DEMs(digital elevation models) are generally used to automatically map the channel network and to delineate subbasins. At present, most DEM data are derived from three alternative sources which are ground survey, pphotogrammetric data capture and digitized cartographic data sources. The accuracy of a DEM is dependent on the spatial resolution, quality of the source data, collection and processing procedures, and digitizing systems. weather conditions and nature environment.etc provide us satellite image of the highest quality. However, Match in error of the auto generation DEM was severely affected by physical and environmental conditions at shooting time. This paper shows that real-time operation analysis of applied hydrology after extracting DEM Using a pair of Kompsat images.