 The Water Index, WI, is a technique used to identify and map water bodies in remote sensing imagery. It has been widely applied but suffers from several drawbacks such as difficulty identifying mixed water pixels, confusion of water bodies with background noise, and variations in threshold values due to location and time of image acquisition. To overcome these challenges, researchers have developed an automated method that combines the WI with digital image processing techniques. This method was tested using Landsat TM and ETM Plus images from three representative regions in China. The results showed that the new method outperforms existing thresholding methods, although the degree of improvement varies depending on the WI used. Additionally, the advantages and limitations of the proposed method are discussed. This article was authored by Hao Jian, Min Feng, Yu Chengzhu, and others.