Risk analysis of flood disaster in Shanghai Municipality

This paper analyzes spatiotemporal distribution of flood disaster in suburb of shanghai Municipality according to the historical data from 1949 to 1990. Since planning for water resources development carried out in 1979, the index of area damaged by flood disaster has decreased significantly. In all districts and counties of the municipality, considering two factors of flood disaster frequency ratio and area ratio, Nanhui District is the highest. Because the historical data of flood disaster is not enough to be used for analysing the probability distribution, the information diffusion method was introduced to change single sample observations into fuzzy sets, and a quantitatively analyzing model of flood disaster risk was proposed. The results show that the flood disaster risk assessment values are higher in Nanhui District and Pudong District when the index of area damaged by flood disaster is lower, However, the flood disaster risk assessment values in Chongming, Jinshan are always high in any case. When the index reaches 0. 8, the exceedance probability are 0.03345 and 0. 01243, corresponding to 30-year return period and 50-year return period respectively.