River Mouth Bar Formation and Evolution in Two Adjacent Estuaries Varying Waves and Estuarine Distance

Abstract

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.