中文摘要：

北港是长江口的二级入海汊道。近年来,北港修建了诸多水利工程,如南北港分流口固沙工程、青草沙围水工程和横沙东滩促淤圈围工程等,它们对北港河势有一定的稳定作用,但在流域来沙锐减的背景下,也带来一些新的潜在问题。分流口固沙工程的建设一定程度上增强了新桥通道南侧沙体的稳定性,但与此同时,由于扁担沙尾部继续向新桥通道挤压推移,导致北港分流比减小。青草沙水库建设后,北港上段继续冲刷,由于横沙通道的不断发展,致使北港主槽曲率进一步增大。北港拦门沙河段的淤积和横沙东滩的促淤圈围工程促使了北港北汊的发展,但该汊道中增强的涨潮流对青草沙水库“蓄淡避咸”产生了一定的影响。

英文摘要：

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 north- inlet 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.