Study on the development characteristics of post-fire debris flow and its early warning risk aversion in Zhongba Village, Xide County

On May 7, 2020, a forest fire broke out in Zhongba Village, Luji Township, Xide County, Liangshan Yi Autonomous Prefecture, Sichuan Province, covering an area of about 6.7 km². After the forest fire, the ash on the slope was about 2～6 cm thick, and the surface soil structure was disturbed. Under the heavy rainfall of about 20 min in the evening of June 4, the post-fire debris flow disaster broke out in the four gullies at the back mountain of Zhongba Village, which is a great threat to the 164 residents of 41 households in the gully mouth. Through remote sensing interpretation and field investigation, the fire intensity and deposit distribution characteristics of four gullies in the burned area are identified, the development characteristics of post-fire debris flow in Zhongba Village, Xide County are analyzed, and the risk assessment is carried out. Based on the real-time rainfall data obtained from group survey and group prevention, a set of early-warning and risk avoidance scheme for debris flow in mountain areas after fire is proposed, which has been verified by this example.