NUMERICAL STUDY ON THE DIFFERENCE OF GEOMORPHIC DYNAMICS BETWEEN THE CURRENT AND ABANDONED ESTUARY COASTS OF THE YELLOW RIVER

Waves are one of the important driving factors that shape the estuary and coastal landscape of the Yellow River Delta. Based on the Delft3D model coupled hydrodynamic and sediment transport module, this study aims to simulate the variation of surface suspended sediment concentration in the Yellow River under different seawater conditions. The current estuary and waste of the Qingshuigou channel of the Yellow River are quantitatively studied by the difference of suspended sediment concentration (Di value). The differences in ocean dynamics between the estuaries reveal the shaping of tidal currents and waves in the evolution of the Yellow River Delta in different periods. The results show that the suspended sediment concentration difference along the abandoned estuary and its nearshore area is generally high and positive under different sediment conditions in different periods. However, the Di value in the current estuary is generally negative. The abandoned estuary waves resuspend the deposited silt and clay, and move it off the coast by the tidal current, thus causing the coast to eclipse. However, due to the rapid input of a large number of Yellow River silt and clay, the current estuary cannot transport all of them out of the estuary in a short period of time, and thus the estuary and the coasts on both sides are deposited into the sea. In comparison, waves have a strong geomorphological effect on abandoned estuaries and coasts, and are relatively weak in the current estuary. These findings have important theoretical significance for understanding the evolution mechanism of dynamic geomorphology in the Yellow River Delta.