Risk Assessment of Debris Flow in Dry Valley Region of Minjiang River Basin Based on GIS

Wenchuan county in Sichuan is located on head of Minjiang, where debris flow takes place frequently. The eruption and distribution of debris flow in this area are influenced by many factors, such as geologic structure, physiognomy, rock kind, precipitation, vegetation, etc. Taking Wenchuan county for example, special data are collected, disposed and analyzed by computer, the risk assessment indexes system and models of debris flow are established based on GIS. After adopting proper appraisable indexes and confirming indexes weight, synthetical appraising value was computed. The results showed that based on synthetical appraising value, probability of debris flow in Taoguangou, Fotangbagou, etc. is great, probability of debris flow in Xinqiaogou, Banzigou, etc. is moderate, and probability in Tanligou, Banqiaogou, etc. is very small. Those accords with historical data can provide reference for preventing and reducing disaster and debris flow forecast.