Sources for saltwater intrusion at the water intake of Qingcaosha Reservoir in the Changjiang Estuary

Based on temporal variation of the simulated salinity and current direction,change of the isohaline and freshwater zone at flood slack and ebb slack,this study used the modified numerical 3-D model ECOM-si to analyze sources of saltwater intrusion at the water intake of Qingcaosha Reservoir under normal dynamic condition. The modeled results showed that saltwater-spill-over from the North Branch into the South Branch(SSO) accounts for 69.5%,89.3%,98.5% and 99.5% of the surface saltwater intrusion at the water intake of the Qingcaosha Reservoir during moderate tide following neap tide,spring tide,moderate tide following spring tide and neap tide,respectively,and 34.9%,88.9%,98.5%,99.5% of the bottom saltwater intrusion at the water intake of the reservoir during the same four-type tides mentioned above. Except for the bottom saltwater intrusion mainly from downstream open sea (accounts for 65.1%) during moderate tide following neap tide,the source of the saltwater intrusion at surface and bottom layer at the water intake of the reservoir is mainly from the SSO,especially during moderate tide following spring and neap tide.