Journal of Waterway, Port, Coastal, and Ocean Engineering

Because of the increasing size and amount of vessels, it is important to efficiently manage vessel scheduling in ports. This study aims to assess the effects of channel and berth resources on the operation efficiency of ports using a multiobjective vessel scheduling optimization model. Using the minimum total scheduling time and the waiting time of the vessels as input, the model is for a one-way channel considering the safety, efficiency, and fairness of the scheduling. To solve the scheduling problem, the multiobjective genetic algorithm (MOGA) was used. A scheduling trial for 20 vessels at certain peak hours at a port is simulated. The MOGA simulation obtained eight Pareto optimal solutions, which are vessel scheduling schemes. Compared with the first-come, first-served (FCFS) scheduling method, the capacity conversion times of vessels inbound and outbound can be reduced ninefold, and the total scheduling time can be reduced by more than 40%.

In this study, a high-resolution, two-dimensional (2D), time-dependent hydrodynamic model of the St. Lawrence fluvial estuary was developed with the objective of documenting the tidal hydrodynamics of this complex yet poorly understood region. The hydrodynamic model solves the shallow-water equations over a finite-element–discretized domain, with an average spatial resolution of 50 m, and includes a drying–wetting component for the treatment of shallow intertidal areas. The numerical terrain model is composed of high-density topographic data and detailed friction fields associated with bottom substrate and macrophytes. Calibration and validation were carried out using recently acquired data for water level and velocity. Results show very good accuracy in water levels, with prediction skills higher than 0.99 at all stations (where a skill of 1 means perfect agreement between model and observations in terms of their relative average error) and root-mean-square errors (RMSEs) less than 5% of local tidal ranges downstream; at upstream stations where tidal ranges are significantly reduced, RMSEs were lower than 6 cm. Discharges were reproduced with similarly good accuracy, with errors lower than 6% of the maximum observed discharges at 11 of the 13 surveyed transects; the two remaining sections are subject to larger interpolation and bathymetric uncertainties. In this paper, critical aspects of model development are discussed, including the 2D approximation, temporal and spatial resolution, bathymetric uncertainty, error in the boundary conditions, and calibration under nonstationary conditions. This work is the first part of a two-part investigation serving as a methodological framework for model setup, calibration, and validation in large tidal rivers.

This is the second part of an investigation aimed at documenting the tidal hydrodynamics of the St. Lawrence fluvial estuary (SLFE). In Part I, the calibration and validation of a high-resolution, two-dimensional (2D), time-dependent hydrodynamic model of the SLFE was presented. Herein, the process-based (structural) validation procedure used to quantitatively assess the ability of the model to reproduce spatial and temporal patterns observed in the field data is presented. Tidal and flow features were found to be reproduced satisfactorily in terms of their lateral and longitudinal variability at both the intratidal and fortnightly scales. These properties can be used to describe the real system dynamics, including flooding–drying processes, tidal propagation and modulation, and transient momentum balance, providing insights into the general physical processes of the SLFE and of large tidal rivers globally.

This laboratory study investigated the sedimentation behavior of a fly ash–based geopolymer-stabilized dredged-mud slurry extracted from the Port of Townsville, Queensland, Australia. Settling-column tests were conducted to study the sedimentation behavior of 400%-water-content dredged mud of untreated and geopolymer-stabilized slurries at 6, 12, and 18% content by weight. Dredged-mud slurry interface height movements with elapsed time were recorded, and their settling patterns were observed. Mineralogical and microstructural characteristics of dried, untreated, and geopolymer-stabilized dredged-mud sediments were determined using X-ray diffraction (XRD) and scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) analysis. The study found that a fly ash–based geopolymer gel coating the dredged-mud particles in the slurry led to a flocculated settling behavior, and the geopolymer stabilization reduced the overall dredged-mud slurry sedimentation duration. XRD and SEM/EDS analysis showed that the geopolymer stabilization altered the microstructure of stabilized dredged-mud sediment and reduced its desiccation shrinkage cracks.

