一种基于遥感数据快速提取水体信息的新方法

“数字流域”建设已成为水利现代化的重要组成部分。利用遥感技术进行水体信息提取可为构建数字流域提供重要的数据来源。在对Landsat ETM+影像上的水体及其背景地物进行光谱特征分析的基础上，发现水体在近红外和中红外波段（对应于Landsat数据的Band 4、Band 5和Band 7）同时具有强吸收这一典型特征，据此提出了一种新型的水体指数NWI（New Water Index）。其中，将Band 7用于水体指数模型的构建和水体信息的提取目前较少见于文献报道。以厦门岛为研究区，将该指数在经过大气校正的遥感影像上进行实验的结果表明：NWI可用于水体信息的快速有效提取，且具有较高的精度。

A New Method for Fast Information Extraction of Water Bodies Using Remotely Sensed Data

The construction of digital watershed plays an important role in the modernization process of water resources management and utilization in China.Using remote sensing technology to extract water information has become a significant way of providing data resources for digital watershed construction.In this paper,the unique characteristics of water bodies' simultaneous strong absorption at near and middle infrared bands (corresponding to the Band 4,Band 5 and Band 7 of Landsat TM/ETM+ imagery,respectively) has been revealed by a careful study of spectral features of water bodies with different surrounding land use/cover types,and based on that,a new water index (NWI) for water information extraction has been proposed.The new index distinguishes itself from other conventional water indexes by its usage of Band 7 of Landsat data which has rarely been reported in the literature.Using a ETM+ image acquired on March 4,2001 (path 119,row 43) and taking Xiamen Island as study area,the NWI,with atmospheric correction,has been tested in the reservoir,lake,sea and cage culture areas with various backgrounds.The overall accuracy of the water information extraction result reaches 90.4%.Therefore,it can be concluded that the NWI is effective in quickly and accurately extracting water information using remotely sensed data.