基于沟域单元的康定市泥石流易发性评价

Susceptibility assessment of debris flow based on watershed units in Kangding City,Sichuan Province

为研究康定市泥石流易发性,将康定市划分为421个沟域单元,采用ArcGIS软件中空间分析工具以及SPSS软件分别对评价指标内部叠加情况、评价指标与泥石流灾害相关性进行了分析,通过筛除剔除重叠度高、相关性差的评价因子,选取流域面积、melton比率、形状系数比、流域崩滑密度、流域植被覆盖率、流域道路密度、流域平均径流侵蚀力指数、多年汛期平均降雨量等8个评价指标进行康定市泥石流地质灾害易发性评价。采用信息量模型与熵值法相结合的方法定量评价了泥石流易发性,熵值法定量确定了评价指标权重,计算出评价因子加权信息量值,将康定市泥石流划分为极高易发区、高易发区、中易发区以及低易发区4个等级。通过频率比模型、受试者工作特征曲线(ROC曲线)对泥石流易发性评价结果进行检验,ROC曲线AUC值为0.842,表明评价模型精度较高。

To study the susceptibility of debris flow in Kangding City,the study area was divided into 421 watershed units.Spatial analysis tools in ArcGIS software and SPSS software were used to analyze the internal superposition of evaluation indicators and the correlation between evaluation indicators and debris flows disasters.By screening out the evaluation factors with a high degree of overlap and poor correlation,eight evaluation factors were selected for debris flow susceptibility assessment.These included watershed unit area,melton rate,form factor ratio,collapse and landslides density of catchment,average fractional vegetation cover of catchment,road density of catchment,average stream power index of catchment,and average rainfall during the multi-year flood season.The susceptibility of debris flow was quantitatively evaluated by combining the information value model and the entropy method.The weights of the evaluation indicators were quantitatively determined by the entropy method,and the evaluation factor weighted information quantity value was calculated.Based on this,the debris flow susceptibility in Kangding City was divided into four grades:extremely high,high,medium and low.The results of debris flow susceptibility assessment were tested using the frequency ratio model and the Receiver-Operating Characteristic(ROC)curve,with an AUC curve of 0.842,indicating high accuracy of the evaluation model.