| Under the circumstance of global environment change and human activities becoming greater, the research of the shoals in estuaries, which lie in the interfaces between rivers and oceans is theoretically important. And the study of evolution of the shoals of the second and third generation alluvial islands, that is Changxing Island, Hengsha Island, Jiuduansha in the Changjiang Estuary for the past 150 years is practically important for understanding the evolution of the Changjiang Estuary, channel renovating, port planning and sustainable development of land resources. Supported by GIS, about 20 pieces of charts of the Changjiang Estuary are digitized and Digital elevation model (DEM) of the Changjiang Estuary in different periods is established with Kringing gridding method, based on which area, volume, the amount and thickness of erosion-accretion and bathymetric contour progradation rate are calculated.The results show that (1) the trend of the shoals from 1879 to 2000 is that deposition as a whole and progradation seaward along southeast with deposition rates faster than that of previous time, but deposition rates in different terms were different and erosion occurred in a few terms. About 1.948 billion t of sediment was deposited between 1879 and 2000, with average annual deposition rate of 16.1 million t, which amounts to 3.72% of sediment from the Changjiang River, and average annual thickness of 0.83cm, respectively. (2)The Hengshadongtan and Jiuduansha are the main positions of siltation, while the shoals of Changxing Island and Hengshaqiantan are the main positions of erosion. (3)GM (1,1) is established to study the evolution of the shoals in the future, and the results shows that the trend of the shoals in the future 25 to 50 years is deposition as a whole, but the velocity would decrease. (4)Though evolution of the shoals influenced by many factors, impacts of human activities on the shoals evolution is sharply increasing.
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