A Study Of Complexity Of Erosional/accretionary Evolution In Large Estuary Based On GIS

The interaction of land and ocean is one of the important research under the program of IGBP; on the other hand, it is a central field having been financed by the oceanographical ministry of national physical science fund these years. The estuary is the typical region of land and ocean interaction. Due to the undisciplined exploitation during the last decades, the influx of water and bedload into sea has changed greatly; accordingly, the evolvement of landform near the estuary has been affected. The Yangtse River estuary takes on an important scientific value as a famous large estuary in the world. Based on the National '973' Project, National Physical Science Fund and, Science and Technology Project of Shanghai, this paper studies the complexity of erosional/accretionary evolution in the Yangtse Estuary. It is expected that the evolution of the Yangtse River estuary can be understood more profoundly and that this research can provide some help for the exploitation and protection of this area.The Yangtse estuary branches at Xuliujing (Grade Three branch) and the river infloods the sea through the four estuaries of Beizhi, Beigang, Beicao and Nancao. There exists a square-built river mouth bar system composed of tidal shoals alternating with channels in the gateway and a large delta under water outside the gateway reaching near to 123°E. The objects studied in this paper comprise these branch channels (not including Beizhi due to far limited topography data), the river mouth bar and delta. The complexity of erosional/accretionary evolution and other correlative problems in the last half century in the Yangtse River Estuary are mainly discussed on the basis of GIS technique, DEM technique, physiognomy, silt dynamics and statistics.