不同降水频率下淮河流域洪涝灾害风险评估

流域洪涝灾害风险评估是保证地区安全和可持续发展的重要前提,为探讨不同降水频率下淮河流域的洪涝灾害风险变化,结合洪涝灾害的形成和影响因子,建立了包括洪涝危险性、暴露性和脆弱性的指标体系,采用层次分析法及加权综合法构建了暴雨洪涝灾害风险评估模型,实现了洪泽湖以上的淮河中上游区域洪涝风险的定量评价和区划。结果表明,洪涝灾害多发于淮河中上游干流蓄洪区,中高风险区集中分布在流域中部,低风险区分布在流域北部及北部偏西。随着降水频率的增加(12.5%～62.5%),最大日降水量在东部逐渐降低,西南部呈现增加趋势,其高值区由南向北移动;由于脆弱性和暴露性的影响加强,不同降水频率综合风险区划变化表现为风险高值区面积占比先降低后增加,由5.1%减至2.8%又增至15.1%,风险中低值区逐渐转变为中高值区,中低值区面积占比由34.8%减至22.6%,中高值区由28.1%增至35.6%;总体呈现"东部遇水小灾,西部及南部高值区遇涝大灾,北部及北部偏西较安全"的空间分布变化格局。研究结果可为淮河流域的暴雨洪涝防灾减灾工作提供一定的参考价值。

Risk Assessment on Flood Disasters of Different Precipitation Frequencies in Huaihe River Basin

It is very important for a basin to guarantee its regional safety and sustainable development by doing a risk assessment on flood disasters. In this study, the precipitation frequency was introduced to the risk assessment in the upper and middle reaches of the Huaihe River Basin above the Hongze Lake. The evaluation index system was established by considering the factors that have impacts on the formation or prevention of the flood disasters. The dangerousness, the exposure and the vulnerability in the system were the 3 levels needed to be processed by the analytic hierarchy process (AHP) and the weighted integrated method. The spatial analysis technology was used to do the quantitative risk assessment and zoning on flood disasters. The results show that the high risk areas of flood disaster are located in the flood storage area in the upper and middle main stream. The moderate high risk areas are concentrated in the middle of the basin, and the low risk areas are distributed in the north and west north of the basin. With the increase of precipitation frequency (12.5% 62.5%), the high value areas of the maximum daily precipitation move from the south to the north and there is a decreasing risk in the East while an increasing risk in the southwest. In addition, the risk zoning in different precipitation frequencies shows that the proportion of high risk areas has a fluctuate increase from 5.1% to 2.8% and then to 15.1%, as impacts of the vulnerability and the exposure are strengthened. And the moderate low risk areas, with the proportion decreasing from 34.8% to 22.6%, are gradually changing into moderate high risk areas, with the proportion increasing from 28.1% to 35.6%. In general, the spatial distribution presents that there is a relatively small chance of flood disasters in the east but a big likelihood of flood disasters in the east and south, and it is safer in the north and the west north. The results can partly provide reference for regional flood prevention and mitigation in the Huaihe River Basin.