Sediment transport in coastal areas under river influence: numerical simulation of erosion and deposition processes

This study investigates sediment transport in river-influenced coastal areas via numerical simulation, focusing on improving the critical shear stress method to accurately predict erosion-deposition patterns. A three-dimensional model integrating hydrodynamic, wave, and sediment transport modules was developed for a southeastern Chinese coastal region. Ten scenarios were simulated to compare traditional and improved critical shear stress methods under varying environmental conditions, validated using 2022-2023 field measurements. Results show the improved method reduces RMSE by 24% and increases correlation coefficients by 18% versus traditional approaches. Distinct transport patterns emerged under different hydrological conditions, with extreme events dominating sediment redistribution. River-wave interactions created complex transport dynamics, particularly when waves and currents aligned, enhancing bottom shear stress by 1.2-2.8 times. Integrating hydrodynamic processes, sediment properties, and morphological feedback improves representation of complex coastal dynamics. Climate change projections indicate sea-level rise may alter sediment transport non-linearly. This enhanced model offers practical tools for coastal management, navigation optimization, and infrastructure planning in river-dominated regions facing climate and anthropogenic pressures.