In spite of many numerical analysis of debris flow, a little information has been found out. In this paper the watershed is divided to apply rainfall runoff and to estimate debris flow integrating flow and soil article. We use the contour data to extract spatially distributed topographical information like stream channels and networks of sub-basins. A Quasi Digital Elevation Model (Q-DEM) is developed, integrated, and adopted to estimate runoff based on marked one. As a results, it has been found out that the debris flow was close to observed flow hydrograph. Because debris flow is finished in 30 second, it is important that we have to prepare its prior countermeasure to minimize the damage of debris flow. The GIS-linked model will provide effective information to plan river works for debris flow.