基于GIS和RS的长江口北槽冲淤可视化分析

Visualization Analysis of Erosion and Deposition in the North Channel of the Changjiang Estuary Based on GIS and RS

利用Landsat-5 TM遥感影像和实测水深值之间的相关性,建立遥感反演水深模型,用反演的1995年北槽水下地形和1992年实测资料进行冲淤分析。结果表明:1)运用该模型可以很好地反演出研究区水下地形,其平均相对误差为14.36%;2)1992-1995年北槽河段总体表现为冲刷,冲刷量为0.5873×108 m3;3)1992年北槽上段河型为南岸低北岸高,中下段河型为U型;1995年上段河型不变,中段变为倾斜线型,下段为缩窄U型。研究结果可为今后长江口北槽冲淤演变研究提供借鉴。

A mathematic model was constructed to retrieve the water depth information by using the relationship between reflectance derived from Landsat-5 TM satellite data and surveyed water depth. Erosion and deposition analysis was carried out based on the data concerning underwater topography of the north channel of Changjiang Estuary in 1995 retrieved from remote sensing image and water depth surveyed in 1992. The results indicate that, firstly, by this model, the underwater topographical data of the researched area can be retrieved accurately, with an average relative error of 14.36%; secondly, the north channel is generally characterized by erosion from 1992 to 1995, and the total erosion volume is 0.5873×10^8m^3; thirdly, the pattern of the upper reach of the north channel in 1992 appeared as lower south bank area and higher north bank area, and U-shape in the middle ＆ lower reach; in 1995, the pattern of the upper reach didn＇t vary, while that of the middle ＆ lower reach turned to gradient line type, and the lower part narrowed U-shape. The research results may serve as a reference for future research on the evolution of erosion and deposition in the north channel of the Changjiang Estuary.