Abstract:  There is no rapid and satisfactory method to analysis the accumulation area of debris flow as involved complex factors including trigger conditions, provenance, topography and so on. Based on the principle of Laharz, this work proposed a modified statistical model based on the local regional debris flow sample data, and the modified ArcGIS toolbox. Taking Yangjiawan creek, Wuxi County，Chongqing City as an example, this modified Laharz model was used to simulate the debris flow accumulation area under different rainfall return periods. The results show: 1) The fitting accuracy (SSE, RMSE and R2) of Laharz model is significantly improved by modifying the parameters. 2) Based on the DEM and the source volume calculated by field survey, the accumulation ranges of debris flow under different rainfall return periods (10，20, 50,100 a) can be quickly analyzed by using Laharz toolbox in ArcGIS. 3) FLO2D software was used to verify the results of modified Laharz model. The both Laharz and FLO2D basedaccumulation ranges are basically coincident, the error rate of punching distance, accumulation width and area are 10.00 %, 15.00 % and 20.00 % respectively, and the simulation results of Laharz modified model are closer consistent with the field survey results. The modified Laharz model provides a fast and effective method to analysis the accumulation ranges of debris flow, which can provide reference for hazard range prediction of debris flow.

Key words: debris flow, modified Laharz model, accumulation area, rainfall return period