基于流域单元的岷江上游泥石流危险性评价

泥石流的形成需要具备高陡的地形、充足的水源以及丰富而松散的固体物源三个基本条件，当山区小流域具备上述条件时，都有发生泥石流的可能。选取岷江上游区域作为研究区，以数字高程模型（DEM）作为基础数据，运用均值变点法和河网密度法结合遥感影像，实现研究区内小流域划分；针对影响泥石流形成的三个基本条件，以小流域作为评价单元，选取地层岩性、断裂密度、平均坡度、形状系数、沟道比降、24 h最大降雨量等六个评价指标，应用主成分分析法计算各因子的权重，实现岷江上游地区的泥石流危险性评价。分析结果表明，评价的结果能较好的反映出岷江上游的泥石流灾害分布情况，为该区泥石流灾害的防治提供了参考和依据。

Assessment on the Hazard of Debris Flows in the Upper Min River Based on the Watershed Catchment-Unit

There are three conditions of the debris flow on formation including topography, geology and precipitation. Where there are formation conditions of debris flow, there is possible for the debris flow occurrence. We chose the upper Min River as study area, took the digital elevation model(DEM) as the basic terrain data, used the mean change point method and drainage density method combined with the remote sensing image, and got the distribution of drainage area. And we calculated topographic factors of each drainage area, such as lithology, the density of fracture, average slope gradient, and degree of watershed development, channel gradient and 24-hour rainfall of each valley. Using the principal component analysis, we identified the potential sites of debris flows in the upper Min River. According to the analysis result, the evaluation results can reflect the distribution of debris flow of the upper Min River, which can provide guidance and reference for disaster prevention in this area.