本文根据地物光谱特性和卫星的信号接收原理，提出了一种利用气象卫星识别水体的简单而有效的方法，使得薄云覆盖下的水体和云影中的水体得到较好的识别效果。在洪水监测中使用该方法，可以充分利用气象卫星数据获取丰富的洪水动态信息．并以１９９１年江淮洪涝灾害为背景，对试验结果进行了分析．

AVHRR data from Meteorological Satellites have potential in flood moni-toring due to the high time resolution and low cost.Unfortunately,AVHRR,whichis a kind of visible-infrared sensor,cannot detect land surface through cloud,andcloud- free image is quite rare during flood period due to the bad weather,so cloudcontamination is one of the main obstacles in flood monitoring using AVHRR data. Based on the spectral characteristics of groundcovers and the principle of satelliteobservation,this paper puts forward a simple but effective method for water iden-tification using AVHRR data, which is the ratio band of channel 2 by channel 1. By using this method,waterbody can be identified not only in cloud- free areas, butalso under semitransparent cloud and in cloud shadow.This method was used suc-cessfully in the 1 991 flood disaster in Huaihe river basin.