基于GIS的贫困地区降雨诱发型地质灾害风险评估——以湖北省恩施州为例

GIS-based Assessment of Rainstorm-induced Geological Hazards Risk in Enshi Autonomous Prefecture

湖北省恩施土家族苗族自治州(简称恩施州)地处中国14个集中连片特困区之一的武陵山区内,州内少数民族聚居多、贫困人口分布广,地质灾害频发,"因灾致贫、因灾返贫"现象较为突出。本文根据灾害系统学原理和灾害风险分析理论,综合考虑恩施州降雨诱发型地质灾害的致灾因子、孕灾环境和承灾体,构建了降雨诱发型地质灾害风险评价指标体系,基于灾害系统学原理的风险评估模型,对该区的降雨诱发型地质灾害风险进行评估。主要结论如下:(1)降雨诱发型地质灾害的诱发因子为强降雨,恩施州降水丰沛,恩施市中部与鹤峰县东南部属于致灾因子高危险性区域;(2)选取地形地貌、基础地质、水文条件、人类工程活动等孕灾环境要素,耦合信息量法和层次分析法,构建恩施州孕灾环境敏感性评价指标体系,结果表明恩施州孕灾环境敏感性较高、高区域主要分布在巴东县、恩施市和鹤峰县;(3)选取工程建筑、居民人口、社会经济、耕地等承灾体进行脆弱性评估,结果表明承灾体脆弱性较高区域与人口集中地区在空间上重合,利川市和来凤县有更多的高脆弱性区域;(4)综上可知,恩施州的降雨诱发型地质灾害风险总体较高,其较高、高风险区域主要分布在巴东县和恩施市。

Rainstorm-induced geological disasters happen frequently in recent years and cause great loss in some regions of China. Enshi Autonomous Prefecture which located in Wuling Mountain Region is one of the fourteen Continuous Extremely Poverty Areas（CEPA） in China. The region is characterized with more frequent geological disasters, large amount of minority population and wide range of poor people distribution. Rainstorm-induced geological disaster threatens the communities usually, which pushes the people into a worse condition. Based on the theory of disaster system and natural disaster risk assessment, the rainstorm-induced geological disaster risk indicator system about Enshi Autonomous Prefecture was established considering the hazard affected bodies, hazard-formative environment and hazard bodies of this region. A comprehensive risk assessment model system is constructed and the sensitivity, vulnerability and risk of the rainstorm-induced geological disaster hazard in Enshi Autonomous Prefecture were explored at a l km × l km scale. The results are concluded as follows：（1） The inducing factor of the disaster is heavy rainfall, and the high hazard mainly occurs in the central of Enshi city and the southeast of Hefeng county.（2） By applying the Information Value Method and Analytical Hierarchy Process（AHP）, the hazard-formative environment sensitivity evaluation index system was set up, including the topography, geomorphology, basic geology, hydrology and human activity. The less high and high sensitivity areas are mainly distributed in the Badong county, Enshi city and Hefeng county.（3） The building construction, population, social economy, arable land were selected for vulnerability assessment of hazard-affected bodies, and Lichuan city and Laifeng county were concluded to be occupied with more high vulnerability areas.（4） Rainstorm-induced geological disasters risk in Enshi Autonomous Prefecture is high according to the sensitivity and vulnerability assessment, and the areas having the highest risk mainly distributed in Badong county and Enshi city, which is consistent with the actual situation.