Comparison of the Causes of Erosion–Deposition between Yellow River, Yangtze River, and Mekong River Subaqueous Delta l: Model Building

Abstract

An estuary delta is an area with active human economic activities and a fragile natural ecological environment. With the intensification of global changes and human activities, coastal and seabed erosion around the world is becoming more and more serious. This study compared the hydrodynamic effect and sediment diffusion path at the Yellow River subaqueous delta (river control type) and the Yangtze River subaqueous delta (tide-river type) in the East Asian monsoon area using a Delft 3D numerical simulation to analyse the causes of the distribution of accumulation and erosion landform in the different types of subaqueous deltas. This study found that the river deltas were dominated by the river when the accumulation landforms concentrated in the direction of the Coriolis forces, which was due to hydrodynamic erosion driven by wind, and the sediment diffusion range was mainly concentrated in shallow water areas (water depth < 6 m), resulting the Yellow River subaqueous delta presenting the pattern of “northern erosion and south accumulation”. The Yangtze River subaqueous delta was controlled by tidal effects, making the southern part of the estuary more susceptible to erosion. The research results can not only further deepen the understanding of the physical process and mechanism of erosion and deposition in the subaqueous delta but also provide stronger scientific support for the deltas’ ecological environment protection, geological environment safety, and disaster geology prevention.

Sediment Dynamics in Coastal and Marine Environments: Scientific Advances

“…The complexity of physical and chemical processes in estuaries is largely due to the size of the rivers, tidal action, mixing of salt and fresh water, flocculation and sedimentation of sediments, and frequent action of wind and waves. Li et al [8,9] used Delft 3D numerical simulation to compare the hydrodynamic effects and sediment dispersal paths in the Yellow River delta (river-controlled type) and Yangtze River delta (tidal type) of the East Asian monsoon region, as well as the Mekong River delta (tidal type). The findings of this study can be used to analyze river sediment distribution and to assess the impact of human activities on changes in river sediments and delta types.…”