南汇──奉贤杭州湾北岸岸滩水下岸坡三维EOF分析

A Study on Nearshore Profiles from Nanhui to Fengxian Along the Northe Bank of Hangzhou Bay with 3D-EOF

本文根据南汇一奉贤杭州湾岸段1983～1990年1：2.5万水下地形图，在建立地形场数据库基础上，应用三维经验特征函数（EOF）方法，对该岸段的水下岸坡进行整体研究。第一特征函数的时空结构反映了80年代以来该岸段的冲淤基本格局，贡献率达67.90％;第二特征函数则反映了长江分水分沙对杭州湾北岸岸滩影响，贡献率为11.17％。研究结果表明南汇─奉贤岸滩在纵向和横向上的冲淤特点：纵向上以半渡港为界，以东呈淤积状态，以西整体呈冲刷趋势;横向上，8米等深线为─振动"节点"，冲淤呈反向变化。研究结果对这一地区的海岸带开发具有重要意义。

Based on the data base of digitized maps of nearshore from Nanhui to Fengxian long the north bank of Hangzhou Bay with a scale of 1: 25000 since 1983 to 1990, 3D emiprical orthogonal function (EOF) was first used to study the structure of temporal and spatial variation of the coastal evolution. The basic character of the near shore profiles evolution was expressed by the first emiprical orthogonal function, whose contribution rate was up to 67.90%. The second emiprical orthogonal function, whose contribution rate was 11. 17%, was used to explain the effect of the changes of the Changjiang Estuary on the near shore profiles evolution. It was proved that 3D-EOF was a very useful method to coastal research and the results of the present paper was of important significance to the coatal development and managent of the north bank of Hangzhou Bay.