FUZZY COMPREHENSIVE EVALUATION OF DEBRIS FLOW RISK BASED ON PROBABILITY COMBINED WEIGHT

摘要

This paper proposes a probability-based com-bined method due to the subjective influence of the weight assignment process in the risk assessment of debris flow. The weight is regarded as a bounded uniform random variable, and the boundary is deter-mined by the equal weight method, the maximum deviation method, and the entropy method. The op-timal weight is obtained through the Monte Carlo simulation and used as the weight set of the fuzzy comprehensive evaluation (FCE) model. According to the formation characteristics of debris flow in Beichuan County, the loose source material reserves, the basin area, the drainage density,the basin relative relief, the shifting bed proportion, and the main channel length are selected as fuzzy factor sets. The fuzzy vector B calculated by the judgment matrix F is used to evaluate the risk of 72 debris flows in Beichuan County, Sichuan Province according to the maximum membership principle. The results show:1)probability-based combined method is a more rea-sonable method of weight determination;2)there are 33 debris flows with a high degree of danger, and Beichuan County is still facing the threat of debris flow disasters; 3)the risk degree of Xishanpogou, Yuxuegou, Subaogou and Wangjiayangou are higher than those of the method proposedby Liu and Tang. A higher assessment level is more reasonable be-cause considering the distribution of buildings in the basin.