Hillslope debris flow (HDF) attacks frequently to residents living on the boundary of the plains and terrace near the slope during heavy rainfall events. Knowledge of hillslope debris flow is necessary for disaster prevention. Debris flow events in Typhoon Morakot were studied in this paper. A total of 113 hillslope debris flow torrents, 44 hillslope debris flows and 69 stream type debris flows were investigated according to the unique occurrences and topographic characteristics. Twelve types are proposed to classify the torrents of hillslope debris flow from the stream type debris flows. Finally, a topographic classification model to recognize the hillslope and stream type debris flow torrent is also presented. The model was verified by 75 events from Chi-Chi earthquake with a 92% accuracy ratio.
Key Words : Hillslope debris flow, nature, distinguish model.