The Flood Risk Analysis of Taihu Lake Basin under the Simultaneous Encounter of Taihu Lake High Water Level, Typhoon Rainstorm and High Tide Level

Taihu Lake Basin is composed of a complex and dense river network. Because of its characteristics of natural geography and climate, high water level, typhoon rainstorm and high tide level often lead to flood disasters. It will be very important to make flood control operation schemes of Taihu Lake Basin by the flood risk analysis and evaluation under the extremely unfavorable circumstance of simultaneous encounter of high water level, typhoon rain and high tide level. In this paper, based on the further processing and generalization of the river network and units, HOHY2 model is improved by adding the calculation of overtopping. And then the flood risk of Taihu Lake Basin is calculated and analyzed in the case of focusing consideration on high water level, typhoon rainstorm and high tide level. There are 36 flood schemes in this research, which are calculated about the superposition floods of different high water levels, typhoon rainstorms and high tide levels. For example, one of the most disadvantageous conditions is calculated on high water level of 5.20m, typical typhoon rainstorm in 1962, high tide level of 9.83m. The results show that under the condition of the superposition the proportion of the submerged area, which water depth is within the scope of 1.0m-2.0m, is 2.86% in Taihu Lake Basin. In the case of encountering these three factors, the biggest one influencing the flood risk is typhoon rainstorm, followed by high water level and high tide level. And the results of this research are of great significance to flood control and disasters reduction in Taihu Lake Basin. It is further demonstrated that the precision and reliability of this improved HOHY2 model is high. And there is very important value to promote this improved model in the basin flood risk analysis.