Journal of Waterway, Port, Coastal, and Ocean Engineering

The design of marine structures requires the simulation of wave parameters that consider sea-state and water-depth transitions. Proper selection of the model coefficients (e.g., alpha and gamma of the JONSWAP spectra) is then required, because of the wave-hydrodynamic nonlinearities during these ocean processes. Therefore, the model coefficient selection should be tested using a nonlinear analysis to assess the effect of the selected spectra coefficients over the modeled wave parameters. The present study performed a design of experiment (DOE)-analysis of variance (ANOVA) and probability analysis to assess the effect of alpha and gamma parameters over the significant wave height (Hs) and peak period (Tp) during sea-state and water-depth transitions. The DOE-ANOVA demonstrated for the mean and extreme wave states of the study area that alpha and gamma parameters positively affect the Hs behavior in deep and intermediate waters. Furthermore, the standardized effects of alpha and gamma over the Tp during extreme wave states suggest quadruplets of wave–wave interactions. The joint and normal probability distributions of alpha and gamma for extreme and normal waves showed a Gaussian distribution, allowing identification of specific alpha and gamma values for the JONSWAP spectra model. The selected alpha and gamma parameters were then validated through the comparison of the modeled Hs (JONSWAP) against other local studies. Considering its relevance in design strategies for offshore structures, this research contributed to the understanding of the nonlinear effects of alpha and gamma parameters over the Hs and Tp during variations of water depth and wave states, easing the selection of the model coefficients.

The damage caused by tsunamis to coastal communities is often not only the result of the flowing water itself, but also of transported debris. Although there have been efforts to characterize forces from single-debris impacts, a more general scenario of multiple-debris impacts has not been studied experimentally. To address this need, experimental studies were performed, considering the effect of debris orientation and the number of debris field components on peak impact and damming forces on coastal structures. These forces are evaluated both qualitatively and quantitatively to provide insight into the nature of these impacts. For a few selected cases, a number of trials were conducted and an initial statistical study of the debris field collision phenomena performed. Observed forces and results are presented in terms of normalized quantities using analytical equations commonly used to calculate impact or drag forces. The lessons from this work provide an initial data set that can be used to guide further experimental and numerical studies on debris-laden tsunami flows.

The growing demand for maritime transport imposes several challenges to port authorities, including reducing port congestion, planning for expansion projects, and allocating budgets for such capital projects. To address these construction planning problems, there is a vital need to identify the factors that influence port congestion and understand their impact on port expansion and reconstruction planning. This study focuses on: (1) identifying the decision variables that influence port expansion and reconstruction decisions; (2) modeling the impacts of these variables on the decision to expand a port; and (3) developing an automated system to forecast port expansion needs. The automated system employs a mixed-integer nonlinear programming model that is designed to predict port performance, given a projected increase in cargo demand. The developed model is empirically validated using real data acquired from Shuwaikh Port. For the projected 1.8% increase in cargo demand, it was concluded that the port will need expansion in 8 years. The present study contributes to the core body of knowledge of port construction engineering and management by providing a novel model and a practical automated system for projecting port expansion needs using real-time port data. This should prove useful to port authorities and construction planners as it facilitates the advancement of port construction planning, enhances port operational safety, and provides the capacity to predict port expansion and modernization needs.

The soil around offshore foundations usually suffers from local scour, which is widely believed to undermine the bearing capacity and serviceability of the foundations. However, the extent to which this undermining effect could be less clear when considering the foundation is subjected to an earthquake. This paper presents a set of centrifuge modeling tests on single piles, with a prototype diameter (D) of 1.5 m and a first-order natural frequency highly comparable to that of a prototype wind turbine. Two model piles with the same dimension and stiffness, but installed with and without a scour hole (2D in depth), were used to investigate the local scour effect on the seismic response of the pile and the soil around through comparison. The seismic pile–soil interaction was interpreted in terms of dynamic p–y curves derived from the measured bending moment along the pile shaft and acceleration at different soil depths. It was found that the existence of the scour hole reduced the first-order natural frequency of the pile by 15%, increased the bending moment along the pile by up to 90%, and increased the lateral displacement amplitude of the pile head by 37%. The scoured pile had lower seismic stiffness than the benchmark pile during shaking, and the seismic stiffness of both piles finally decreased to only 20% of the static stiffness. These results highlight the necessity to treat the scour effect on both dynamic and static responses of pile foundations with great caution. Owing to the facts that the state of the soil around the scoured pile transitions from normal consolidation to overconsolidation and that the presence of soil above the scour base inhibited the accumulation of excess pore pressure, the current design principle that all soils above the scour base should not be accounted for is deemed overly conservative.

