Journal of Waterway, Port, Coastal, and Ocean Engineering

This paper presents a critical analysis of some selected codes and practical recommendations used as basic rules in the design procedures of modern marine fender systems. The first part of the discussion pertains to the existing equations used in calculating the eccentricity coefficient in the ship’s kinetic energy equation and the maximum allowable fender pitch (spacing) in a set of fenders installed along a quay wall. A new approach for the single-fender ship-to-fender contact mode during the side-berthing procedure is introduced, assuming three different special cases (i.e., the prequarter-point case, the quarter-point case, and the postquarter-point case) of the relative position of the ship’s hull with respect to the compressed fender unit. New equations are proposed for the maximum allowable fender pitch and the extreme berthing angles associated with the postquarter-point case of the single-fender and two-fender contact modes. Taking a ferry contact with an MV-type (or π-type) modular fender as an example, a detailed computational analysis has been performed, illustrating permissible geometrical ship-fender-quay configurations and their influence on the eccentricity coefficient, and, consequently, on the effective kinetic energy of a berthing ship.

The phase-averaged depth-integrated vegetal drag force (F_v) directly impacts the mean water level (MWL) change in vegetation. Evaluated from linear wave theory, F_v integrated along the submerged part of vegetation becomes zero due to the symmetric profile of horizontal velocity. In this study, a semianalytical model for estimating F_v on vegetation stems exposed to Stokes waves is developed based on Stokes second-order wave theory (STK). By assuming a narrow-banded wave spectral density and Rayleigh-distributed wave heights, the proposed model can be applied to random waves. STK-based formulas of the maximum depth-integrated vegetal drag force, bending moment, and bending stress are provided to assess the breakage of vegetation stems. Moreover, by taking the solutions from the stream function wave theory as references, the applicable ranges of the STK-based semianalytical model of F_v and drag-induced bending moment are determined.

Global ocean tide models have previously been reported to have substantial discrepancies in shallow coastal waters. Despite this, tidal forcing along the open boundaries of near-shore numerical hydrodynamic models is often driven by interpolating data of a global ocean tide model. This study compared tidal constants of two altimetry-constrained tide models [Ocean Topography Experiment (TOPEX)/POSEION Crossover Solution 8 (TPXO8) and Finite Element Solution 2014 (FES2014)] along the open boundary of a model in the Shinnecock Bay area of southern Long Island, New York, to investigate global ocean tide models’ discrepancies in this shallow-water location. The two tide models showed discrepancies of up to 1.18 cm in the predominant M₂ tidal constituent and up to 1.69 cm in the O₁ tidal constituent along the open boundary. To assess the impacts of the tide models’ discrepancies on tidal simulations, both tide models were used to force two different hydrodynamic models [Finite Volume Community Ocean Model (FVCOM) and Advanced Circulation Model (ADCIRC)]. On the basis of several performance measures, the authors conclude that tidal simulation results were affected more by the algorithm utilized rather than the choice of tide model, more so in the bay than in the open ocean.

Rising seas increase the exposure, vulnerability, and thus the risk associated with hurricane storm surge flooding across the coastal floodplain. A methodology is applied to down select a suite of synthetic storms from recent flood insurance studies. The purpose is to force wind-wave and hurricane storm surge models of the northern Gulf of Mexico (NGOM) coast (Mississippi, Alabama, and the Florida Panhandle) that represent the future landscape and derive the 1 and 0.2% annual chance floodplain for present-day and four sea-level-rise (SLR) scenarios. Vast new regions become part of the 100-year floodplain by the end of the century. In Mississippi, the present-day 500-year return period event is likely to be the 100-year event under an SLR of 1.2 m. Throughout most of Alabama and the Florida Panhandle, the present-day 500-year return period event becomes a 100-year event with just 0.5 m of SLR. Results indicate the need to apply a coastal dynamic modeling approach to plan and prepare for the effects of SLR across the NGOM and other low-gradient coastal landscapes.

An imaging-based method to estimate the nearshore bathymetry in the surf zone is described. The method uses imagery collected by an unmanned aircraft system (UAS), or a consumer drone. The UAS was flown over the area of interest to record video, and a particle image velocimetry (PIV) technique was then applied to analyze the image frames to retrieve the wave celerity. Using the shallow water approximation to the linear-wave dispersion relation, wave celerity from the imagery could be used to deduce the local water depth. After combining the water depth inversion at multiple points from within the area of interest, the bathymetry was constructed. To validate the method, water depths from 25 spatial points were surveyed with a total station during a trial in the nearshore surf zone at Freeport, Texas. The root-mean-square error (RMSE) was estimated as 0.132 m. By minimizing the RMSE, the correction factor that accounts for the wave nonlinearity in estimating wave celerity was estimated as 1.02. This new and simple approach provides simultaneous measurement of bathymetry and surface velocity field mainly in the surf zone, where breaking/broken waves and energetic sediment transport frequently dominate, and does not require a high-end UAS, resulting in greater flexibility in sampling across space and time.

This study aims to identify limitations during hydrodynamic forces estimation in offshore design standards, such as the RP 2A-WSD-2014, and presents an alternative method to estimate the hydrodynamics forces considering nonlinearities due to ocean–atmosphere interaction. La Guajira, Colombia, was the location as a study case for the proposed method. Simulating waves nearshore (SWAN) and Delft3D models were adapted for three scenarios of extreme waves. The calculation of hydrodynamic force profiles through the RP 2A-WSD-2014 method and the proposed method shows that the traditional method cannot reproduce current profiles associated to hydrodynamic nonlinear interactions. The analysis included sensitivity tests for the hydrodynamic model data; also, a structural numerical model using SAP2000 was built to assess the structural stability of a ductile monopile structure (stress and deformation analysis). The structural model intends to generate a contribution for predesign and reliability considerations. Finally, the method contributes to solve the data restrictions and guide to engineers to set objective security factors considering the theoretical profiles and numerical modeling.

A developed understanding of site-specific sediment transport processes is key for the assessment of coastal works, such as dredging and environmental management. This study investigates characteristics of the suspended sediment regime and sources of turbid water throughout a range of hydrodynamic conditions within a designated dredge placement area in Moreton Bay, Queensland, Australia. Field-monitoring campaigns were conducted prior, during, and post-dredge placements to evaluate the context of dredge material delivery with respect to natural suspended sediment drivers in proximity to the placement site. Elevated wind-wave events (wind velocity > 30 km h⁻¹) were strongly correlated with increased turbidity within shallow regions of the study area, classifying short-period waves as a significant source of background turbidity at the placement site. In situ suspended sediment concentration profiles post-dredging identified steep concentration gradients extending 1.5–3 m above the bed, whereby recently deposited unconsolidated sediment was entrained during the following flood-ebb tidal periods. The use of in situ particle-sizing techniques was instrumental in identifying large low-density flocculated material as the key transport form of fine cohesive fractions. The findings have implications for future dredge placement campaigns and will help to establish more robust assessment criteria for dredging operations. More generally, the observations contribute to understanding post-dredging water quality parameter ranges within dynamic coastal environments, such as Moreton Bay.