Twin propellers without a rudder were studied using a physical model with a fixed clearance distance and three different rotating velocities. Experimental results were compared with results from theoretical expressions developed over the past 50 years for the efflux velocity, axial velocity, and maximum bed velocity. It was found that the efflux velocity equations overestimated the experimental results, whereas the computed axial velocities matched the experimental data reasonably well. However, when maximum bed velocity expressions were compared with experimental results, only one method was found to behave better; overestimation resulted if a quadratic superposition of single jets was used.

This paper applies a simple energy method to predict characteristics of overland tsunami flows based on extrapolation of the energy grade line between the shoreline and the tsunami run-up limit. Starting with a mapped run-up or inundation limit from tsunami hazard maps or from field surveys, the method reconstructs maximum inundation depths and velocities across a flooded topographic transect to the shoreline. The energy method is evaluated first in comparison with thousands of numerical simulations conducted on idealized topographies using a free-surface wave model. The method is then evaluated in more detailed simulations over realistic topography using a second tsunami-evolution model. Finally, the method is evaluated against field observations of inundation depths from tsunami events in Chile and Japan. In all cases, inundation depths are predicted quite well, with little bias across a wide range of flow conditions and topographic conditions. Predicted velocities show less precision but seem to predict the general velocity decay from shoreline to run-up limit. The method then overestimates and provides a conservative estimate of the maximum momentum flux.

Permeable and slender coastal protection systems are gaining ground in the field because they are relatively economical and easy to construct compared to traditional-type breakwaters. In this study, a breakwater consisting of prefabricated rectangular cells with two vertical permeable walls supported by two rows of vertical circular piles was proposed. The vertical wall consisted of a perforated upper part and a lower part with horizontal slots. The number of cells varied depending upon water depth. The wave transmission, reflection, and energy dissipation characteristics of the breakwater under regular waves for a normal angle of incidence were studied experimentally and analytically. The hydrodynamic characteristics of the proposed breakwater were investigated for different wave conditions and different structural parameters. Studies were carried out for different values of relative upper-part submergence from a still water level (SWL) and also by varying the porosity of the upper portion and the relative spacing between the walls. An eigenfunction expansion method was used to develop the analytical model to study the hydrodynamic performance of the breakwater. The results reveal that a reasonable agreement was obtained between the experimental and analytical models; however, in some cases, the analytical model slightly underestimated the hydrodynamic characteristics by no more than 10%.

The present work is a numerical investigation into the waves generated by a pressure source moving in straight channels with a nonrectangular cross-channel depth profile. Wave fields generated by the moving pressure source are described, and the effects of channel bathymetry on the generated wave characteristics of wave height, wave-breaking location, wave-breaking type and intensity, and peel angle are presented. Four different channel cross-section shapes were investigated, and the results were analyzed. It was concluded that the maximum wave height depended primarily on pressure-source parameters and that the investigated channel shapes did not have a significant effect on the maximum wave height. All four investigated channels were able to generate plunging-shaped breaking waves. In addition, wave-breaking intensity and barrel shape could be controlled by beach-slope shape; however, beach slope did not have a considerable effect on the wave-breaking location. The width of the deep section of the channel had a significant effect on the breaking location. Widening the deep section of the channel moved the breaking point farther from the pressure source. According to the simulation results, it is possible to generate waves for an intermediate or expert surfer only by changing the pressure-source speed. According to the results, by changing the pressure-source speed, the peel angle changes, which is the best way to change the required skill level for surfing. In addition, changing the channel shape did not have a significant effect on the required skill level for surfing.

Offshore gravity base foundations (GBFs) are often designed with complex geometries. Such structures interact with local hydrodynamics, creating an adverse pressure gradient that is responsible for flow and scour phenomena, including the bed shear stress amplification. In this study, a method is presented for predicting clear-water scour around cylindrical structures with nonuniform geometries under the force of a unidirectional current. The interaction of the flow field with the sediment around these complex structures is described in terms of nondimensional parameters that characterize the similitude of water-sediment movement. The paper presents insights into the influence the streamwise depth-averaged Euler number has on the equilibrium scour around uniform and nonuniform cylindrical structures. Here, the Euler number is based on the depth-averaged streamwise pressure gradient (calculated using potential flow theory), the mean flow velocity, and the fluid density. Following a dimensional analysis, the controlling parameters were found to be the Euler number, pile Reynolds number, Froude number, sediment mobility number, and nondimensional flow depth. Based on this finding, a new scour-prediction equation was developed. This new method shows good agreement with the database of scour depths acquired in this study $(R^2=0.91)$. Measurements of the equilibrium scour depth around nonuniform cylindrical structures were used to show the importance of the Euler number in the scour process. Finally, the importance of the remaining nondimensional quantities with respect to scour was also investigated in this study.

