Abstract: Debris flow risk assessment has become a focus and difficult problem. Multiple correlation analysis of several factors about debris flow hazard assessment is carried out based on the infinite irrelevance method, it eliminates information overlap too much. The weights for factors are determined based on using subjective rank correlation analysis (G1 method) to improve objective scatter degree method. Thus a new method for risk assessment of debris flow is obtained. The method is verified by an example including 10 debris flows which combined geology disaster investigation and zoning of Helong City, Jilin Province, and contrasted with the traditional method. The result indicate that the improved scatter degree is easy operated and has advantages comparing with two methods. Four of all debris flow valleys are higher hazard level which close to the critical of traditional method. It can embody difference between the same level hazard in traditional method, and the evaluation results are better in agreement with reality.

Key words: debris, risk, assessment, infinite irrelevance method, improved scatter degree method