横断山区泥石流空间格局和激发雨量分异性研究

地形、降雨等环境因子决定了泥石流的时空分布特征,理解泥石流与这些因子的关系有助于区域泥石流灾害风险评估与防灾减灾工作。以横断山区为研究区域,选取降水、气候、地貌、地质、土地覆盖、土壤厚度、高差势能以及湿度指数等因子,利用地理探测器和灰度关联分析等方法,探讨了环境因子与泥石流沟空间分布的关系以及降水特征与泥石流灾害的时间关联性。结果表明,湿度指数是决定泥石流沟空间格局的最主要因子,其次是高差势能和土壤厚度,多年平均分布的降水特征对泥石流沟分布的影响较小。泥石流灾害事件与降水特征的时间关联具有较大的区域异质性。泥石流发生地的激发雨量、湿度指数、高差及土壤厚度的统计分布在不同地貌、地质和气候单元中有明显差异。这表明泥石流预警不仅需要考虑雨量等激发因子,还必须考虑其他影响因素的空间差异性。

Spatial pattern of debris-flow catchments and the rainfall amount of triggering debris flows in the Hengduan Mountains region

Environmental factors determine the spatial and temporal distribution of debris flows. Understanding the relationship between debris flows and their effective factors is important for debris flows risk assessment at regional scale. In this paper, geographic detectors and gray correlation analysis are used to explore the relationship between 11 influencing factors, including precipitation, climate, landforms, geology, land cover type, soil thickness and topographic wetness, and the spatial distribution of debris flows-prone catchments, as well as the spatial and temporal correlation between precipitation and debris flows disasters in the Hengduan Mountains region. The results show that the topographic wetness index is the most dominant factor controlling the spatial distribution of the catchments, followed by topographic relief and soil thickness. Temporal correlation between debris flows disasters and precipitation characteristics has large regional heterogeneity. The rainfall characteristics of debris flows disaster events in different regions exhibit significant difference. The frequency of debris flows with rainfall, topographic wetness, topographic relief and soil thickness in the Hengduan Mountains region varies significantly in different zones, which indicates that not only the rainfall but also the other factors controlling the spatial pattern of debris flows should be reflected in debris flows early warning model in the region.