A plethora of studies in the last decade described tsunami hazards and studied their evolution from the source to the target coastline but mainly focused on coastal inundation and maximum run-up. Nonetheless, anecdotal reports from eyewitnesses, photographs, and videos suggest counterintuitive flow dynamics, for example, rapid initial acceleration when the wave first strikes the initial shoreline. Further, the details of the flow field at or within tens of meters of the shoreline are exquisitely important in determining damage to structures and evacuation times. Based on a set of three-dimensional Lagrangian numerical simulations, the authors used a model to simulate solitary waves and analyze the spatiotemporal distribution of the potential energy, kinetic energy, and momentum flux during the breaking process. The wavefront accelerates when in the proximity of the shoreline due to the change in slope of wave path; hence, it is the most dangerous part of the tsunami at any time regardless of the H/d₀ wave ratio. The authors inferred that the highest destructive capacity of flow occurs when momentum flux reaches its maximum, and this takes place in the initial shoreline environment. This maximum coincides with the local maxima of the potential and kinetic energy, making the shoreline prone to the most turbulent and dangerous flow, during the breaking and inundation processes. Therefore, momentum flux is a more important variable, over and above potential and kinetic energy, to be considered in tsunami-hazard and mitigation evaluations as well as in nearshore structure design.

Port capacity is an essential parameter for the assessment of port performance. In the literature, there is no unanimous capacity definition, which depends on each research goal. Vessel traffic in ports and the corresponding port performance indicators have been analyzed with different simulation models, but they generally do not include a method for determining a port’s capacity. Guidelines or other studies using empirical data also have not addressed this important topic. The method developed in this paper estimates the port network traffic capacity (PNTC) by using vessel traffic data. The analysis and comparison of several indicators are used to identify meaningful relationships for estimating port capacity with generic applicability to any port design. The relation between the total number of trips in the port and the ratio of waiting time to service time seems to be the most suitable for identifying when the port reaches unstable flow situations, that is, when it reaches capacity. The method has been applied successfully in six scenarios with various berths, layouts, service times, vessel fleet types, and maneuvering times. Application of the method is useful during the port-planning phase, because with a few simulations, an indicative PNTC value for each design can be inferred, and thus, different scenarios can be compared.

Wave energy is a renewable energy source that has an immense potential for exploitation as clean energy. Studies on the oscillating water column (OWC) widely pertain to the optimization of its geometries to enhance the wave power absorption; comparatively, the wave-induced loadings on such structures have received lesser attention. Hence, in this study, a detailed experimental investigation was undertaken to investigate the nature and magnitude of the dynamic pressures exerted on different components of the OWC and the total force on the structure subjected to regular wave incidence. In general, the forces were found to increase with wave steepness. In the structural design of the lip wall of the OWC, the seaward exerted pressure also should be considered as a critical parameter because it governs the stability toward the seaside. The total horizontal wave force was noted to be 2.5 to 3 times greater than the total vertical wave force. A comparison of the measured force with results from a standard formula for wave force estimation on vertical wall revealed that the formula overestimated the shoreward force and underestimated the seaward force in the low-frequency zone.

The hydrodynamic behavior of a rectangular pile-moored floating breakwater with 1 degree of freedom (DOF) is simulated using a weakly compressible smoothed particle hydrodynamic (WCSPH) scheme. The wave–structure interaction and related hydrodynamic forces were evaluated by solving a modified smoothed particle hydrodynamic–based equation derived to consider the boundary motions. In the modified equation, the effects of acceleration of fluid/solid particles were considered. To investigate the efficiency of the developed numerical model, two verification tests were performed on a square and a rectangular floating body with 3 DOFs (heave, sway, and roll motions), and the results were compared with available experimental data. Moreover, for simulating the hydrodynamic behavior of pile-moored floating breakwater, two test cases with different conditions were investigated. The hydrodynamic behavior of a typical floating breakwater and breakwater transmission, reflection coefficients, and dynamic response in heave motion were evaluated for different water-depth conditions and three draft values of the structure. The obtained results reveal that the proposed modifications in the boundary treatment can improve the accuracy of fluid–structure interaction in numerical models on the basis of the smoothed particle hydrodynamic scheme.

