Water Resources and Power

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.