Search Results (418)

Ensuring the long-term serviceability of nearshore breakwaters constructed on weak seabeds is important for sustainable port infrastructure. This study investigates the wave-induced dynamic response of a vibro-compaction sand-pile composite foundation used in the Jinpai Port breakwater project in Lingao, Hainan, China. A coupled wave–structure–seabed numerical model was established using FssiCAS. Four representative monitoring points were selected inside and outside the structural influence zone and at different burial depths. The displacement, effective stress, shear stress, and pore water pressure responses were analyzed by combining full-field contour distributions with local time-history results. The results show that the foundation response is strongly location-dependent. The maximum horizontal displacement follows the order D > C > A > B, with values of approximately 10.8, 7.6, 0.5, and 0.3 mm, respectively. The final settlement follows the order A > B > C > D, with values of approximately 84, 43, 31, and 19 mm, respectively. Residual pore pressure is more significant beneath the breakwater, especially at Point B. The breakwater toes, structural boundaries, shallow seabed, and improved–natural foundation transition zones are identified as stability-sensitive zones, providing guidance for targeted monitoring, local reinforcement, drainage improvement, and maintenance planning. Full article

Ultra-High-Frequency (UHF) or Ultra-High-Resolution (UHR) seismic data can image in detail several meters below the seafloor, especially in shallow waters, where the assessment of the subsurface is critical for future nearshore construction. The method can detect the subsurface structure in detail in UHF seismic records, which are characterized by a high amount of diffracted energy. With the aim of enhancing the lateral continuity and resolution for the reflectors, we applied a multipath summation approach for the first time at such high frequencies. We employed strategies for separating the diffractions from the total signal in order to clearly take advantage of their AI-located apices for further velocity analysis. The derived Root Mean Square (RMS) velocity models did not prove to be sufficient for direct migration, something that the multipath summation using 2D stacking weights sufficiently solved. We combined the focused-energy seismic sections with the derived interval-velocity models and took into consideration the available borehole data to interpret the subsurface structure. We observed a sufficient enhancement of the P-wave refraction velocity models commonly derived in such investigations. This enhancement involved not only the resolution but also the additional indications of velocity reversals, which can be a severe drawback for the stability of offshore infrastructure due to the possibility of their hazardous origin, such as fractures, unstable bedrock, or voids. Full article

Recent advances in satellite measurements make satellites suitable candidates for monitoring the ocean environment, especially in the case of offshore wave resources. In this context, the present work aims to evaluate the accuracy of the wave dataset provided by the European Space Agency’s Sea State Climate Change Initiative (or CCI-SS) project, in order to establish its viability to be used for renewable energy applications in general and those associated with some European locations in particular. Seventeen years of ERA5 data (2002–2018) are also considered for comparison with the satellite measurements. The first step is to derive the wave periods corresponding to the significant wave heights provided by the satellite from the ERA5 data by establishing a quadratic relationship between the significant wave height (Hs) and the wave period (Te). As a next step, the local wave conditions are expressed in terms of wave power distribution, also considering the performance of three wave energy generators with nominal power ranging from 250 to 3619 kW. By comparing with ERA5 data, it was observed that the CCI-SS dataset generally overestimates the wave energy for the sites located in the oceanic environment, also indicating much higher values for the converters with a rated power that does not exceed 1000 kW. Full article

