基于小流域单元的泥石流易发性评价

Debris Flow Susceptibility Assessment Based on Catchment

为探究不同评价指标体系对泥石流易发性评估结果的影响,选取植被覆盖度、地层岩性、地表起伏度、地表粗糙度、沟壑密度、距断层距离和地震峰值加速度共7个评价因子组成对照组指标体系,通过坡体稳定性分析得到潜在失稳面积与小流域面积比评价指标,构建包括地表起伏度、地表粗糙度、沟壑密度、距断层距离、地震峰值加速度和潜在物源分布面积与小流域面积比的试验组指标体系,采用确定性系数模型,将安宁河流域划分为高、较高、中、较低、低5个泥石流易发性区。对比结果表明:试验组指标体系与对照组指标体系的泥石流易发性高易发区和较高易发区频率比值分别占总频率比值的88.17%和85.88%,表明两种评价指标体系均客观、有效地评价了安宁河流域的泥石流易发性。试验组指标体系的曲线下的面积(area under curve, AUC)达0.767,与对照组指标体系的AUC值相比提升了1.99%,表明泥石流易发性评价指标体系中加入坡体稳定性因子相较于仅考虑孕灾环境因子的泥石流易发性评价结果更好。研究结果为提高泥石流易发性评估结果提供了新思路。

In order to explore the impact of different evaluation index systems on the evaluation results of debris flow susceptibility,seven evaluation factors,including vegetation coverage,stratum lithology,topographic relief,surface roughness,gully density,distance to fault and PGA were selected to form a control group index system.The ratio index of potential instability area to the catchment area was obtained through slope stability analysis.Test group index system including topographic relief,surface roughness,gully density,distance to fault,PGA and ratio index of potential instability area to the catchment area.The certainty factor model was used to assess the susceptibility of debris flow,and the debris flow susceptibility were set as high,relatively high,middle,relatively low and low on Anning River.The results show that the frequency ratio of high and relatively high susceptibility of test group and control group index system on Anning River are 88.17%and 85.88%,respectively.The two evaluation index systems objectively and effectively evaluate the susceptibility of debris flow.The area under curve(AUC)of test group index system is 0.767.Test group index system can improve evaluation 1.99%compared to control group index system.The evaluation result of debris flow susceptibility by adding slope stability analysis factor in the debris flow susceptibility evaluation index system is better than that only considering disaster pregnant environmental factors.It provides a new idea for improving the evaluation results of debris flow susceptibility.