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The geometry of the Long Island Sound (LIS) renders the wave field fetch-limited and leads to marked differences between western and eastern areas. The mechanisms that contribute to the formation and dissipation of waves in the LIS are not well understood. We evaluated the ability of the wave module of a wave-coupled hydrodynamic model to simulate different wind–wave scenarios. We were unable to capture wave statistics correctly using existing meteorological model results for wind forcing due to the low resolution of the models and their inability to resolve the LIS coastline sufficiently. To solve this problem, we modified the wind fields using in situ wind observations from buoys. We optimized both the Komen and Jansen parameterizations for the LIS to better present the peak winds during storms. Waves in the LIS develop more quickly than simple theory predicts due to quadruplet nonlinear wave–wave interaction effects. Removing quadruplet nonlinear wave–wave interaction increases the time to full saturation by 50%. The spatial distribution of wave energy density input reveals the complex interaction between wind and waves in the LIS, with the area of greatest exposure receiving higher wave energy density. The interaction of nonlinear wave–wave interaction and whitecapping dissipation defines the shape of the directional spectrum along the LIS. Dissipation due to whitecapping and shoaling are the main parameters modulating a fully developed wave field. [ABSTRACT FROM AUTHOR]

An accurate representation of physical and biological processes is crucial to resolve larval dispersal pathways and characterize connectivity of coral reef ecosystems. We investigate how hydrodynamic forcings drive larval retention rates during the bi‐annual mass coral spawning of the coral genus Acropora within a coral reef atoll (Mermaid Reef), located off northwestern Australia. By analyzing hydrodynamic conditions during 41 yr of historical spring and autumn coral spawning events, we identify typical and extreme hydrodynamic forcing conditions. Particle tracking using the output from a fine‐scale coupled wave‐flow hydrodynamic model forced with typical hydrodynamic conditions during coral spawning, revealed a mean transport of larvae eastward across the atoll. Transport was mainly driven by a combination of wave and tidal currents, where the residual tidal flow and unidirectional wave flow increased the net export of particles, and the oscillatory tidal (non‐residual) flow reduced the net export of particles from the reef. Importantly, however, numerical simulations forced with extreme hydrodynamic conditions generated by episodic tropical cyclones (11 out of 41 yr) showed large deviations from the typical eastward flow during autumn spawning, generating different connectivity pathways within the reef. Considering the substantial time larvae can be retained within reef systems, overlooking fine‐scale hydrodynamic processes may greatly overestimate larval transport distances between adjacent coral reef atolls. As a result, we emphasize the need to consider fine‐scale hydrodynamic processes within regional connectivity predictions, which is generally not considered yet critical to understand the capacity of reefs to recover following disturbances. [ABSTRACT FROM AUTHOR]

Abstract: Many low‐elevation, coral reef‐lined, tropical coasts are vulnerable to the effects of climate change, sea level rise, and wave‐induced flooding. The considerable morphological diversity of these coasts and the variability of the hydrodynamic forcing that they are exposed to make predicting wave‐induced flooding a challenge. A process‐based wave‐resolving hydrodynamic model (XBeach Non‐Hydrostatic, “XBNH”) was used to create a large synthetic database for use in a “Bayesian Estimator for Wave Attack in Reef Environments” (BEWARE), relating incident hydrodynamics and coral reef geomorphology to coastal flooding hazards on reef‐lined coasts. Building on previous work, BEWARE improves system understanding of reef hydrodynamics by examining the intrinsic reef and extrinsic forcing factors controlling runup and flooding on reef‐lined coasts. The Bayesian estimator has high predictive skill for the XBNH model outputs that are flooding indicators, and was validated for a number of available field cases. It was found that, in order to accurately predict flooding hazards, water depth over the reef flat, incident wave conditions, and reef flat width are the most essential factors, whereas other factors such as beach slope and bed friction due to the presence or absence of corals are less important. BEWARE is a potentially powerful tool for use in early warning systems or risk assessment studies, and can be used to make projections about how wave‐induced flooding on coral reef‐lined coasts may change due to climate change. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Physics is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Traveling Langmuir waves are numerically simulated in a warm plasma using a kinetic description of the process. Waves of this type can be excited by a powerful short laser pulse (the so-called wake wave). It is shown that the propagation velocities of perturbations at the moments of the distribution function of the second and third orders significantly exceed the propagation velocity of the charge density wave. The comparison of kinetic and hydrodynamic models on the example of the considered problem is the important aspect of this study. It is shown that the hydrodynamic model without taking into account the heat flux does not give a good approximation to the solution of the kinetic Vlasov equation. As a result, the closure problem for moment equations remains open. [ABSTRACT FROM AUTHOR]