In the context of global climate warming, sea surface temperature (SST) rise and sea level (SL) rise are projected to amplify typhoon-related marine dynamic disaster risks. These are idealized sensitivity experiments designed to isolate the individual effects of SST warming and SL rise, not full climate projections. This study investigates Super Typhoon Doksuri (2023) using the WRF-SWAN-ROMS coupled model, with sensitivity experiments designed for SST (+0.8 °C, +2.0 °C, +3.5 °C) and SL rise (+0.4 m, +0.6 m, +0.8 m) scenarios referenced to IPCC AR6 projections. Results indicate that SST rise enhances typhoon intensity by approximately 16% at +3.5 °C, elevates mean wave height by 25.0%, and increases extreme significant wave height by 24.0%, with the extreme wave height sensitivity approximately 2.75 times that of the mean. Storm surge exhibits a nonlinear response, with the extreme surge sensitivity approximately 13.2 times that of the mean. SL rise has relatively minor effects on open sea areas but affects coastal regions notably, expanding the inundation area by approximately 47% under the 0.8 m scenario. The Taiwan Strait channeling effect amplifies wave heights and surges on the right side of the track. Comparative analysis suggests that SST indirectly amplifies disasters by enhancing typhoon intensity, while SL rise directly constrains nearshore dynamics through static water level elevation. These findings offer process-based insights into the contrasting physical mechanisms through which SST rise and SL rise affect coastal hazards in semi-enclosed regions and may inform future ensemble-based climate impact assessments. Full article

Coastal Louisiana continues to experience rapid wetland loss, increasing the exposure of marsh-creation containment dikes to storm-driven waves, erosion, and sediment loss. This study evaluated offshore-to-nearshore wave transformation, erosion risk reduction, wave runup, and hydrodynamic loading at a representative marsh-creation site in Plaquemines Parish, Louisiana. A 25-year return-period offshore wave condition was derived from long-term Wave Information Study hindcast data and propagated using the SWAN spectral wave model. Two idealized foreshore conditions were examined: a bare-bed case and a marsh-roughened shallow water case represented through enhanced bottom friction. Web Soil Survey data were used to characterize the local soil context of the containment-dike zone. The results show strong wave attenuation across the inner shelf and marsh platform. Relative to the bare-bed case, marsh roughness reduced dike toe significant wave height by 16.1–27.4% and decreased the Hs²-based erosion exposure proxy by 29.6–47.4% across three still-water levels. These reductions produced 15.4–26.4% lower 2% exceedance runup and 28.5–45.8% lower quasi-hydrostatic loading on the containment dike. The results indicate that marsh-induced dissipation can help reduce erosion potential and support sustainable coastal restoration infrastructure management. Full article

Wave overtopping is one of the most complex coastal hazards to characterize in field conditions due to its high non-linearity and the interaction between unsteady hydrodynamics and wave–structure processes. To get insights into the underlying occurrence and persistence of overtopping, this study proposes an integration of numerical and data-driven models. Multi-month field observations made at a breakwater are used to investigate the hydro-meteorological parameters causing overtopping initiation and persistence. High-frequency video-derived overtopping detections are combined with coupled ADCIRC–UnSWAN (ADvanced CIRCulation–Unstructured Simulating WAves Nearshore) hindcasts to construct near-structure hydro-meteorological conditions. The results reveal a clear dynamical asymmetry showing that overtopping initiation corresponds to exceedance of crest elevation at individual wave-scale associated with elevated wave height, water level, wave steepness, and wind characteristics, whereas overtopping persistence depends on short-term temporal effects associated with wave energy, direction, and sustained water levels. Gradient-boosted decision trees, temporal convolutional networks, and Transformer models are employed, demonstrating that persistence cannot be inferred from instantaneous sea-states alone, indicating a separation of timescales between triggering and sustained overtopping dynamics. These findings provide field-scale evidence of distinct hydrodynamic regimes governing overtopping processes, highlighting the importance of temporal characteristics for understanding overtopping dynamics and developing predictive coastal hazard frameworks. Full article

