横断山区山地灾害的动态风险性评价

对横断山区山地灾害进行科学的动态风险评价,可为区域防灾减灾工作提供重要的科学依据,同时对该区域的社会和谐稳定、经济稳步发展具有重要的现实意义。本文以横断山区为研究区,以五年年际变化为动态变化时间尺度,构建了山地灾害风险动态评价模型。首先选取发育山地灾害的本底因子作为静态危险度评价因子,采用频率比法计算了静态危险度,采用因子叠加法实现了横断山区山地灾害的动态危险性评价;然后选取人口密度、GDP密度和土地利用类型作为动态易损性评价指标,通过简化模型完成了动态易损性评价;最后根据风险评价模型结合动态危险性和动态易损性评价结果,得到了横断山区山地灾害不同年份的风险区划图并完成了动态风险评价。主要结果分述如下:(1)横断山区北部、西北部危险性低,为低和中危险性集中区;南部、东南部危险性高,为高和极高危险性集中区;(2)位于横断山区南部及东北部的高和极高危险区的地区人口较为密集,经济活动性较强,其易损性等级比较高,相应的风险级别同样较高;(3)横断山区受强降雨次数、人口密度、GDP密度和土地利用的动态变化的影响,各年山地灾害的风险性的空间分布范围具有比较明显的差异,横断山区的风险性随时间动态变化。

A Dynamic Risk Assessment for Mountain Hazards in the Hengduan Mountain Region,China

Scientific and dynamic risk assessment of mountain hazards in Hengduan Mountain region can provide an important scientific basis for regional disaster prevention and mitigation and has important practical significance for the social harmony and the steady economic development.In this study,a dynamic risk evaluation model of mountain hazards was constructed with the mountain hazards including landslides,collapses and debris flows taking as research object and the interannual change taking as the time scale of dynamic analysis.Firstly,the background factors affecting mountain hazards were selected as the evaluation factors,and the static hazard degree of the mountain hazards in the region was calculated by using frequency ratio method.on this basis,the dynamic impact of rainfall as main inducing factor was considered,and dynamic hazard assessment was completed by factor superposition method.Then,population density,GDP density and land use types were selected as vulnerability assessment factors,and dynamic vulnerability assessment was completed through a simple statistical model.Finally,dynamic risk assessment of the mountain hazards of Hengduan Mountain region was realized,combined with the results of dynamic hazard and vulnerability assessment results.The results showed that:(1)The high and extremely high-risk areas were mainly distributed in the southern and northeastern parts of the Hengduan Mountain region,where the number of heavy rainfalls was high,and the hazard of the region showed an overall trend of low northwest and high southeast.(2)In the high and extremely high-risk areas of the southern and northeastern parts,the population was relatively dense,and the economic activity was strong,so the vulnerability level of the mountain hazards was relatively high,and the corresponding risk level was also high.(3)The spatial distribution of mountain hazard risk in the region had obvious differences in different year and the risk of the region changes dynamically with time,due to the influence of the dynamic factors such as rainfall,population density,GDP density and land use.