The dissolved oxygen (DO) levels of coastal ocean waters have decreased over the last few decades in part because of the increase in surface and subsurface water temperature caused by climate change, the reduction in ocean ventilation, and the increase in stratification and eutrophication. In addition, biological and human activity in coastal zones, bays, and estuaries has contributed to the acceleration of current oxygen loss. The Patagonian fjord and channel system is one world region where low-DO water (LDOW, 30 %–60 % oxygen saturation) and hypoxia conditions (<30 % oxygen saturation, 2 mL L -1 or 89.2 µ mol L -1) are observed. An in situ dataset of hydrographic and biogeochemical variables (1507 stations), collected from sporadic oceanographic cruises between 1970 and 2021, was used to evaluate the mechanisms involved in the presence of LDOW and hypoxic conditions in northern Patagonian fjords. Results denoted areas with LDOW and hypoxia coinciding with the accumulation of inorganic nutrients and the presence of salty and oxygen-poor Equatorial Subsurface Water mass. The role of biological activity in oxygen reduction was evident in the dominance of community respiration over gross primary production. This study elucidates the physical and biogeochemical processes contributing to hypoxia and LDOW in the northern Patagonian fjords, highlighting the significance of performing multidisciplinary research and combining observational and modeling work. This approach underscores the importance of a holistic understanding of the subject, encompassing both real-world observations and insights provided by modeling techniques. [ABSTRACT FROM AUTHOR]

Nearshore hydrodynamics and sediment transport patterns induced by waves and tide adjacent to a structured tidal inlet with complex bathymetry are investigated to determine the potential causes of downdrift beach erosion. A coupled wave and hydrodynamic model is used to simulate the nearshore hydrodynamics and morphodynamics. Near the inlet, the tidal-induced pressure gradient dominates the wave radiation stress gradient only in the first half of the flood duration. The nearshore hydrodynamic pattern for the rest of the tidal cycle is driven mainly by the wave-driven pressure gradient. The wave-driven pressure gradient results from alongshore variation of water surface elevation induced by nearshore wave focal points caused by wave refraction over irregular bathymetry (with ebb tidal shoals and nonparallel shoreline depth contours). The resulting alongshore sediment transport patterns suggest that the direction of the time-averaged alongshore sediment transport rate near the inlet and at the downdrift beach is against that of the larger-scale net sediment transport along the coast. The inlet-adjacent time-averaged alongshore sediment transport rate increases for waves with larger wave height and an incident angle closer to shore normal in contrast to expectations under the assumption of straight and parallel depth contours. [ABSTRACT FROM AUTHOR]

Surface plasmons are collective excitations of electrons at the interface of a metal or plasma with a dielectric or vacuum. Due to their unique properties, this field has found numerous applications in nano-scale electronic devices, biomedical sensors, and electronic signal transmission. Thus, in this paper, we theoretically investigate the propagation of surface plasmon waves on the interface between a vacuum and a quantum plasma by deriving the dispersion relation using the quantum hydrodynamic model and applying boundary conditions. The main focus of the present study is to examine the effect of Fermi electron pressure, quantum Bohm potential, electron-exchange potential, and viscosity on the propagation and decay of surface plasmon waves in semi-bounded collisional quantum plasmas. In the electrostatic limit, the results show that the quantum effects, including Bohm potential and electron-exchange potential, facilitate the propagation of the surface plasmon waves. Also, the collision and viscosity effects have a significant role in the decay of these waves. [ABSTRACT FROM AUTHOR]

Hurricane Ike, which struck the United States in September 2008, was the ninth most expensive hurricane in terms of damages. It caused nearly USD 30 billion in damage after making landfall on the Bolivar Peninsula, Texas. We used the Delft3d-FM/SWAN hydrodynamic and spectral wave model to simulate the storm surge inundation around Galveston Bay during Hurricane Ike. Damage curves were established through the relationship between eight hydrodynamic parameters (water depth, flow velocity, unit discharge, flow momentum flux, significant wave height, wave energy flux, total water depth (flow depth plus wave height), and total (flow plus wave) force) simulated by the model and National Flood Insurance Program (NFIP) insurance damage data. The NFIP insurance database contains a large amount of building damage data, building stories, and elevation, as well as other information from the Ike event. We found that the damage curves are sensitive to the model grid resolution, building elevation, and the number of stories. We also found that the resulting damage functions are steeper than those developed for residential structures in many other locations. [ABSTRACT FROM AUTHOR]

The vulnerability to coastal disasters resulting from storm surges and wave overtopping (WOT) during typhoon intrusions is significantly escalating due to rising sea levels. In particular, coastal seawalls constructed along the coast through engineered assessments are experiencing an increase in the frequency of WOT and associated flooding in proportion to the reduction in freeboard due to rising sea levels. This study employed a unified modeling system that combines an empirical formula for estimating WOT volumes with a numerical model simulating tides, waves, and storm surges. The analysis was conducted across the Northwest Pacific (NWP) Ocean, encompassing coastal seawalls and terrestrial regions, using an integrated seamless grid system, which utilized ADCIRC + SWAN + EurOtop, for the present day, 2050, 2070, and 2100 to investigate how vulnerability to WOT changes with sea level rise. The maximum envelope of WOT inundation results for three historical and two 100-year return period synthetic typhoons confirms that vulnerability to WOT intensifies with rising sea levels. The single-process integrated model applied in this study can serve not only for long-term coastal seawall protection design but also for the short-term early warning system for storm surges and WOT, contributing to immediate preparedness efforts. [ABSTRACT FROM AUTHOR]