Under climate change, the increasing typhoon intensity poses a severe threat to fishery harbor safety through storm surges and extreme waves. Traditional empirical management approaches fail to capture the complex wave-surge coupling inside harbors, leading to risk blind spots in berth allocation. This study enhances the fishery harbor disaster resilience by employing high-resolution coupled wave-storm surge modeling, taking Xinying Central Fishing Harbor (Hainan, China) during Super Typhoon Yagi (September 2024) as a case study. A Holland typhoon model integrated with ERA5 reanalysis data was used to reconstruct the wind field, which subsequently drove a one-way coupled MIKE 21 FM–SW model to simulate regional tides and deep-water waves. A Boussinesq wave model was then applied to resolve nearshore shallow-water wave transformations inside the harbor. Model validation showed strong agreement with observations: correlation coefficients of 0.97 for tides in Xinying station and 0.95, 0.97, 0.93 for significant wave heights in three buoys around Hainan island, with root-mean-square errors of 0.19 m and 0.67, 0.69, 0.31 m, respectively. The Boussinesq wave simulations revealed detailed spatial distributions of wave heights inside the harbor during the typhoon. Based on these simulations, a dynamic berth zoning strategy was developed, mapping safety zones for different vessel sizes according to wave-height tolerance (e.g., ≤0.6 m for medium-sized trawlers). This framework can provide potential support for decision-making regarding fishing vessel refuge during typhoons, maximizing safe capacity while minimizing capsizing risks. Overall, this study demonstrates a feasible pathway from advanced numerical modeling to practical engineering management, supporting a transition from experience-based to data- and model-driven disaster prevention for coastal fishery harbors. Full article

As they are home to numerous significant ecosystems, natural resources, and a growing population, coastal regions are among the most vital locations on Earth. This study, pertaining to the east coast of the UAE, integrates nine distinct characteristics to provide a thorough methodology for assessing integrated coastal vulnerability. Land use and land cover (LULC), nearshore bathymetry, coastal geomorphology, coastal slope, shoreline erosion and deposition, population density, wave and tide, and nearshore benthic features are important parameters that are examined. For the first time, coastal benthic features are included to assess coastal vulnerability in this region. By combining the variably weighted rank values of the nine variables, an Integrated Coastal Vulnerability Index was created, which divides the coastline into low-, moderate-, and high-risk categories. The methodology improves the precision of regional risk assessments by combining these factors with data from real-time coastal surveillance. Approximately 26.4% of the UAE’s 178 km east coast (or 47.1 km) is at high risk, followed by 17.3% (or 30.9 km) at moderate risk and 56.3% (or 100.2 km) at low risk. The offshore areas of the east coast of the UAE are prone to shoaling and tunneling effects from incoming high waves at certain areas due to the concave-shaped bathymetry and medium-range canyons present, which exacerbate storm surges or tsunamis due to the shoaling effect. For a 3 m rise in sea level, most significantly, 5.58 km² of plantation and 14.39 km² of residential areas will be damaged in the Kalba and Fujairah regions. Additional commercial spaces totaling 1.07 km² will also have an impact, adding to the existing 2.59 km² of oil bunkers in Fujairah. More than 40,000 people who live within 3.0 m of the UAE’s east coast in six separate districts—Kalba, Fujairah City, Mirbah and Qidfa, Khorfakkan, Dadna and Bidya, and Dibba—will be impacted if a tsunami wave or storm surge of three meters strikes the east coast. Our results are intended to assist government agencies, coastal planners, and policymakers in the Northeast Emirates (Fujairah and Sharjah) in creating sustainable and successful adaptation and mitigation plans for areas most vulnerable to coastal hazards. In addition to enhancing scientific knowledge of coastal vulnerabilities, this integrative method is a useful tool for making well-informed decisions in the face of shifting socio-economic and climatic situations. Full article

Offshore pipeline landfall sections in tropical coastal zones are often exposed to dynamic hydrodynamic forcing, which may induce seabed erosion and wave-driven liquefaction and thereby affect burial stability. This study presents an integrated assessment of seabed stability for an offshore gas pipeline along the Sarawak coast of the South China Sea, aiming to support burial-depth design in the nearshore surf zone. A multi-model framework was applied to simulate regional hydrodynamics, sediment transport, storm-induced seabed morphodynamics, and wave-induced liquefaction. Model performance was evaluated using field observations, bathymetric survey data, and laboratory experimental results. The results indicate that the seabed remains generally stable under normal environmental conditions, whereas extreme storm-wave forcing may induce localized surf-zone erosion and shallow seabed weakening. Under the 100-year storm-wave scenarios, the maximum simulated erosion depth reaches approximately 0.82 m, and the potential liquefaction response is mainly confined to the upper approximately 1.0 m of the seabed. These results suggest that storm-induced morphodynamic cover loss and wave-induced degradation of near-surface soil support should be evaluated jointly. Based on this integrated process envelope, a minimum burial depth of 2 m is recommended as a conservative engineering requirement for the examined landfall conditions. This process-integrated assessment workflow offers an applicable reference for the design and risk mitigation of analogous offshore pipeline projects in tropical coastal zones. Full article

