ahead of print 7 October 2011 Full Text: \| Download PDF
	+ -	Show Abstract In this study, a three‐dimensional numerical model was developed based on a modal analysis and substructure method. The devised model was employed for an evaluation of the dynamic response of a bottommounted platform with a pile‐soil foundation system that was subjected to random waves and currents. A 2D numerical scheme with the Newmark β method was extended to three dimensions. The equation of motion was solved by using cylindrical beam elements to analyze the response of the superstructure, and the impedance function method was employed to model the pile‐soil foundation system. The displacement and bending stress at selected nodal points of the structure were computed using various input parameters, such as the shear‐wave velocity of the soil and the mean wave height and period. The effect of the current on the structural response was also evaluated. Using the reliability index obtained from the Monte Carlo simulation method, the reliability of the dynamic response at critical structural members, which contained uncertainties due to dynamic forces and structural properties, was assessed.

Select this Article		Geometrical Effects on Landslide Generated Tsunamis Valentin Heller, Mahtab Moalemi, Robert D. Kinnear, and Rorik A. Adams Journal of Waterway, Port, Coastal, and Ocean Engineering doi:http://dx.doi.org/10.1061/(ASCE)WW.1943-5460.0000130 Posted ahead of print 3 October 2011 Full Text: \| Download PDF
	+ -	Show Abstract Landslide generated tsunami predictions are commonly based on wave channel (2D) or wave basin (3D) experiments with considerably different outcomes. It is not fully understood which idealised geometry applies best to a specific prototype. Hence, a physical small‐scale model study has been conducted which for the first time systematically investigates the effect of geometry on landslide generated tsunami height, amplitude, period and celerity. A rigid slide generated tsunamis propagating in different geometries characterised by the basin side angle θ. Considered were the 2D (θ = 0°), 3D (θ = 90°) and six intermediate geometries. Differences between wave heights in 2D and 3D are found to be about 20% at a distance of five times the water depth from the slide impact zone, but increase with increasing distance. It is shown that the 3D case applies on a much wider prototype range than 2D since it approximates the wave features on the slide axis for all investigated geometries with θ > 30°. Energy flux conservation based on given 2D results can predict wave heights for the remaining geometries with θ ≤ 30°. The implications of the present results in practice are discussed and an example illustrates how the results support tsunami hazard assessment despite significant scale effects.

Select this Article		Optimized Predictive 2D Hydrodynamic Model of the Gironde Estuary (France) Nicolas Huybrechts, Catherine Villaret, and Florent Lyard Journal of Waterway, Port, Coastal, and Ocean Engineering doi:http://dx.doi.org/10.1061/(ASCE)WW.1943-5460.0000129 Posted ahead of print 29 September 2011 Full Text: \| Download PDF
	+ -	Show Abstract A 2D hydrodynamic model of the macrotidal Gironde estuary (France) is developed and shown to predict the tide propagation with an accuracy of less than 10 cm on water level. The 170 km long computational domain represents in detail the central part of the estuary, characterized by a complex multi‐channel geometry. This model provides an efficient and accurate operational tool thanks to the use of an optimized finite‐element numerical scheme. Particular attention is paid here to the offshore boundary conditions and to the calibration procedure. On the offshore boundary, the tidal signal is decomposed into harmonics whose main amplitudes and phases are obtained from a regional tidal model covering the North East Atlantic. Sensitivity studies are conducted to determine the influence of the harmonics number and harmonic constants on tidal prediction at the mouth. Differences up to 20∼30 cm in water level at the estuary mouth are observed between the scenarios for the tidal forcing. The calibration of the friction coefficient is thus linked to the tidal forcing scenario. A calibration procedure for the friction coefficient is also presented which can be applied to estuarine conditions. The van Rijn method is applied to predict a first set of values for the friction coefficients as a function of grain size and flow parameters. These predicted mean (time‐averaged) coefficients are then adjusted with a maximum of 15 % to reproduce in a best way water level and velocity measurements.