The ship-generated waves in restricted waterways can influence the behavior of sediment resuspension and bank erosion. This paper explores the case study considering the effect of ship-generated waves in restricted channels. A fully nonlinear Boussinesq model (FUNWAVE-TVD) is used to simulate the ship-generated waves. The sediment transport model adopted in FUNWAVE has been changed to incorporate the modified diffusion coefficients, deposition flux, and an explicit equation for settling velocity and critical shield parameter. The sediment transport model was validated against the experimental results of solitary waves in a wave tank, and model performance in shoreline geometry was reported. The implementation of the moving vessel in the numerical model and its impact on suspended sediment concentration were evaluated against the field measurements in the Falta stretch of the Hooghly river in Indian National Waterway 1. The error value in predicting the depth-averaged suspended sediment concentration by the FUNWAVE module was 97.6%, which has been significantly reduced to 16.3% based on the present modification. The parametric study of the ship waves in a typical restricted waterway of India revealed that the concentration of the sediments gradually decreases from the navigation channel to the river banks due to dissipation in the ship waves. The change in wave height and depth-averaged sediment concentration increases with the increasing depth Froude number. Finally, the impact on sediment transport due to different scenarios, such as the movement of two vessels in close proximity, the passage of vehicles coming from the opposite direction on the navigation channel, the influence of small draft vessels, and the bed morphology changes due to the multiple vessel movements are analyzed and reported. [ABSTRACT FROM AUTHOR]

An accurate prediction of near-shore sea-state is imperative during extreme events such as cyclones required in an operational centre. The mutual interaction between physical processes such as tides, waves and currents determine the physical environment for any coastal region, and hence the need of a parallelized coupled wave and hydrodynamic model. The present study is an application of various state-of-art models such as WRF, WAM, SWAN and ADCIRC used to couple and simulate a severe cyclonic storm Thane that developed in the Bay of Bengal during December 2011. The coupled model (ADCIRC–SWAN) was run in a parallel mode on a flexible unstructured mesh. Thane had its landfall on 30 December, 2011 between Cuddalore and Pondicherry where in-situ observations were available to validate model performance. Comprehensive experiment on the impact of meteorological forcing parameters with two forecasted tracks derived from WRF model, and JTWC best track on the overall performance of coupled model was assessed. Further an extensive validation experiment was performed for significant wave heights and surface currents during Thane event. The significant wave heights measured along satellite tracks by three satellites viz; ENVISAT, JASON-1 and JASON-2, as well in-situ near-shore buoy observation off Pondicherry was used for comparison with model results. In addition, qualitative validation was performed for model computed currents with HF Radar Observation off Cuddalore during Thane event. The importance of WRF atmospheric model during cyclones and its robustness in the coupled model performance is highlighted. This study signifies the importance of coupled parallel ADCIRC–SWAN model for operational needs during extreme events in the North Indian Ocean. [ABSTRACT FROM AUTHOR]

The paper investigates compound flooding from waves, sea surge and river flow in northern Jakarta, Indonesia, which is a global hotspot of flooding, by combining process-based coastal and river models. The coastal hydrodynamic modelling of Jakarta Bay in Indonesia shows that coastal storms can lead to a substantial increase in sea water level due to wind and wave setup in the nearshore areas, including Muara Angke river inlet. The compound flood hazard from a range of flood scenarios was simulated and analysed. The results reveal that low-lying areas around the river inlet are prone to flooding even during regular, low-intensity storm events, while rarer storms caused extensive floods. Floods were not caused by direct overwashing of sea defences but by overspill of the banks of the river inlet due to high sea water level caused by wind set up, wave setup, and sea surge obstructing the drainage of the river and elevating its water level during storms. We also found that the sea level rise combined with rapid land subsidence will inundate the existing coastal flood defences during storms in future. The majority of the city will be below mean sea level by 2100. The overflow of existing coastal defences will lead to extensive flooding in northern, western, and eastern Jakarta unless the defences are upgraded to keep up with future sea level rise. [ABSTRACT FROM AUTHOR]

