中文摘要：

基于ECOMSED模型建立了长江口地区潮流和泥沙输运数值模型。模型验证情况良好,能很好地模拟长江口地区水动力环境和泥沙浓度分布。利用所建模型,对长江口北支中束窄工程实施前后,长江口地区的水动力和泥沙浓度分布进行了模拟。研究结果表明：长江口北支中束窄工程实施之后,北支河道有较大程度的缩窄,北支径口也有较大程度的缩小,导致外海潮流对北支河道的侵入动力减弱,造成潮位降低,河道缩窄也使水流流速有所增加;北支河道内的泥沙浓度也随潮水侵入动力的减弱和潮位的降低而有所降低;北支中束窄工程仅对北支影响较大,南支及口门区域的潮位、流速、泥沙浓度基本不受影响。

英文摘要：

The numerical models of tidal current and suspended sediment concentration of the Yangtze River estuary were established based on ECOMSED model. The verification of the models shows that they are effectively for simulating tidal current and suspended sediment distribution in the Yangtze River estuary. The models were then used to simulate the hydrodynamic and distributionsof sediment before and after the north branch narrowing in the north branch of Yangtze River estuary. The numerical result shows that,after the north branch narrowing,the channel and the mouth of the north branch would be narrowed significantly,and tide would be weakened and water level would also be reduced,and tide current would be increased due to the narrowing of channel in the north branch. The numerical results also show that the concentrations of suspended sediment in the north branch would be reduced along with the reduce of tide. The north branch narrowing in the Yangtze River estuary would influence the tide current and suspended sediment concentration in the north branch,and it has little impact on the water level and tide current,and suspended sediment concentration in the south branch and the estuary area.