Water level oscillations induced by the ground motion of an earthquake have occasionally been observed in a closed or partially enclosed water system. The generated water disturbances can induce localized flooding, boat collisions, breakage/damage of moored cables due to water disturbances, or even the capsizing of vessels. In this study, the authors focused on cases of seismic water level oscillations in canals and attempted to investigate the potential hazards of and effective countermeasures against them through numerical simulations. The proposed numerical simulation model was first validated by reproducing the water level oscillation that was actually observed at a canal in Mexico City (Xochimilco Canal) during the 2017 Central Mexico Earthquake. The method was then applied to one of the canals in Tokyo (Keihin Canal) to clarify the potential water level fluctuations that can take place due to this phenomenon. The results indicate that while the risks of local inundation would be low, small boats, which can be found in many places in the canal, are at risk of capsizing. Finally, the use of wave-dissipating blocks was found to be an effective countermeasure to decrease the potential for a significant seismic water level oscillation to take place in this canal.

Model simulations using a depth-averaged ocean circulation model (ADCIRC) two-way coupled with a wave model (STWAVE) through the Coastal Storm Modeling System Coupling Framework (CSTORM-MS) are compared with observations made in the shallow, two-inlet tidal Katama Bay system on the Atlantic coast of Martha's Vineyard, Massachusetts, during Hurricane Irene. The CSTORM-MS framework integrates high-resolution bathymetric grids of this system with the North Atlantic Coast Comprehensive Study (NACCS) performed by the United States Army Corps of Engineers. The effects of bathymetric resolution and wave-flow coupling on the accuracy of modeled storm surge were investigated by comparing observations with the high bathymetric resolution, coupled model (CSTORM), a high-resolution uncoupled ADCIRC model, and a low bathymetric resolution, coupled model (NACCS). During the peak storm surge period, the coupled model using high-spatial resolution bathymetry reduced error in the study area by over 30% compared with the lower-resolution NACCS model, and by 16% compared with the high-resolution, uncoupled ADCIRC model. In addition, the high-resolution models indicate alongshore flows with magnitudes over 2.0 m/s along the southern coast of Martha's Vineyard, and a net northward circulation through Katama Bay and Edgartown Channel, which are not apparent in the lower-resolution simulations. Contrary to prior research suggesting small, if any setup in the Katama Bay system from wave forcing, in the extreme wave forcing event discussed here, the northward flux through Katama Inlet on the south side of the bay does not exit completely through Edgartown Channel on the north side of Katama Bay. Thus, the drainage path is not adequate to prevent increased water elevation in the bay, resulting in a setup within Katama Bay during the peak surge event, highlighting the need for adequate model resolution for local storm surge predictions.

To protect Ho Chi Minh City (HCMC) from submergence due to the ongoing rapid sea level rise (SLR), the Vietnamese government have proposed the construction of a sea dike in Can Gio Bay. Can Gio Bay will be closed to regulate the storage and to control water levels in the drainage and sewer systems of HCMC. This could significantly impact the salinity distribution in the Bay and affect its mangrove forest. In this study, a set of scenarios will be analyzed using two-dimensional hydrodynamic and convective-dispersive models to assess the effects of SLR and the construction of a sea dike on salinity distribution in the Bay. The results reveal that the salinity in most areas of the Bay tended to increase positively with the SLR. The sea dikes significantly reduced seawater intrusion into half of the upstream area of the Bay. Considering the influence of SLR and the construction of a sea dike, the sea dike could result in the reduction of salinity. Furthermore, if the sea dike was operated for a long time, half of the Bay area would become freshwater, which would lead to adverse effects on the mangrove forest.