近半个世纪长江口九段沙湿地的冲淤演变

Evolution of Jiuduansha Wetland in the Changjiang River Estuary During the Last 50 Years

根据1958—2004年的系列地形图，在地理信息系统软件ArcGis8．2的支持下，探讨近半个世纪九段沙湿地演变过程。研究表明：九段沙在长期的自然淤积过程中既具有趋势性的渐变，又存在非趋势性的突变，北槽深水航道工程改变了九段沙的自然冲淤模式，使九段沙顶端至江亚南沙大片区域显著淤积，工程后期，淤积速率回落，九段沙形态稳定。

Based on the topographic maps dated from 1958 to 2004, supported by the GIS software ArcGis8.2, the paper mainly deals with the evolution of the Jiuduansha tidal island. The result shows that there have been tow basic types of change during the long course of natural siltation and erosion ： continuous change and periodic change. The former includes broadness of the island area, down stream migration of the head of tidal island and continuous siltation of the tail of tidal island. The latter includes the tidal island swaying south. On the other hand, the deep-water channel project at north passage of the Changjiang River changed the natural sultation pattern of Jiuduansha tidal island. A very large area from the head of Jiuduansha to Jiangyanan tidal island was silted greatly. The speed of accumulation declined and the shape of Jiuduansha tidal island leveled off after the project.