In order to study the re-suspension process and mechanism of sediment in estuary region under co-action of land-sea dynamics, based on the measurements of hydrology and sediment for 8 continuous days in the South Passage of the Yangtze River Estuary, the variation of tidal velocity, suspended sediment concentration ( SSC) , suspended sediment grain size with time and the re-suspension processes of bed sediment were studied. The results indicate that the flow dynamics and duration of flood tide and ebb tide have asymmetry features. From the neap tide to the spring tide, the SSC gradually increases, the suspended sediment is coarsening, the fine sand component increases slightly and its re-suspension is induced. The SSC reaches its peak three times during a tidal cycle. The variations of SSC and suspended sediment grain size are positively correlated with the tidal current velocity and bed shear stress.%为研究河口地区泥沙在陆海动力共同作用下的再悬浮过程和机制，基于长江口南槽河道连续8d的水文泥沙同步观测数据，对拦门沙河道潮流速、悬沙浓度、悬沙粒径随时间变化和河床沉积物再悬浮进行了分析研究。结果表明：涨、落潮的水动力和历时存在不对称性；水体悬沙浓度随小潮到大潮的变化而逐渐增加；水体悬沙粒径也随小潮至大潮的变化而不断粗化，但细砂含量略有增加，致使细砂类出现再悬浮现象；一个潮周期内，出现3次悬沙浓度峰值；水体悬沙浓度以及悬沙粒径的变化与流速及底床切应力都有着显著相关性。
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