Luming Shi

The estuary, located at the interface of land and sea, experiences variable dynamic conditions, resulting in complex sedimentary processes. This study uses Delft3D with coupled FLOW and WAVE modules to examine how waves and the distance between adjacent estuary mouths influence jet spreading and river mouth bar development. Results show that wave forcing enhances the lateral spreading of the jet, suppresses its longitudinal velocity, and increases bed shear stress. The spreading width is positively correlated with wave‐current energy ratio and normalized shear stress. A smaller promotes transverse jet merging, suppressing wave‐enhancement longitudinal jet spreading. Analysis of the geomorphic results reveals that the wave forcing speeds up the formation of the river mouth bar. Sediment deposition is primarily linked to the velocity gradient, whereas shear stress primarily influences sediment resuspension. When waves are weak, smaller inhibits the formation of the bar. Based on the shape of the bars, four mouth‐bar patterns are identified: circular bar, elongated bar, deflected bar, and absent bar. It is observed that both smaller and larger relative wave strength are not conducive to the formation of the bar.

High-resolution coastal wave reconstruction from atmospheric forcing is complicated by seasonally varying wind–wave responses. To account for this heterogeneity, we develop a Mixture-of-Experts U-Net that combines four season-oriented decoder experts with a feature-dependent gating network to reconstruct high-resolution fields of significant wave height, mean wave period, and mean wave direction directly from 10-m winds over the Yellow and Bohai Seas. The framework captures the major spatiotemporal variability of all three variables, although reconstruction skill differs because of distinct physical controls. Expert diagnostics reveal distinct seasonal and spatial skill among the experts, with the gating network assigning the largest weight to the season-matched expert while retaining non-zero contributions from remaining experts through soft routing. Adaptive fusion therefore effectively exploits the differentiated expert strengths and outperforms fixed single-expert reconstructions. Compared to conventional U-Net, the framework reduces the RMSE during high-energy events by 4.8-8.3% for significant wave height and 6.1-8.4% for mean wave period and reduces the cMAE of mean wave direction by 2.3-4.6%. Monte Carlo perturbation experiments further show reduced sensitivity to prescribed input uncertainty without sacrificing deterministic accuracy. These results demonstrate that adaptive fusion of season-oriented experts provides a robust framework for high-resolution coastal wave reconstruction under seasonally varying forcing.

The global transition to a diversified renewable energy portfolio requires reliable assessment of predictable marine energy resources. This study develops a high-resolution, three-dimensional Regional Ocean Modeling System (ROMS) to quantitatively evaluate theoretical tidal current energy resources in the Bohai and Yellow Seas. The model, configured with fine-scale bathymetry and forced by harmonic tidal constituents, is validated against tide gauge and Acoustic Doppler Current Profiler (ADCP) observations. Multi-year simulations reveal pronounced spatial heterogeneity in tidal current energy distribution. Rather than treating resource assessment as a single power density mapping exercise, this study combines annual mean theoretical power density, peak theoretical power density, threshold-dependent effective flow duration, effective water depth, current directionality, and vertical velocity structure to characterize resource intensity, temporal persistence, and vertical deployability. The results identify distinct hydrodynamic resource regimes. High theoretical resource intensity is concentrated west of Laotieshan Cape and east of Chengshantou, where cumulative annual effective flow duration exceeds 5000 h and short-term instantaneous theoretical power density can reach approximately 10 kW/m² and 8 kW/m², respectively. These peak values indicate strong local tidal acceleration but should be interpreted together with annual mean power density and effective flow duration. In contrast, the northern Jiangsu coastal area exhibits lower peak intensity but relatively persistent moderate flow conditions. The results provide a hydrodynamic resource basis for preliminary site screening and for guiding subsequent turbine-performance, wake/array, environmental, grid accessibility, and techno-economic assessments.

Long-period waves induce large orbital particle excursions and significantly compromise harbor operational safety. Conventional perforated breakwaters often exhibit limited attenuation under such conditions. To address this limitation, this study investigates long-period wave attenuation in a wave screen composite perforated breakwater through a combined program of laboratory experiments and numerical simulations. The structure integrates an asymmetric double-layer louver screen, a multilayer flat-plate array, and an ecological porous wall. Laboratory experiments were conducted on 16 combinations of louver arrangements, resistance serration layouts, and two ecological infill materials (coconut fiber and oyster shells). In parallel, a numerical model was established and compared with the experimental results to further analyze the internal flow behavior and attenuation characteristics of the proposed structure. Results show that the proposed structure maintains low transmission under medium and long wave conditions, with transmission coefficients below 0.37 for all configurations. The numerical results reproduce the main experimental trends reasonably well and further illustrate the internal flow-field features associated with wave attenuation. The attenuation sequential wave–structure interaction process is observed: flow separation, particle-motion redirection, and vortex generation around the seaward louver screens are followed by turbulence development and energy dissipation within the multilayer plates and porous core. Coconut fiber provides lower transmission and higher dissipation than oyster shells, likely due to its more complex porous morphology. Under long-period wave conditions, simply increasing resistance serrations does not necessarily reduce transmission, and the shape also affects the resulting transmission performance. These results provide new insight into long-period wave attenuation in permeable coastal structures.

Parametric tropical cyclone models are widely used to generate large wind field ensembles for assessing extreme storm tides and wave heights. The radius of maximum wind (RMW) is a key model parameter and is commonly estimated using empirical formulas. This study shows that uncertainty introduced by the choice of RMW formulas has been largely overlooked in tropical cyclone risk assessments. Using the Pearl River Estuary as a case study, historical wind fields (1981–2024) were generated with a parametric tropical cyclone model combined with eight empirical RMW formulas. Storm tides and wave heights during tropical cyclone events were simulated using a coupled wave–current model (ROMS–SWAN) and analyzed with extreme value theory. The results indicate that, for estuarine nearshore zones, the 100-year return period of water level and significant wave height vary by up to 1.26 m and 1.54 m, respectively, across all the selected RMW formulas. Joint probability analysis further shows that RMW uncertainty can shift the joint return period of the same compound storm tide and wave event from 100 years to 10 years. For an individual extreme event, differences in the RMW formula alone can produce deviations up to 2.11 m in peak storm tide levels and 3.8 m in significant wave heights. Such differences can also change the duration of extreme sea states by 13 h. These results highlight that RMW formula selection is a critical uncertainty factor, and related uncertainty should be considered in large-sample tropical cyclone hazard assessment and engineering design.