CAUSES, CHARACTERISTICS AND HAZARD ASSESSMENT OF THE DEBRIS FLOWS IN LONGXI RIVER BASIN, SICHUAN PROVINCE

Under the influence of the Wenchuan Earthquake, debris flows have taken place in a total of 45 gullies in Longxi River Basin by 2011, causing heavy economic and property losses. The landform, precipitation and provenance are studied based on the field investigation of debris flow disasters. It is believed that the latter two are the main causes for debris flows in the area. The debris flows are characterized by group occurrence, small river basin outbreak, structural belt coupling, huge destructiveness and disaster chain. The MFCAM model is used for the hazard assessment of debris flow gullies. The results show that there is one gully with high risk, 14 with moderate risk and 30 with low risk in the area.