Despite the progress in scour research over the last three decades, seabed scour development in cohesive and nonuniform soils is still an area of great uncertainty and remains a challenge for designing structurally efficient and effective foundations in the offshore marine environment. The uncertainty is made greater by the timescale required for scouring and effects, such as sediment abrasion, pile installation impacts, and operationally and environmentally induced dynamic motions. The rapid growth in offshore wind, particularly in European waters, has led to a requirement for estimates for scour development in such soils. This becomes very pertinent for large-volume serial installation of foundations, such as those required for offshore wind farm developments, given that there is a limit to the amount of detailed geotechnical information that can be collected as part of a project, and soil erosion testing is not standard. There is a reliance in geotechnical data, such as undrained shear strength, derived from cone penetration tests, supplemented with borehole data collected at a limited number of locations across the wind farm site combined with laboratory analysis of soil samples. This paper reviews the present evidence from both field and laboratory measurements of scour potential and looks at possible approaches for determining scour magnitude in cohesive soils including hydraulic and mechanical effects.

Geocontainers have been increasingly used in various estuarine and coastal engineering projects. However, it is difficult to determine the horizontal settling distances of geocontainers when they are dumped into deep water. Three new types of geocontainers were proposed on the basis of a unitary geocontainer. Type-selection and parameter-screening experiments were conducted in a flume to determine the optimal type of geocontainer and its optimal parameter combination. Based on the optimal parameter combination, a regularity experiment was conducted under 25 different water depth and flow velocity conditions to determine the settling mechanism of the optimal type of geocontainer. Last, empirical formulas were proposed for evaluating the drag and lift coefficients, and the horizontal settling trajectories of the optimal type of geocontainer were calculated. The results of these experiments confirm the ternary-type geocontainer as the optimal type of geocontainer, and the standard deviation of the settling distances was smallest when the dimensions were D × B = 16  × 12 cm. The filling ratio φ was 78.54%, the sliding distance L was 5 cm, and the bevel angle α was 40°.

A simple analytical model for a small bay with a tidal inlet channel was developed to predict the peak still-water elevation in the bay for the specific peak still-water elevation and surge duration in the ocean. The model was applied to the Delaware Atlantic coast where three bay-tide gauges, together with one ocean-tide gauge, have been in operation since 2005. Twenty-seven storms identified between 2005 and 2015 were used to calibrate a dimensionless parameter related to inlet and bay characteristics. The calibrated model predicted the peak still-water elevation within 10% error at two bay gauges and within 30% error at the third bay gauge. Wave overtopping and overwash over the barrier beach between the ocean and bay occurred during Hurricane Sandy in 2012. Wave overtopping and barrier beach evolution were predicted using a cross-shore numerical model. The analytical model including wave overtopping predicted the peak still-water elevation increase of 0.1–0.2 m (10–20%) in the bay. The coupled approach is useful in evaluating bay-flooding risk for given storm statistics for the ocean.

Barrier island overwash and breaching are caused by inundation from ocean storm surge and waves or from elevated levels of bay water. According to numerical simulations, a developed barrier island in New Jersey experienced major overwash and some breaching during Hurricane Sandy in 2012 as a result of an extreme rise in bay surge within Barnegat Bay 6 h after peak ocean surge. In this study, a sensitivity analysis was conducted on the effects of peak bay-surge timing and magnitude on the morphological change in the presence and absence of a seawall. Results from the numerical model indicate that the timing of the peak bay surge in the northern portion of Barnegat Bay was a major contributor to the damage observed at nearby locations along the barrier island. By shifting bay-surge timing, island erosion was reduced up to 130%, mostly on the back barrier, the location of the majority of coastal infrastructure. Additionally, simulations show that a seawall protected the island from severe erosion by preventing ocean and bay surge from flowing freely across the island. In the absence of a seawall, the elevation of the island was significantly eroded under Hurricane Sandy conditions, where erosion was exacerbated by increases in bay-surge magnitude.