The geomorphology of the Yangtze Estuary in the Changjiang River Delta in Eastern China has been the subject of extensive research. This study extends previous work to examine the influence of wind-waves on the mouth-bar, where about half of the river-borne material settles to the bed. The site is located just outside of Changjiang River mouth, which is meso-tidal and subject to seasonally varying river flows and wind-wave conditions. Modeling was performed with a coupled wave-current hydrodynamic model using TELEMAC and TOMAWAC and validated against observed data. Bottom Shear Stress (BSS) from river, tide and waves based on the numerical model output was used to infer the respective contribution to the evolution of the subaqueous delta. Our examination did not however extend to modeling the sediment transport or the morphological bed changes. The results suggest that (i) the dominance of river discharge is limited to an area inside the mouth, while outside, the mouth-bar is tide-wave dominant; (ii) considering just the tide, the currents on the shallow shoals are flood dominant and deep channels are ebb dominant, which induces continued accretion over the shallows and erodes the deeper parts of the mouth-bar until the tidal currents become too weak to transport sediment; (iii) whereas waves are very efficient at reshaping the shallow shoals, with the effect being subtly dependent on the depth distribution over the mouth-bar; (iv) the stability of shallow shoal morphology is highly dependent on the presence of seasonal wind-waves and characterized as “summer storing and winter erosion”, while deep channels perform like corridors of water and sediment, exporting sediment all year round. The nature of the mouth-bar response has important implications for coastal management, such as the ongoing deep water channel maintenance, reclamations and coastal defense measures. [ABSTRACT FROM AUTHOR]

Records of beach morphologic change and concurrent hydrodynamic forcing are needed to understand how coastlines in different environments change over time. This submission contains data for the period 2006 to 2021, for two contrasting macrotidal environments in southwest England: (i) cross-shore dominated, dissipative, sandy Perranporth Beach, Cornwall; and (ii) longshore-dominated, reflective gravel beaches within Start Bay, Devon. Data comprise monthly to annual beach profile surveys, annual merged topo-bathymetries, in addition to observed and numerically modelled wave and water levels. These data provide a valuable resource for modelling the behaviour of coastal types not covered by other currently available datasets. [ABSTRACT FROM AUTHOR]

A comprehensive review of state of the art numerical modeling in the field of sea bed morphology during cyclonic events is of vital importance. In this study a high impact and devastating cyclone, Vardah (2016) is considered to understand the hydrodynamic conditions, whereas, the recent cyclone, Nivar (2020) is considered for investigating the morphodynamic changes along the continental shelf region off the state of Tamilnadu, India. Three different models are coupled intrinsically to simulate hydrodynamics of tides and surges, waves and morphodynamic conditions. Initially, the hydrodynamic and wave models are established and validated with field measurements for an extreme event. Then, morphodynamic model is coupled with validated wave and tide model. Furthermore, the validation of bed evolution is performed for two cases viz., currents only and combination of waves and currents. The combined effect of tides, waves and surges improves the morphodynamic predictions. The present paper emphasizes the spatial and temporal morphological changes along the radius of cyclone pertaining to the shelf region. It is observed that the impact of cyclone on morphodynamics is predominant upto half the radius of the cyclone along the coast and upto 25 m contour from the coast across the shelf region. In this study, the bed evolution and its rate of change at various locations along the coast and across the shelf are extensively discussed. [ABSTRACT FROM AUTHOR]

To develop and utilize marine resources in the deep sea, the higher requirements for floating structures, which are operated in marine environment for a long term, have been put forward. Reasonable structure type and accurate force analysis are favorable guarantees to improve the survival performance and working performance of the floating structures. Floating spheres fastened by mooring cable were widely used in floating structures. In this paper, the wave forces of the floating sphere are efficiently and accurately calculated by solving the geometric relationship between the non-submerged floating sphere and wave surface. Combined with the hydrodynamic calculation of mooring cables based on the lumped mass method, the coupled motion model of multi-floating spheres fastened by multi-mooring cable was established under wave action. Furthermore, according to the floating structures fastened by mooring cable in the actual ocean engineering, the topological method of multi-mooring cables fastening the multifloating spheres was expounded from simple to complex. Finally, the modeling method and preliminarily hydrodynamic characteristics of the fastened floating structures, including the mooring system of renewable energy devices, ocean buoy, and coral nursery, were presented and analyzed in detail. The obtained results showed that the method for calculating the wave force on the floating sphere developed in this paper can accurately describe the motion process of the floating mooring sphere and the force on the mooring cable. Also, the topological method of multiple buoys and multiple mooring cables could efficiently establish various numerical hydrodynamic models of fastened buoys in ocean engineering. [ABSTRACT FROM AUTHOR]

Direct drive wave energy converters (DDWECs) have gradually become the mainstream of wave energy converters (WECs). In order to make better use of wave energy, energy storage devices and other renewable energy sources are often used to suppress power fluctuation in DDWECs. However, the addition of other energy sources will increase the complexity of the converter system and the number of power switches. Considering the flexibility of nine-switch converters (NSCs), this paper proposes a novel nine-switch grid-connected/off-grid multiport hybrid wave energy system (HWES). First, the system structure and modulation principle are described. Then, a model for a generator, a grid and energy storage are built, including a control strategy of each part. Finally, a simulation for the grid-connected/off-grid application and an experiment on the off-grid HWES are carried out. The results show that the multiport wave energy system can achieve the objective of stable and reliable power transmission by reducing power devices. [ABSTRACT FROM AUTHOR]

