Effect of large-scale hydraulic projects on river regime evolution in north channel of Yangtze estuary

As a secondary inlet of the Yangtze estuary, the north channel experienced several large-scale hydraulic projects in recent decades,such as sand stabilization project in the separating pass of the south and north channels,Qingcaosha reservoir project and siltation promotion project in the Hengsha east shoal,etc.,which made the river regime more stable to some extent. Meanwhile,many new unexpected situations occurred following them,especially under the background of drastic decline in river sediment supply. The stability of sand bodies over the south side of Xingqiao channel was enhanced during the sand stabilization project in the separating pass of the south and north channels. However,the spilt ratio of the north channel decreased owing to the northward movement of the Biandansha shoal in this period. After the project of Qingcaosha reservoir,the upper part of the north channel kept scouring,with the development of Hengsha passage,the channel's curvature increased. Due to the siltation promotion project in the Hengsha east shoal as well as the natural deposition in the north channel mouth bar area,the northinlet of the north channel developed. However, the water-intaking program of avoiding saltwater and storing freshwater was seriously influenced by the strong flood current in this inlet.