Numerical Analysis on Impacts of the Project of North Branch Narrowing on Sediment Distribution at the North Branch in the Changjiang River Estuary

To analyze the effect of the project of North Branch Narrowing at Changjiang River on hydrodynamic and sediment transport, a 3D numerical model for Changjiang Estuary was established. The verification of the models shows that they are effectively for simulating tidal current and suspended sediment distribution. The model were then used to simulate the hydrodynamic and distribution of sediment after the north branch narrowing. The results show that, after the narrowing-project, the new shoreline direction conforms with the main current direction of tide, the characteristics of flooding and ebbing tide basically remains unchanged; the project narrows the estuary width of north branch. 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 concentrations of suspended sediment in the north branch would be reduced along with the reduce of tide level and current speed. The concentrations of suspended sediment reduce 0 to −14.9% after the project construction. It has little impact on the tidal level, current speed and suspended sediment concentration in the south branch in the Changjiang River.