Process-based models have been employed extensively in the last decades for the prediction of coastal bed evolution in the medium term (1–5 years), under the combined action of waves and currents, due to their ability to resolve the dominant coastal processes. Despite their widespread application, they are associated with high demand for computational resources, rendering the annual prediction of the coastal bed evolution a tedious task. To combat this, wave input reduction methods are generally employed to reduce the sheer amount of sea-states to be simulated to assess the bed level changes. The purpose of this research is to further expand on the concept of input reduction methods by presenting a methodology combining numerical modelling and an Artificial Neural Network (ANN). The trained ANN is tasked with eliminating wave records unable to initiate sediment motion and hence further reduce the required computational times. The methodology was implemented in both an idealized and a real-field case study to examine the sensitivity, and produced very satisfactory predictions of the rates of bed level change, with respect to a benchmark simulation containing a very detailed wave climate. The obtained results have strong implications for further accelerating the demanding morphological simulations while enhancing the reliability and accuracy of model predictions. [ABSTRACT FROM AUTHOR]

The geometry of the Long Island Sound (LIS) renders the wave field fetch-limited and leads to marked differences between western and eastern areas. The mechanisms that contribute to the formation and dissipation of waves in the LIS are not well understood. We evaluated the ability of the wave module of a wave-coupled hydrodynamic model to simulate different wind–wave scenarios. We were unable to capture wave statistics correctly using existing meteorological model results for wind forcing due to the low resolution of the models and their inability to resolve the LIS coastline sufficiently. To solve this problem, we modified the wind fields using in situ wind observations from buoys. We optimized both the Komen and Jansen parameterizations for the LIS to better present the peak winds during storms. Waves in the LIS develop more quickly than simple theory predicts due to quadruplet nonlinear wave–wave interaction effects. Removing quadruplet nonlinear wave–wave interaction increases the time to full saturation by 50%. The spatial distribution of wave energy density input reveals the complex interaction between wind and waves in the LIS, with the area of greatest exposure receiving higher wave energy density. The interaction of nonlinear wave–wave interaction and whitecapping dissipation defines the shape of the directional spectrum along the LIS. Dissipation due to whitecapping and shoaling are the main parameters modulating a fully developed wave field.

Employing a long-wave mesoscopic hydrodynamic model for the film height evolution we study ensembles of pinned and sliding drops of a volatile liquid that continuously condense onto a chemically heterogeneous inclined substrate. Our analysis combines, on the one hand, path continuation techniques to determine bifurcation diagrams for the depinning of single drops of nonvolatile liquid on single hydrophilic spots on a partially wettable substrate and, on the other hand, time simulations of growth and depinning of individual condensing drops as well as of the long-time behaviour of large ensembles of such drops. Pinned drops grow on the hydrophilic spots, depin and slide along the substrate while merging with other pinned drops and smaller drops that slide more slowly, and possibly undergo a pearling instability. As a result, the collective behaviour converges to a stationary state where condensation and outflow balance. The main features of the emerging drop size distribution can then be related to single-drop bifurcation diagrams. [ABSTRACT FROM AUTHOR]

A coupled wave and hydrodynamic model was applied to the Kingston Basin of eastern Lake Ontario, a region with bathymetric variability due to channels and shoals, to assess the potential impacts on surface waves and wind-driven circulation of an offshore wind farm. The model was used to simulate a series of storm events with time-varying wind forcing and validated against wave, current and water level observations. The wind farm was simulated by adding semi-permeable structures in the surface wave model to represent the turbine monopiles, and by adding an energy loss term to the fluid momentum equations in the hydrodynamic model to represent the added drag of the monopiles on the flow. The results suggest that the wind farm would have a small influence on waves and circulation throughout the wind farm area, with spatial variability due to focussing of wave energy and re-direction of the flow. Overall, the results indicate that the wave height in coastal areas will be minimally affected with changes in significant wave height predicted to be < 3%. Larger changes to the strength of circulation occur inside the wind farm region with localized changes in current magnitude of up to 8 cm s − 1 . The results of this study may help to understand the impacts of future offshore wind farms and other offshore structures in the Great Lakes. [ABSTRACT FROM AUTHOR]

