Debris Flow Disaster Research and Threshold Determination of Precipitation Forecast in Danba County

By using the data of debris flow and precipitation in Danba from 2000 to 2020, the debris flow disaster in Danba is studied. The results show that: The Xiaojin River Valley in the northeast of Danba County is a high-prone area of debris flow, and the Jinchuan River Valley in the northwest is a sub-prone area. Debris flow occurs from May to September, relatively concentrates in June to July, and the high incidence period is July. The greater the intensity of short-term precipitation, the greater the risk of disasters, and the period with the highest frequency of heavy precipitation is also the peak period of debris flow, with the period from 19 : 00 to 05 : 00 being the period of high incidence of debris flow disasters. When the precipitation intensity is 10~15 mm / h or 15~25 mm / 3h, there is a certain meteorological risk of debris flow disaster, which is level 4. When the precipitation intensity is 16~ 20 mm /h or 26~35 mm /3h, the disaster risk is the third level. When the precipitation intensity is 21~35 mm /h or 36~60 mm /3h, the disaster risk is high, which is grade 2. When the precipitation intensity ≥ 35 mm / h or ≥ 60 mm / 3h, the disaster risk is extremely high, which is the first level. The longer the effective precipitation accumulation time and the heavier the precipitation are, the greater the possibility of debris flow disaster will be.