A wave-resource characterization along the coast of Vietnam was performed based on the 12-year period from 2007 to 2018, using the structured-grid Simulating WAves Nearshore (SWAN) model with a ~2.3 km spatial resolution. Extensive model validations were performed using an observed nearshore dataset and ERA5 offshore datasets. The wave parameters, significant wave height, wave period, total wave energy and omnidirectional wave power varied both spatially and temporally, with a strong seasonal pattern influenced by the northeast and southwest monsoons, with the impact of the northeast monsoon being stronger. Wave energy resources were highest in winter and lowest in summer, making the southcentral coast of Vietnam a prime location for wave energy harvesting. However, further feasibility and design studies are needed before wave farms can be established. The Gulf of Tonkin and the Gulf of Thailand had lower wave energy due to wind distribution, shadowing effects and changes in water depth. This study also noted the impact of ENSO phases on wave conditions. Year-round, El Niño generally weakened winds, leading to smaller waves and reduced wave energy, while La Niña had the opposite effect. Additionally, tropical cyclones can further amplify significant wave height, especially during both ENSO phases in July, thereby increasing wave energy. Full article

Meeting the growing demand for renewable energy production requires tapping into a variety of natural resources. Wave energy, while abundant, remains a challenging and often non-economic field. To address this, the present paper proposes and examines an innovative concept for a wave energy converter (WEC). Alongside survivability capabilities, the novel device enables simultaneous extraction of wave energy in two degrees of freedom and, with additional tuning for a range of sea states, achieves higher efficiency compared to existing technologies. As it does not require a link to the seabed or a wharf for production, the concept is suitable for deep water, hence offering higher potential relative to nearshore WECs. In this study, we present the proposed concept and its engineering simplicity, together with mathematical analysis and preliminary results that evaluate the device’s performance under regular and irregular sea conditions. Full article

This study proposes an integrated framework combining aerial photography of unmanned aerial vehicle (UAV), AI-based waterline detection, and a rigorous quality control (QC) scheme for estimating wave periods in the swash zone. The proposed approach automatically extracts instantaneous waterlines from high-resolution UAV videos and converts them into wave series using timestack analysis. The DeepUNet model achieved a pixel-level recognition score of 75.0% for both F1-score and Dice, demonstrating reliable performance in detecting thin waterline features. The integration of spatial and temporal QC further improves the robustness of waterline tracking and reduces false detections. Wave periods derived from wave series across different cross-sections in the swash zone exhibit spatial consistent and qualitative consistency when contextually compared with offshore data buoy observations, while the quantitative differences reflect variation in nearshore wave dynamics. These results confirm the feasibility and effectiveness of the proposed framework for high-resolution nearshore wave monitoring. Full article

