Debris flow forecasting test based on a physical model coupling with a distributed hydrological model

In this paper, a physically-based debris flow model, coupled with a distributed hydrological model, is developed for regional debris flow forecasting test. The debris flow basins, obtained by using potential debris flow basins identifying method, are taken as forecasting units. GBHM distributed hydrological model is applied for hydrological processes simulation during debris flow occurring. Based on the infinite slope model, the slope stability is determined by the safety factor. The density of water-soil mixture with basin runoff and unstable soil volume is applied for the regional debris flow forecasting. The model is implemented and evaluated in Yunnan province, where heavy rainfall triggered debris flow on 24 June 2016. Results show that the forecast model successfully predicts two-thirds of debris flow disasters in this process, and has a high accuracy of prediction and strong applicability.