大别山北坡典型区域暴雨洪涝风险评价研究——以安徽省六安市为例

ASSESSMENT OF RAINSTORM FLOOD RISK IN LU'AN CITY ON THE NORTH SLOPE OF DABIE MOUNTAIN

从暴雨洪涝的形成机制入手,考虑致灾因子危险性、孕灾环境敏感性、承灾体易损性和防灾减灾能力等4个因子的综合作用,针对安徽省六安市实际,构建了暴雨洪涝风险评价指标体系。借助ArcGIS 10.0强大的空间分析功能,以30m×30m栅格为评价基本单元,在4个因子空间分布图的基础上,依据层次分析法确定的权重,进行因子叠加分析,得到了暴雨洪涝风险综合评价结果和等级图。结果表明,六安市暴雨洪涝风险明显分为西南、东北两部分,西南大别山地区整体风险水平低于东北部。从县域来看,六安市城区、寿县整体风险水平最高。从自然区域来说,高风险区主要分布在河流沿线、湖泊周边和圩畈区。初步验证表明,风险评价结果符合实际情况,具有较好应用价值。

Lu'an city is situated on the north slope of Dabie Mountain.As a subtropical monsoon climate zone,the spatial and temporal variation of precipitation is obvious in this city.It suffers from heavy rainstorm and flood disaster frequently especially in the flood season.Analysis on rainstorm flood risk is of great importance for taking precautions and fighting against flood disasters in Lu'an city.According to the principles of risk assessment for natural disasters,an assessment model on Lu'an rainstorm flood risk was built including 4 factors:the risk of disaster causing,the sensitivity of disaster environment,the vulnerability of disaster-bearing bodies and the ability of disaster prevention/reduction.Main data used in the research includes daily precipitation data from 6 meteorological stations in Lu'an city from 1956to 2011,DEM in 30mresolution,spatial distribution maps of the water systems and lakes of the research area.Besides this,we also make use of total acreage,population,GDP as well as the acreage under cultivation of villages and towns in Lu'an city.With the support of ArcGIS10.0,using 30m×30mraster as basic assessment unit,we ranked each influencing factor according to the mean and standard deviation and then defined affecting degree for each grade.The map of rainstorm flood disaster risk division in Lu'an city was created ultimately by overlaying raster coverage of the influencing factors,and the weights of which were determined through the Analytic Hierarchy Process(AHP).Results show that the rainstorm flood risk in the southwest is in general different from that in the northeast.Although the annual precipitation is abundant and heavy rainstorm occurs frequently in the southwest,the rainstorm flood risk in this area is lower than that in the northeast because of its low population density and low per capita GDP resulted from mountain area of high altitude.The highest possibility of flood risk is found in Lu'an and Shouxian town.On shores of rivers and lakes as well as depressions,the rainstorm flood risk is relatively high.Using the flood disaster during summer in 1991to test and verity,the evaluation solution is consistent with the actual situation.The formation of rainstorm flood disaster is a complex system and the influencing factors are numerous.It's of certain difficulty to assess rainstorm flood risk quantitatively completely. Further explore is necessary in the follow-up study.