基于GIS的汉江上游安康市洪水灾害风险评价

Flood Disaster Risk Assessment of Ankang City in Upper Reaches of Hanjiang River Based on GIS

位于汉江上游秦巴山区的安康市,历来洪水灾害频发且洪灾损失严重。本研究根据洪水灾害系统理论,基于GIS和层次分析法(AHP),从形成洪水灾害的危险性和易损性两方面出发,对安康市的洪水灾害风险进行了评价。在洪灾评价过程中,选取安康市近50年降水量、降水变率以及地形高程、坡度、水系等自然因素指标进行洪灾危险性评价,选取安康市人口密度、GDP密度、单位面积年粮食产量等经济因素指标进行洪灾易损性评价。首先通过层次分析法确定各评价指标权重,然后运用ArcGIS的地图代数功能对安康市洪水灾害危险性和易损性进行叠加分析,得到了安康市洪水灾害风险评价结果。结果表明:安康市洪水灾害风险主要集中在汉江沿岸,且以河流干流为中心逐渐向两边支流递减。该评价结果与安康市2010年"7.18"洪水受灾情况基本一致,说明该评价方法可行。本研究结果可为安康市制定合理的防洪减灾规划,减轻洪灾损失,提供重要的科学依据。

The flood disaster has occurred frequently with serious losses in Ankang City,which locates in Qinba mountain areas in the upper reaches of Hanjiang River. According to the theory of flood disaster system,based on GIS and AHP,the flood disaster risk assessment on Ankang City was studied from the hazard and vulnerability of flood disaster. The natural factor indexes,including annual rainfall and precipitation variability in nearly 50 years,terrain elevation,slope and water system of Ankang City,were considered to analyze the flood hazard. The economic indicators,such as population density,GDP density and annual grain output per unit area,were selected to analyze the flood vulnerability. Then the AHP method was used to compute the weights of evaluation indexes,and the grid of Arc GIS was used to overlay the hazard and vulnerability of flood disaster. The results of flood disaster risk assessment for Ankang City was obtained. The results showed that the flood disaster risk of Ankang City concentrated mainly along the Hanjiang River,and decreased generally from the main stream to the branches. The results were in consistent with the ＂7. 18＂flood events in 2010,which showed the feasibility of the evaluation method. Meanwhile,the results could provide an important scientific basis for the reasonable flood control and disaster mitigation planning for Ankang City.