Storm-surge-induced coastal inundation constitutes a substantial threat to lives and properties along the vast coastline of the Bengal delta. Some of the deadliest cyclones in history made landfall in the Bengal delta region claiming more than half a million lives over the last five decades. Complex hydrodynamics and observational constraints have hindered the understanding of the risk of storm surge flooding of this low-lying (less than 5 m above mean sea level), densely populated (> 150 million) mega-delta. Here, we generated and analysed a storm surge database derived from a large ensemble of 3600 statistically and physically consistent synthetic storm events and a high-resolution storm surge modelling system. The storm surge modelling system is developed based on a custom high-accuracy regional bathymetry enabling us to estimate the surges with high confidence. From the storm surge dataset, we performed a robust probabilistic estimate of the storm surge extremes. Our ensemble estimate shows that there is a diverse range of water level extremes along the coast and the estuaries of the Bengal delta, with well-defined regional patterns. We confirm that the risk of inland storm surge flooding at a given return period is firmly controlled by the presence of coastal embankments and their height. We also conclude that about 10 % of the coastal population is living under the exposure of a 50-year return period inundation under current climate scenarios. In the face of ongoing climate change, which is likely to worsen the future storm surge hazard, we expect our flood maps to provide relevant information for coastal infrastructure engineering, risk zoning, resource allocation, and future research planning. [ABSTRACT FROM AUTHOR]

The Alburquerque Cay Islands belong to a group of western Caribbean atolls, with a barrier reef of coral that is more than 8 km in diameter. An understanding of the reef ocean dynamics and its direct relationship to the functioning of the ecosystem is important since the significant energies that are involved should play a fundamental role in the coral and fish distributions in the coral reef, which are fundamental for its sustainability. The microtidal regime and the predominance of the trade winds produces coastal circulation, which is induced by waves breaking against the barrier. The study of the water dynamics that are described in this paper was carried out by using a stationary model that is based on the shallow-water equations theory, with consideration to the radiation stress gradients in the waves, whose patterns were evaluated with the pseudo-data of a reanalysis of a virtual buoy in front of the atoll and were propagated in the domain of interest by using the simulating waves nearshore (SWAN) spectral model. The results demonstrate the bi-modal behavior of the currents of water jets, with the occurrence of extreme waves with velocities greater than 1 m/s along the barrier. For the mean wave regime, circulation occurred around the coral mounds. This circulation suggests that the reef, the orientation of which coincides with the direction of the predominant waves, was formed under these average conditions. The wave climate is primordial to the reef environment, and climate change may affect the coral health. [ABSTRACT FROM AUTHOR]

Microbial pollutants from coastal discharges can increase illness risks for swimmers and cause beach advisories. There is presently no predictive model for estimating the entrainment of pollution from coastal discharges into the surf zone. We present a novel, quantitative framework for estimating surf zone entrainment of pollution at a wave-dominant open beach. Using physical arguments, we identify a dimensionless parameter equal to the quotient of the surf zone width lsz and the cross-flow length scale of the discharge la = Mj 1/2/Usz, where Mj is the discharge's momentum flux and Usz is a representative alongshore velocity in the surf zone. We conducted numerical modeling of a nonbuoyant discharge at an alongshore uniform beach with constant slope using a wave-resolving hydrodynamic model. Using results from 144 numerical experiments we develop an empirical relationship between the surf zone entrainment rate α and lsz/la. The empirical relationship can reasonably explain seven measurements of surf zone entrainment at three diverse coastal discharges. This predictive relationship can be a useful tool in coastal water quality management and can be used to develop predictive beach water quality models. [ABSTRACT FROM AUTHOR]

As sea level rises and development of the coastal zone continues, coastal flooding poses an increasing risk to coastal communities. Wave runup can contribute many meters to the vertical reach of the sea, especially on steep gravel beaches, and wave overtopping is a key contributor to coastal flooding along coastlines exposed to energetic wave conditions. However, operational forecasting of wave overtopping has rarely been attempted due to the need for high-resolution inshore water levels and wave conditions, up-to-date coastal profile and sea defence information, and availability of models or formulae that can robustly predict overtopping for a range of coastal profile types. Here, we have developed and tested an efficient forecasting system for providing operational warnings up to three days in advance for the entire 1000 km coastline of southwest England, called SWEEP-OWWL, which is capable of predicting wave runup elevation and overtopping volumes along the energetic and macrotidal coastline, featuring embayed, sandy, gravel, and engineered regions. Existing flood warning systems have used the process-based hydrodynamic model XBeach, but due to the computational cost, have resorted to populating look-up tables using off-line simulations and only a single realisation of the coastal bathymetry. Instead, SWEEP-OWWL runs in 'real-time' using a computationally efficient suite of empirical shoaling, breaking, runup, and overtopping equations at 184 coastal profiles, forced with hydrodynamic information from a regional 1-km spectral wave and hydrodynamic model. Importantly, the forecast system can be updated with the latest coastal profile data with no extra computational cost, which is shown to improve the accuracy of predicted overtopping rate by an order of magnitude in some cases. Compared to visual observations of flooding events from live streaming webcams around the southwest, the system correctly predicted the presence or absence of wave overtopping with 97% accuracy and showed skill in differentiating between low and high hazard events. Reliable forecasts of wave overtopping could considerably enhance a coastal community's ability to prepare and mitigate against the risk to life, property, and infrastructure during coastal flooding events, and the developed system shows that this can be achieved using a single desktop PC for entire regions featuring both natural and man-made sea defences. • We develop and test an efficient forecast system for wave overtopping forewarning. • Predicts waves, water levels, and overtopping for 1000 km coastline on a desktop PC. • Correctly predicted the presence or absence of wave overtopping with 97% accuracy. • Can be updated with latest coastal profile data with no extra computational cost. • This is shown to improve the predicted overtopping rate by an order of magnitude. [ABSTRACT FROM AUTHOR]

