A Precise Prediction Model on Debris Flows Caused by Runoff Mechanism Based on Channel Width and Particle Size

The channel width and particle size in the formation area of debris flow catchment are important factors in the initiation of debris flows caused by runoff mechanism. This phenomenon is often found in the debris flows in strong earthquake area. Up to now, there is no prediction model of debris flow involving these two factors. Based on the 10 min and 1 h precise prediction model of debris flow, this study proposes a revised 10 min and 1 h precise prediction model of debris flow with channel width and particle size by field investigations. The validations were made in the group debris flow events of Dayi, Wangmo County, Guizhou Province, in the group debris flow events of Dechang, Sichuan Province, and a series debris flows in Wenjia Gully located in the Wenchuan earthquake area. The validations were successful in these debris flows events. It is concluded that the particle size in the formation area of debris flow catchment is the geological factor, and the channel width of the formation area of debris flow catchment is one of the topographical factor. Both of them are very important in the formation of debris flows. The revised 10 min and 1 h precise prediction model of debris flows can be used for forecasting of the ordinary debris flows and debris flows in strong earthquake area.