Ras El-Bar, a premier historic coastal resort on Egypt’s Nile Delta, has experienced a marked increase in drowning incidents in recent years, despite the presence of extensive coastal protection structures. While these measures, particularly detached breakwaters (DBWs), groins, and port jetties, were originally implemented to mitigate shoreline erosion, their influence on nearshore hydrodynamics and swimmer safety remains insufficiently understood. In this context, the present study integrates high-resolution bathymetric data, remote sensing observations, and coupled numerical modeling (CMS-Wave and CMS-Flow) to examine how these interventions have altered wave–current interactions. The results indicate that the modified coastal setting produces distinct flow regimes, ranging from weak offshore currents (<0.1 m/s) to moderate rip currents (≈0.25 m/s) within DBW shadow zones, and locally intensified flows exceeding 0.7 m/s in shallow nearshore areas. These conditions facilitate the development of vortices and persistent rip currents, particularly within inter-DBW embayments. A simulation-based swimming risk map was developed by integrating water depth and simulated current characteristics, classifying the coastline into safe, moderate-risk, and high-risk zones. High-risk zones, concentrated within inter-DBW embayments at depths exceeding 2 m, show broad spatial agreement with available drowning and rescue incident records, subject to the limitations of the informal dataset, while the shallow accretional shadow zones landward of the DBWs exhibit comparatively lower hydrodynamic energy and safer conditions. Overall, the study demonstrates that coastal protection structures, although effective in controlling erosion, may unintentionally increase human risk when safety considerations are not incorporated into their design and management. Accordingly, a set of integrated, sustainability-oriented measures is proposed, including enhanced real-time monitoring, regulated beach access, adaptive sand nourishment, and targeted public awareness, with the aim of achieving a more balanced and resilient approach to coastal zone management. Full article

Sandy shorelines respond to variability in boundary conditions over a wide range of time and spatial scales. While recent studies show that climate modes may affect shoreline evolution at interannual scales, such relationships remain unclear in the South Atlantic Ocean. Here, we investigate whether climate mode-driven variability in wave climate influences shoreline evolution using Ilha Comprida, a barrier island on the southeastern Brazilian coast, as a case study. Offshore wave conditions from the ERA5 reanalysis were analyzed over the last four decades and propagated to the nearshore using wave modeling. Shoreline change was quantified from satellite-derived shoreline positions, and relationships with interannual climate modes were evaluated using climate indices. Results show that the wave climate is bimodal and dominated by swell, with strong seasonality and no significant long-term trend in storminess. The El Niño–Southern Oscillation (ENSO) influences wave energy and extremes, with La Niña phases associated with higher wave power without a change in wave direction. No significant signal of the Southern Annular Mode (SAM) was found. At the coast, shoreline evolution is controlled by long-term sediment redistribution driven by alongshore transport gradients. ENSO-related shoreline signals are weak and spatially limited, occurring only in lower Empirical Orthogonal Function (EOF) modes of variability. These results suggest that, at Ilha Comprida, ENSO mainly modulates episodic wave-driven events rather than long-term shoreline patterns, emphasizing the need to distinguish between short-term energetic variability and longer-term morphodynamic response. This distinction is important for coastal management because even where climate modes do not produce persistent long-term shoreline trends due to site-specific aspects, they may still modulate event-scale risk, which can vary independently of the long-term average shoreline behavior. Full article

Photovoltaic systems deployed on large floating platforms in nearshore waters are strongly influenced by hydroelastic effects, nonlinear shallow-water waves, and variable bathymetry. This study develops a time-domain hydroelastic framework that couples the fully nonlinear non-hydrostatic wave model NHWAVE with a Rankine-source potential-flow solver and a discrete-module Cummins formulation. The wave model provides incident pressures and kinematics over uneven seabeds, while the potential-flow solver evaluates radiation and diffraction effects and transfers the resulting hydrodynamic coefficients into the time domain. Numerical simulations are carried out for a 600 m modular floating structure under regular waves over flat and sloped bathymetries with $tan\alpha =0.0133$, wave periods of 4–6 s, and wave heights of 0.3–1.0 m. The results show that bathymetric variation intensifies shoaling-induced excitation, modifies added-mass and damping distributions, increases the spatial non-uniformity of hydroelastic motions, and amplifies bending-moment RMS responses relative to the flat-bottom case. Additional comparisons between rigid-body and hydroelastic models show clear period-dependent redistribution of motions and bending demand. These results demonstrate that both local bathymetry and structural elasticity must be considered for the reliable analysis and design of nearshore floating photovoltaic systems and other large floating structures. Full article