The present work proposed a novel modular structural system with central tension-leg platforms and outermost wave energy converters (marked as MTLPW). The hydrodynamic interaction effect and the mechanical coupling effect between the WECs and the TLP have been taken into consideration, and the effects of key design parameters of the WEC on the hydrodynamic characteristics of the MTLPW system have been clarified. The results indicate that the outermost WEC can significantly reduce the surge response of the central TLP and produce considerable wave energy. In addition, the effects of different connection types, pretension levels and additional heave plates on the hydrodynamic performance of the MTLPW system have been further investigated, and the results indicate that both the outermost WEC module and the additional heave plate can be promising and available for improving the hydrodynamic performance of the initial MTLPW system. [ABSTRACT FROM AUTHOR]

A high-resolution Finite-Volume Coastal Ocean Model (FVCOM) inundation model has been developed for Dartmouth Town near Apponagansett Bay and Clarks Cove. Series of modeling experiments were conducted for the purpose of: (1) Assess the potential impacts of the climate-induced Sea Level Rise (SLR) on the storm-induced coastal inundation in Dartmouth Town; (2) Compare the current patterns, wave fields and surge distributions under different dynamic forces including winds in different directions and wave-current interaction; (3) Evaluate the impact of the bank on the flooding protection. Results show that under the hundred-year nor'easter storm condition, the climate-induced SLR could significantly enlarge possible flooding areas with the percent area enlargement of approximately 60% per foot of SLR. The directions of wind essentially determine the feature of the current patterns, wave and surge distributions. The northeasterly and easterly winds mainly threaten the western coast of the bay and the estuarine areas, and the southerly and southeasterly winds endanger the regions around the inner part of the bay. Wave-current interaction can change the current pattern nearshore, including formation of eddies and narrow alongshore currents, greatly enhancing the strength and complexity of the currents near the mouth of the bay. In addition, wave-induced surge tends to accumulate in the bay and near the estuary and coastal regions. The bank blocks a large amount of flooding current and waves into the bay and improves the local current and wave condition effectively near the mouth and in the bay. [ABSTRACT FROM AUTHOR]

Most wind turbine blades are assembled piece-by-piece onto the hub of a monopile-type offshore wind turbine using jack-up crane vessels. Despite the stable foundation of the lifting cranes, the mating process exhibits substantial relative responses amidst blade root and hub. These relative motions are combined effects of wave-induced monopile motions and wind-induced blade root motions, which can cause impact loads at the blade root's guide pin in the course of alignment procedure. Environmental parameters including the wind-wave misalignments play an important role for the safety of the installation tasks and govern the impact scenarios. The present study investigates the effects of wind-wave misalignments on the blade root mating process on a monopile-type offshore wind turbine. The dynamic responses including the impact velocities between root and hub in selected wind-wave misalignment conditions are investigated using multibody simulations. Furthermore, based on a finite element study, different impact-induced failure modes at the blade root for sideways and head-on impact scenarios, developed due to wind-wave misalignment conditions, are investigated. Finally, based on extreme value analyses of critical responses, safe domain for the mating task under different wind-wave misalignments is compared. The results show that although misaligned wind-wave conditions develop substantial relative motions between root and hub, aligned wind-wave conditions induce largest impact velocities and develop critical failure modes at a relatively low threshold velocity of impact. [ABSTRACT FROM AUTHOR]

Tropical cyclone-induced coastal inundation is a potential hazard for the east coast of India. In the present study, two case studies are presented to examine the significance and importance of wave radiation stress in storm surge modeling during two extreme weather events associated with the Phailin and Hudhud cyclones. Model computations were performed using the advanced circulation (ADCIRC) model and the coupled ADCIRC + SWAN (Simulating Waves Nearshore) model for these two events. Meteorological and astronomical forcing were used to simulate the hydrodynamic fields using the ADCIRC model run in a stand-alone mode, whereas the coupled ADCIRC + SWAN model also incorporated the wave radiation stress attributed from wave breaking effects. Cyclonic wind fields were generated using the revised Holland model. Results clearly indicate an increase in the peak surge of almost 20–30% by incorporating the wave radiation stress and resulting inundation scenario in the coupled model simulation. The validation exercise showed that the coupled ADCIRC + SWAN model performed better than the ADCIRC model in stand-alone mode. Key findings from the study indicate the importance of wave-induced setup due to radiation stress gradients and also the role of the coupled model in accurately simulating storm surge and associated coastal inundation, especially along flat-bottom topography. [ABSTRACT FROM AUTHOR]