The U.S. Army Corps of Engineers (USACE) recently completed a detailed study to address the coastal storm and flood risk to vulnerable population, property, ecosystems, and infrastructure affected by Hurricane Sandy. One component of the North Atlantic Coast Comprehensive Study (NACCS) used a suite of high-fidelity numerical models to produce nearshore water level and wave estimates for the North Atlantic coast. Nearshore wave transformation for the NACCS was accomplished using the wave model Steady-State Spectral Wave (STWAVE). To represent rigorously the underlying physical processes of the modeled storm events, tight two-way coupling between an advanced circulation model and STWAVE was facilitated with a modeling system for coastal storms. Seven historical storm events, two extratropical and five tropical storms, were selected for evaluation of the STWAVE model. The storms selected were Hurricane Gloria (1985), extratropical 070 (January 1996), extratropical 073 (December 1996), Tropical Storm Josephine (1996), Hurricane Isabel (2003), Hurricane Irene (2011), and Hurricane Sandy (2012). Mining numerous data sources identified 30 buoys within the STWAVE domain. STWAVE results were compared to the existing measurements using both graphical and statistical methods, resulting in one of the most comprehensive nearshore wave model assessments to date. The performance of STWAVE improved significantly with more recent storms, particularly for Irene and Sandy. This improvement is likely the result of a combination of factors, such as, but not limited to, more accurate wind and offshore forcing, advancements in buoy technology, and a large measurement population.

Regional-scale and local damage surveys of the U.S. Mid-Atlantic coast were performed after Hurricane Sandy in 2012. A satellite-based analysis of over 15,000 houses within one block of the New Jersey, Long Island, and Staten Island coastlines showed a strong correlation between destruction and poststorm dune heights. A detailed survey in Ocean County, New Jersey, classified 380 homes into seven damage states to different subassemblies. A phase-resolving Boussinesq-Green-Naghdi wave model simulating the strongest hour of the storm was used to evaluate hydrodynamics at each residence. Maximum computed water surface elevations were found to differ strongly from standard depth-limited assumptions. A vulnerability model to diagnose the damage state of a coastal residence subject to storm conditions identified maximum water velocity and relative shielding as critical predictors of damage. Improved hydrodynamic models that can efficiently compute the complex flow interactions with structures may provide more reliable damage prediction in coastal communities.

An asymptotic approach to the linear problem of regular water waves interacting with a vertical cylinder of an arbitrary cross section is presented. The incident regular wave was one-dimensional, water was of finite depth, and the rigid cylinder extended from the bottom to the water surface. The nondimensional maximum deviation of the cylinder cross section from a circular one plays the role of a small parameter of the problem. A fifth-order asymptotic solution of the problem was obtained. The problems at each order were solved by the Fourier method. It is shown that the first-order velocity potential is a linear function of the Fourier coefficients of the shape function of the cylinder, the second-order velocity potential is a quadratic function of these coefficients, and so on. The hydrodynamic forces acting on the cylinder and the water surface elevations on the cylinder are presented. The present asymptotic results show good agreement with numerical and experimental results of previous investigations. Long-wave approximation of the hydrodynamic forces was derived and used for validation of the asymptotic solutions. The obtained values of the forces are exact in the limit of zero wave numbers within the linear wave theory. An advantage of the present approach compared with the numerical solution of the problem by an integral equation method is that it provides the forces and the diffracted wave field in terms of the coefficients of the Fourier series of the deviation of the cylinder shape from the circular one. The resulting asymptotic formula can be used for optimization of the cylinder shape in terms of the wave loads and diffracted wave fields.

This study investigates the performances of theoretical wave attenuation models in predicting vegetation-induced wave decay. The existing theoretical models are all based on linear wave theory, which cannot describe nonlinear waves accurately. This study applies Stokes second-order and cnoidal wave theories to solve the energy balance equation for wave height evolution. Results from a phase-resolving numerical model serve as reference solutions. A total of 30 tests are devised for shallow-intermediate water waves through emergent and submerged vegetation. The differences between theoretical and numerical model results (ϵ_H) and between linear and nonlinear-based theoretical model results (ΔH) are quantified. The test results show that for wave propagation through emergent vegetation ΔH is ≤6% and ϵ_H is ≤5%, whereas over submerged vegetation, ϵ_H reaches as large as 25%. With a 5% tolerance of ϵ_H, linear-based theoretical models remain valid for emergent cases and submerged cases with a small Ursell number (≤30 in this study). This work has found that the inability of theoretical models to simulate the in-canopy velocity reduction and nonlinear wave-wave triad interactions contributes to the large ϵ_H in submerged cases.

