Satellite images and the Digital Elevation Model (DEM) can extract three major factors, such as topographic data, geologic patterns, and the location of the environment, in the instability index. The landslide susceptibility map illustrates the risk of landslides by computing landslide factors through a Geographic Information System (GIS). In this study, the instability index was applied to analyze the risk of landslides. DTM and aerial photographs of Chenyulan river watershed were employed. This research considered the landslide susceptibility and the scoring protected targets to estimate the risk of landslides for each sub-watershed in Chenyulan river. The result of this research shows, in the Chenyulan river watershed, Shenmu and Tongfu villages are currently the top priority for setting up a mitigation strategy and regulations.
Key Words : Landslide susceptibility, sub-watershed, protected target, instability index