基于GIS的武陵山区洪水灾害风险评估

武陵山区是我国14个集中连片特困区之一，跨省交界面大、少数民族聚居多、贫困人口分布广，该区域内洪水灾害频发，使得"因灾致贫、因灾返贫"现象较为突出，对区域经济发展造成较大的阻力。本文基于灾害系统学原理，构建了适合区域成灾特点的风险评估指标体系，采用风险评估模型，对武陵山区洪水灾害风险进行评估。研究结果表明：尽管区域洪灾易发，但承灾体脆弱性较低，致使武陵山区洪水灾害风险等级全区总体水平较低，高风险区呈东北-西南向条带状分布，从东南向西北，依次有：东南部的涟源市、冷水江市、新化县、隆回县、邵阳县、洞口县、武冈市高风险区；中部的石门-慈利-沅陵-芦溪-辰溪-溆浦-麻阳-芷江一线高风险区，西北部的丰都-石柱西北部高风险区。

GIS-based flood disaster risk assessment in Wuling Mountain Region

Abstract: Flood disasters happen frequently in recent years and causes great loss in parts of China. Wuling Mountain Region is one of fourteen Continuous Extremely Poverty Areas (CEPA), across three provinces and one municipality city (respectively is Hubei Province, Hunan Province, Guizhou Province and Chongqing City). The region is characterized with large minority population and wide poor people distribution, where annual precipitation is between 730 and 1260mm, and flood disasters occur frequently. The flood disaster threatens the communities usually, which pushes the people in worse condition. Based on the natural and social conditions, the resistance of economic development is relatively large, for the outstanding phenomenon of "disaster induced poverty and disaster recurrent poverty" in this region. In this paper, on the basis of disaster system theory, flood disaster risk indicator system was established in the varied topography and poor people wide distribution mountainous area. The flood disaster risk indicator system divided into three main components, namely hazard indicator (H), sensitivity indicator(S) and vulnerability indicator (V). In the indicator system, precipitation was driving factor of flood, belonged to hazard indicator(H), terrain, river system, soil and resistance ability were factors for flood redistribution, belonged to sensitivity indicator(S), population, crops and buildings were belonged to vulnerability indicator(V). According to geographical information system (GIS), some counties in the middle eastern of study area had higher hazard level for strong rainfall. The hazard environment was complex involving seven factors, and the result showed the higher sensitive area was in band from northeastern to southwestern. And the vulnerability was in different pattern from hazard and sensitivity, the higher sensitive areas were located in eastern and western, and the lower areas was seated on the middle part of the region. Applying risk assessment model based on flood disaster hazard, environment sensitivity, resilient society vulnerabilities, different hazard bearing bodies' and integrated risks caused by flood disaster were computed in Wuling Mountain Region. The results indicated that the study area risk level was relatively lower, and the total area of low and lower risk levels was up to 85.63%. The high risk areas were in bands distribution from northeast to southwest in the study area. There are three bands from southeast to northwest, respectively is southeast region(including Lianyuan City, Lengshuijiang City, Xinhua County, Longhui County, Shaoyang County, Dongkou County and Wugang City), central strip region(including Shimen County- Cili County- Yuanling County- Luxi County- Chenxi County- Xupu County- Mayang County- Zhijiang County), and northwest region(including Fengdu County and Shizhu County northwestern). This result was similar to the previous study on the scale of whole country. The pressures of regional poverty alleviation and disaster reduction are large because of the regional feature, although total flood disaster risk level is comparatively low. The results of this study will be useful in the poverty alleviation practice and regional natural disaster risk management. The next important work will focus on action mechanism between natural disaster risk and regional poverty, which will be an interesting achievement for guidance the poverty reduction, medium-term/ long-term programs and regional development.