Abstract:

According to the data from 1958 to 2009,the relation between rate of erosion/deposition of the front sand islands and sediment elements of river basin was established in order to study the process and the trend of front sand islands evolution in Yangtze estuary.The results show that front delta above -5 m deposited from 1958 to 1989 and the rate slowed down from 1989 to 1997.From 1997 to 2000,the delta deposited because of the flood around the whole basin.But the delta kept on eroding from 2000 to 2009.The relation between rate of erosion/deposition and volume of water and sediment towards sea was also established.The critical volumes of water and sediment that keep balance of erosion and deposition were 283×108 tons per year and 0318 kg/m3 respectively.If the volume of sediment keeps the low degree after Three Gorges operation,the sand islands will erode to the degree of 1958,and the wetlands protection,natural resources and urban safety in Yangtze estuary will be seriously threatened.