台风暴雨型泥石流单沟危险度研究

摘要

台风暴雨型泥石流分布广泛并常造成重大灾害,有必要对其危险度进行研究.选取温州山区的14处典型台风暴雨型泥石流为研究对象,构建了基于组合因子的单沟泥石流危险度评价模型.选取泥石流规模(M)、泥石流频率(F)、冲沟纵比降(J)、形成区完整系数(C)、台风降雨综合值(E)和地质综合因子(G)来表征泥石流危险程度,并基于信息熵理论获得各组合因子权重值.针对研究区均为低频泥石流的特点,引入麦尔登比率(R值)以间接确定基于不同R值范围的泥石流爆发频率(F).将评价模型应用于所选的典型沟谷,得到各沟谷泥石流危险度,评价结果符合研究区泥石流沟谷为中、小型低频泥石流的实际情况,并且评价为危险度高的沟谷具备区域上最易形成泥石流的地质地貌条件.%Typhoon-triggered debris flow widely occurs and often causes major disasters,and it is necessary to study its hazard degree.Taking 14 typical typhoon-triggered debris flows in the Wenzhou mountain area as examples,this paper establishes a hazard assessment model of a single gully based on combinatorial factors.Debris flow scale (M),debris flow frequency (F),gully gradient ratio (J),forming region integrity coefficient (C),comprehensive typhoon precipitation value (E) and comprehensive geological factor (G) are selected as combinatorial factors to represent the debris flow hazard degree,and the weights of combinatorial factors with the entropy method are obtained.As the gullies in the study area are low frequency as to debris flow,this study uses the Melton ratio (R) to indirectly determine the frequency (F) of debris flow on different scales of R.The hazard assessment model is applied to the selected gullies,and the hazard degrees are obtained.The results correspond to the actual reality that debris flows in the study area are of low frequency and of middle and small scale,and the gullies assessed as high hazards possesses the geological and geomorphological conditions which is the most debris flow-prone in the region.