River-bed evolution in the braided reach of the south and north passage after implementing Yangtze estuary deepwater navigational improvements

By using bathymetric chart and discharged flow data,the relation between the rive-bed evolution and change of discharged flow in the braided reach of the south and north passage is studied in this paper.After implementing Yangtze Estuary Deepwater Navigational Improvements,there are an decreasing trend and an increasing trend in the ratio of ebb flow diversion through the north passage and the south passage,respectively.The length of sediment deposited on the entrance region in the north passage is about 12 km long,and that of the eroded on the upper region in the south passage about 18 km.But the total cross-section area of the entrance reach in the north passage and south passage decreased from 1998 to 2006.There are good correlations between the total channe storage and the yearly averaged ebb flow ratio in the north passage,and the cross-section averaged depth of the entrance reach in the north passage and south passage and their yearly averaged ebb flow ratio,respectively.According to the relationship formula,the change of the ebb flow ratio and the cross-section averaged depth of the entrance reach in the north passage and south passage are evaluated.