Numerical Study to Choose the Optimum Narrowing Schemes for Protecting Water Source in the South Branch of the Changjiang Estuary

A depth-averaged 2D numerical model is set up to simulate the hydrodynamics and salinity of the Changjiang Estuary with Delft3D-FLOW, which has been well calibrated and validated with the observed data of the tidal level, velocity and salinity of the Changjiang Estuary. The changes of the salinity under the different narrowing schemes in the North Branch of the Changjiang Estuary during a spring tide in the dry season when the discharge is 9,070m3/s at Datong gauging station are calculated. And the comparison shows that the middle narrowing scheme without plugging the right branch of Xinlongsha is the optimum one for reducing the saline water spilling from the North Branch to the South Branch and protecting water source in the South Branch of the Changjiang Estuary.