泥石流致灾因子敏感性分析——以四川都江堰龙溪河流域为例

泥石流是我国山区常见的地质灾害,为了定量研究泥石流灾害致灾因子的敏感性并确定各个致灾因子的权重大小,本文通过野外调查、数理统计法和层次分析法对龙溪河流域泥石流灾害的主要致灾因子进行定性规律分析和定量权重计算。结果表明:(1)泥石流灾害的发生与致灾因子的敏感性区间主要定性表现为:流域面积小于1 km²以内、高差在200～400 m范围内、距断层距离为0～2 km、山坡坡度30°～50°、岩性为砂岩、纵比降在400‰～600‰等,其泥石流发生与致灾因子具有相关性,且相关性较好;(2)选取了泥石流灾害致灾因子中的历史因子、地形因子、地质因子和降雨因子等4个一级因子以及流域面积、高程、相对高差、纵坡比、地层岩性等14个二级因子建立层次分析模型和计算判断矩阵,定量计算权重值得出降雨,流域面积,地层岩性,纵比降等四个因子对泥石流发生的敏感性最强。这一结论具有普遍性,可对该区域泥石流的易发性,危险性,风险性评价提供一定的数据参考意义。

Sensitivity analysis of debris flow to environmental factors: a case of Longxi River basin in Dujiangyan,Sichuan Province

Debris flow is a common geological hazard in mountainous areas. In order to quantitatively study the sensitivity of disaster-causing factors of debris flow and determine the weight coefficient of each hazard factors. The field investigation, mathematical statistics and analytic hierarchy process were used to study qualitatively and quantitative weights of hazard-causing factors in Longxi River Basin. The results show that:(1) the qualitative analysis between the occurrence of debris flow disasters and the susceptibility factors of hazards are as follows:the watershed area is less than 1 km2, the height difference is within 200 to 400 m, the distance from the fault is 0 to 2 km, and the slope of the slope is 30°~50°, the lithology is sandstone, the vertical ratio drops between 400‰ to 600‰, etc., the occurrence of debris flow disasters is well relevance to its main disaster-causing.(2) Four primary factors, including historical factor, topographic factor, geological factor and rainfall factor, as well as 14 secondary factors, such as watershed area, elevation, relative elevation difference, longitudinal slope ratio and stratigraphic lithology, are selected to establish the analytic hierarchy process model and the calculation judgment matrix. Obtains the weight value of disaster-causing factors on debris flow occurrence, which indicates that the four factors of rainfall, watershed area, stratigraphic lithology, and aspect ratio are the most sensitive to debris flow occurrence. This conclusion provides some data reference significance for the susceptibility, risk, and risk assessment of debris flow in the region.