Strauss, D.; Vieira da Silva, G.; da Silva, A.P.; Murray, T.; Faivre, G., and Wharton, C., 2020. Process-based modelling of a nearshore nourishment. In: Malvárez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 1297–1302. Coconut Creek (Florida), ISSN 0749-0208. Beach erosion and recovery morphodynamics are complex physical processes that are difficult to measure, particularly in the surf zone. Hence, with consideration of the respective advantages and limitations of the coastal morphological modelling approach to inform coastal management and climate adaptation strategies, the inclusion of these processes in predictive numerical models requires careful validation and interpretation. The timescale of their investigation dictates the optimal numerical modelling approach that should be applied to simulate and predict beach morphology changes. The level of detail and therefore, process understanding, obtained from numerical modeling ranges from 1D shoreline models to more sophisticated 3D physical process models. Here, we present the application and validation of a 3D process-based model (Delft3D) to simulate the dispersion of a nearshore beach nourishment in the outer surf zone at a highly variable (energy and direction) open coast beach on the east coast of Australia. [ABSTRACT FROM AUTHOR]

A plethora of physical parameters, such as hydro-, litho- and morpho-dynamic characteristics, are essential for understanding the response of coastal systems to intense sea states in terms of sediment transport and shoreline evolution. Nowadays, numerical models are extensively applied to meet the above needs and support coastal planning and management. In the present work, a 2DH dynamic modelling system is used for simulating the hydrodynamic and meteorological/oceanographic characteristics of the Saronic Gulf, in order to examine circulation patterns and predict sediment transport phenomena under high wave conditions at the coast of Varkiza, a sandy beach in the southern Attica, Greece. Time series of wind and wave data were used as input at the open boundaries of the model domain while the model was calibrated and validated through (linear and directional) statistical measures with respect to in situ wave measurements, since there was lack of hydrodynamic data at the site of interest. The simulation period of the model was between January 3 and February 19, 2013, with consecutive high waves in-between. The good agreement of the numerical results from the wave and hydrodynamic model with in situ measurements confirmed the suitability of the model for the support of sediment transport rates at Varkiza coastal segment. Model results reveal that there is a counter-clockwise water circulation during high waves that contribute to the erosion of the examined beach, which is also confirmed by independent field measurements.

The energetic, macrotidal shelf off South West England was used to investigate the influence of different tide and wave conditions and their interactions on regional sand transport patterns using a coupled hydrodynamic, wave, and sediment transport model. Residual currents and sediment transport patterns are important for the transport and distribution of littoral and shelf‐sea sediments, morphological evolution of the coastal and inner continental shelf zones, and coastal planning. Waves heavily influence sand transport across this macrotidal environment. Median (50% exceedance) waves enhance transport in the tidal direction. Extreme (1% exceedance) waves can reverse the dominant transport path, shift the dominant transport phase from flood to ebb, and activate sand transport below 120‐m depth. Wave‐tide interactions (encompassing radiation stresses, Stoke's drift, enhanced bottom‐friction and bed shear stress, refraction, current‐induced Doppler shift, and wave blocking) significantly and nonlinearly enhance sand transport, determined by differencing transport between coupled, wave‐only, and tide‐only simulations. A new continental shelf classification scheme is presented based on sand transport magnitude due to wave‐forcing, tide‐forcing, and nonlinear wave‐tide interactions. Classification changes between different wave/tide conditions have implications for sand transport direction and distribution across the shelf. Nonlinear interactions dominate sand transport during extreme waves at springs across most of this macrotidal shelf. At neaps, nonlinear interactions drive a significant proportion of sand transport under median and extreme waves despite negligible tide‐induced transport. This emphasizes the critical need to consider wave‐tide interactions when considering sand transport in energetic environments globally, where previously tides alone or uncoupled waves have been considered. Plain Language Summary: The South West UK has a large tidal range (macrotidal) and is exposed to high‐energy waves. We created a numerical model of this region, which calculates waves, tides, and sand transport over time. This was used to investigate the importance of waves, tides, and their interactions on the net movement of sand under different wave and tide states, which is important for evolution of the coastline and coastal planning. Sand transport is heavily influenced by waves. The interaction between waves and tides can contribute more to net sand transport than the summed contributions of waves and tides alone. Storm waves can cause sand movement at depths below 120 m and can reverse sand transport pathways. Key Points: Median waves enhance tidal sand transport vectors, whereas extreme waves can dominate sand transport and sometimes induce full reversalsA new continental shelf classification is presented based on wave‐, tide‐, and nonlinear wave‐tide interaction dominance of sand transportNonlinear wave‐tide interactions are a dominant or subdominant contributor to sand transport in extreme conditions and cannot be ignored [ABSTRACT FROM AUTHOR]