Measured time series of the sediment volume of dredging and disposal areas in the Scheldt estuary of the Netherlands and Belgium are presented and compared to an equilibrium-type response model. The model is based on the assumption that the sediment volume removed from a dredging area returns through siltation at a rate proportional to the difference between the current sediment volume and a time-dependent autonomous equilibrium volume. For disposal sites, a similar assumption is made regarding the rate at which the dumped sediment disappears through erosion. The model contains three fitting parameters for disposal areas or two parameters for dredging areas and was fitted to observed sediment volume time series of five disposal sites and eight dredging areas in the Scheldt estuary, for which frequent bathymetric surveys were conducted as part of the flexible disposal management plan. Model results indicate that sediment dumped in disposal areas has a half-life residence time of 179–409 days, and dredging areas show shorter response times of 0–187 days. Results also show that, following a disposal event, the observed sediment volume on the bed is typically smaller than what is estimated based on hopper volumes. The model can also be used to forecast future sediment volumes as a result of planned dredging or disposal campaigns and thus can serve as a decision-making tool for estuary managers.

The focus of this paper is on the storm surge modeling effort conducted as part of the North Atlantic Coast Comprehensive Study (NACCS). At the time of this study, the numerical modeling component of the NACCS was the largest civil works high-performance computational modeling effort conducted by the U.S. Army Corps of Engineers (USACE), requiring approximately 100 million CPU hours to complete. The NACCS modeling effort involved the application of the latest atmospheric, wave, and storm surge models and extreme value statistical analysis techniques. The methodology for computing winds, waves, and water levels involved the application of a suite of high-fidelity numerical models within the Coastal Storm Modeling System (CSTORM-MS), including an offshore wave model, WAM, and a nearshore wave model, STWAVE, coupled with the circulation and storm surge model ADCIRC. The high-fidelity modeling suite applied to the NACCS study required extensive grid development, implementation of bathymetric and topographic data, surge and wave model coupling and, because of the magnitude of the study, production script development for automation of model input development, execution, postprocessing, and archiving of model results. The ADCIRC model developed for this study included approximately 6.2 million computational elements and 3.1 million computational nodes, with ADCIRC mesh resolution concentrated in the approximately 1,450-km region from Virginia to Maine. In addition, 10 STWAVE model domains covered the nearshore zone from Virginia to Maine. The WAM model applied to the NACCS required three levels of refinement to adequately simulate offshore waves for this study. Prior to starting NACCS production simulations, the numerical models were validated for a set of historical tropical and extratropical storm events. Production model simulations (consisting of both synthetic and historical storms) were performed during an 8-month period, analyzed, and ultimately incorporated into the Coastal Hazards System (CHS). (The synthetic tropical storms were developed to populate the statistical parameter space as part of the project design process.) The suite of storms included 1,050 synthetic tropical storms and 100 historical extratropical events, each simulated for four conditions. Production storms were first simulated as surge only simulations with the application of ADCIRC in stand-alone mode and were then simulated as surge plus wave simulations by applying the CSTORM-MS to include the effect of wave radiation stress gradients on water levels. Next, the 1,150 surge plus wave storm suite was repeated with the inclusion of either a random tide (synthetic tropical storms) or a historical tide (historical extratropical events). Last, the surge plus wave and tide storm suite was simulated with the inclusion of a 1.0-m increase in sea-level adjustment. The storage requirement for the 4,600 NACCS production simulations and other project files was approximately 190 TB. This paper primarily focuses on the ADCIRC model development and validation, whereas other studies focus on other processes, such as the extreme value statistical analysis techniques and the characterization of storm surge response to the inclusion of waves, tide, sea-level change, and variation in storm forcing parameters.

