Sediment exchange between southern yellow sea and Yangtze river Estuary in response to storm events

The pattern of sediment exchange between the Yangtze River Estuary and the southern Yellow Sea constitutes a crucial yet contentious line of scientific inquiry. This conundrum hampers our comprehensive understanding to predict the future morphological evolution of the radial sand ridges and Jiangsu tidal flats. This study investigates various processes, including tides, wind and waves, to identify the dominant factor controlling sediment exchange between the southern Yellow Sea and the Yangtze River Estuary under storm conditions, using a validated numerical model. Our results show that tide is the dominant force controlling hydrodynamics and sediment transport between the two systems. Tidally induced residual currents and sediment fluxes exhibit a consistent northwesterly trajectory, from the Yangtze River Estuary to the southern Yellow Sea. Conversely, the contributions of wind and wave-induced currents under normal wind conditions (Beaufort Scale 3, 3.4 m s⁻¹) adjust net sediment flux by less than 10 and 46–68%, respectively. In particular, the influence of wind and waves on sediment transport varies significantly with wind direction. While southerly or southeasterly winds amplify the tide-induced northwestward sediment transport, northerly or northeasterly winds curtail it. Under strong winter storm conditions, however, the perturbation caused by northerly winds and waves supersedes the influence of tides in controlling sediment transport, leading to a net residual current and sediment flux oriented southeastwards.