长江口南槽最大浑浊带枯季大小潮悬沙峰特征及其动力机制

The maximum turbidity zone in the Changjiang (Yangtze) River estuarine is a key zone of land-ocean interaction. The river channels are throat of transportation between sea and river, and the evolution of the channels is closely hinged on the hydrodynamics of high-concentration suspended sediment. Based on in-situ measured data of flow velocity, salinity, and the size and concentration of suspended sediment at three stations in the South Passage in the estuary during the dry season, we analyzed the characteristics and hydrodynamics of SSC (suspended sediment concentration) peak in the maximum turbidity zone. The results indicate that the SSC increased 0.78-1.97 times from neap to spring due to the enhancement of flow velocity and sediments exchange between channel and shoal, and the fine sand flocculation increased the SSC peak during the slack tide, but the correlations of flow velocity and SSC, the particle size, and SSC all are nonlinear. In addition, the salinity gradient and SSC are correlated each other highly and linearly, demonstrating that an abrupt change of salinity gradient is the intrinsic and dynamic factor of sediment re-suspension and the formation of the SSC peak.