中国西南山区沟谷暴雨泥石流危险度判定的基本原理和方法

本研究提出了通用于沟谷暴雨泥石流危险度判定的三项基本原理:主次因子原理、因子权重原理和定量赋值原理。首次提出了泥石流危险度的多因子综合定量判定模式和计算公式,为我国西南(西北)山区沟谷暴雨泥石流灾害评估提供了较为先进的实用方法。在云南部分地区的判定检验和应用实践表明,本法具有60%以上的可靠度。可应用于我国西南(西北)山区一切有可能发生暴雨泥石流的自然沟谷和已确认的暴雨泥石流沟谷。

BASIC PRINCIPLES AND METHOD OF JUDGEMENT ON RAIN TYPE DEBRIS FLOW RISK DEGREE IN SOUTHWEST MOUNTAIN RAVINES,CHINA

From the logic deduction,this paper has defined the intension and extension of the de- bris flow risk degree,and distinguished it from the debris flow injured degree.The debris flow risk degree is the damage probability to all things by debris flows within a specific area. The risk degree is a probability concept,and its value is great of equal 0 and less or equal 1.The risk degrss and the injured degree are two different concepts,but the danger degree and the risk degree can be considered as the synonym,as well as the injured degree and the disaster degree also can be considerde as the synonym. Based on the result of expert communication survey,the paper has fixed the maximum volume of a debris flow and the frequency of debris flows as the leading factors for the judgement on the debris flow risk degree,and appplying the related analysis,selected sec- ondary factors for the judgement on the debris flow risk degree.They are:drainage area,main channel length,drainage relative relief,mean slope degree in genesis section, drainage downcut density,main channel winding coefficient,ratio of mud-sand supply sec- tion length to whole channel length,maximum dayly rainfall,annual average rainfall and population density. On the basis of the correlative squence,the weights of these risk factors have been de- termined,and according to the grades of the risk factors,the quantitative calculation formu- late of the debris flow risk degree are obtained.Through the application practices and result tests of the judgement method in Dongchuan Prefecture of Yunnan Province,the method is of about 60% reliability,and it can be commonly applyed to all possible and rainstorm in- duced debris flow ravines in China.