NUMERICAL SIMULATION OF OCCURRENCE FREQUENCY ESTIMATION MODEL FOR DEBRIS FLOWS

This paper deals with the occurrence frequency of debris flow hazard in the areas lack of the accurate rainfall data. It uses numerical simulation and establishes an estimation model of debris flow's occurrence frequency. It is based on the reductionism theory. The model determines the volume of source materials, volume of flood flow and the sediment concentration by volume by employing the source material module and hydrograph module. Then, the interval period of debris flow is confirmed by finding out the most realistic simulation scenario in FLO-2D numerical simulation module. The paper takes Majingzi gully and Xiongjia gully debris flows for instance. They occurred in Shimian county, southwestern China, on 4th July 2013. Their interval periods are all 100 years. It is concluded that this model is able to calculate quantitatively the occurrence frequency of debris flow, and has significant theoretical and practical meaning on early warming and disaster mitigation for catastrophic debris flow.