A method is developed to estimate harbor seiche at Marina di Carrara, Italy, from the properties of wind-generated incident waves outside the harbor. A linear model of the spatial structure of amplified seiche modes is combined with empirical estimates of the response of each mode to variable incident wave forcing. These empirical coefficients parameterize the complex nonlinear transfer of energy from wind waves to lower frequency seiche. As at other small harbors (<1 km² surface area) on ocean coasts, and consistent with previous analyses at Carrara, the observed seiche is relatively energetic at several periods between about 1 and 15 min that are highly amplified theoretically, and the spatial structure of modeled and observed seiches agree as well. The longest seiche (≈15 min) mode is almost spatially uniform within the harbor and dominates with low-energy, short-period incident wind waves (measured 1 km offshore of the harbor). Increased wave energy and longer periods excite shorter period (1–3 min) seiche modes with more complex spatial structure, including small areas of high amplification, which have led to operational issues. The energy in each of the six most energetic seiche modes is related in this paper empirically to offshore incident wind wave height and peak period, allowing detailed predictions of harbor seiche from routine wind wave forecasts. The approach appears applicable to relatively small, shallow harbors with reflective quay walls, in which the exterior harbor mouth is exposed, and the interior sheltered from energetic wind-generated waves.

For Galveston Bay and much of the Upper Texas Gulf Coast, the havoc imparted by the hurricanes of 1900 and 1915, in addition to Hurricane Ike of 2008, served to expose the growing and unmitigated flood risks for the surrounding local communities, ecosystems, and economies. Previous studies have proposed methods for regional storm surge protection but have emphasized either (1) localized protection for specific areas or (2) shortening of the coastline with structural barrier systems placed across major tidal inlets and barrier islands. In this study, a new storm surge reduction strategy—the Mid-Bay Strategy (MBS)—was developed that incorporates functional elements from each approach and takes advantage of existing dredged material and disposal sites adjacent to the Houston Ship Channel (HSC) near the middle of Galveston Bay (i.e., the Mid-Bay). The MBS consists of a set of interacting components that includes the beneficial use of dredged material, wetland restoration, elevated roadways, and a primary gate structure across the navigable HSC within Galveston Bay. The final design and implementation of such components will likely depend on the availability of federal, state, and local funding sources, thereby influencing the final design-build costs, scheduling, and constructability. The objective of this study was to provide a planning-level assessment of the hydrodynamic performance of the MBS under two phases of constructed implementation using a coupled hydrodynamic computational model. A suite of hurricane events, including historical, pseudosynthetic, and fully synthetic events, was used to evaluate the dredged MBS berm heights for each phase of construction. In Phases 1 and 2, the optimal berm heights for storm surge reduction were identified as 7.3 m (24 ft) and 6.1 m (20 ft), respectively, for a specific proxy storm. The maximum storm surge reduction ranged from 4.57 m (15 ft) to 5.33 m (17.5 ft) for west and north Galveston Bay, respectively, for Phases 1 and 2. Additional hurricanes were simulated to analyze the MBS’s optimized level of effective protection. Overall, the results show that the MBS was able to provide sufficient storm surge protection for all storms within the evaluation suite. In addition, this work highlights the importance of selecting appropriate proxy storms for achieving reliable and rapid assessments of the performance of conceptual storm surge protection strategies.

The large-diameter driven pile is one of the most common types of foundations used for offshore structures. Field tests of two offshore driven piles, each with a diameter of 2.2 m, subjected to lateral monotonic and cyclic loads in soft clay, were carried out at the Guishan Offshore Wind Farms in the Guangdong Province of China. Further analysis of the test results showed that the initial stiffness and ultimate soil reaction per unit length of the derived p-y curves of the driven piles were obviously larger than those of the American Petroleum Institute (API) p-y curves for the investigated soft clay soil. This finding could be a result of reconsolidation of soil around the pile after it was driven. The computed modified hyperbolic tangent p-y curves were in good agreement with the test results. For one-way cyclic loading tests, a cyclic degradation factor, t, was defined and calculated on the basis of the derived cyclic p-y curves, which were approximately linear to the cyclic soil reaction ratio and decreased as the soil depth increased. The factor t can be used to analyze the lateral cyclic responses of offshore driven piles, and the experimental results can provide valuable reference for analyses of lateral monotonic and cyclic pile–soil interactions in soft clay.