Recent river regime evolution of the North Branch of the Yangtze River estuary and development research of navigational channel resources

The North Branch of theYangtze River estuary was historically the main channel of the Yangtze River to the sea.The channel has been depositing and gradually turning into a tide channel under the impact of natural stream evolution at the estuary and man-made blocking dams since 1950's.Due to the sediment deposition in the mid of 1990's,the channel has not been navigable.Currently only experienced mariners lead native boats through the channel during tide flow.Based on the surveyed data,the paper presents the causes of variation of bank lines and the mainstream channel,and analyses the impacts of the beach reclamation on the River Regime at North Branch.It is summarized that under tide the navigation of 500-tonne vessels through the channel of North Branch is basically ensured,and the probability of navigation of 1000-tonne vessels reaches 90%.Given some remedial measures,such as locally dredging and regulating the shallow channel,it is feasible to resume the transportation of 1000-tonne vessels in the North Branch.