Shanghai Extreme Storm Flood Socio-economic Risk Analysis

Shanghai is a typical estuary delta city,has a high density of assets and population,and faces a rising flood risk.In the future,with climate change,sea level rise,urban expansion and other climatic and non-climatic factors,the frequency and severity of extreme floods will continue to increase.Extreme storm floods have caused serious social and economic losses in Shanghai,Therefore,the analysis of Shanghai's asset values and population losses is great significance for effective response to disaster risk management and climate change adaptation.This study is based on the data of multiple extreme storm floods of 1/200-year,1/500-year,1/1000-year and 1/5000-year in Shanghai under current and future emission scenarios,using Arc GIS software,combined with GDP data,population and other data,considering population and different lands use the loss rate of assets under different submergence depths to quantify the exposure and loss of Shanghai's assets and population.The main research work and conclusions are as follows.(1)Analyzed the social and economic exposure and losses under extreme storms and floods in the current scenario.In 1/200 year,the exposed and lost assets in Shanghai were 552 billion yuan and 19.8 billion yuan,and the exposed and casualty were 280 thousand and 299,respectively.In 1/5000-year,the exposure and loss of asset are7.7times and 16.9times that of 1/200-year,which are 4248.6 billion yuan and335.8billion yuan,respectively.The population exposure and casualties were 8.8 times and 3.5 times tant in 1/200-year,which were 2.42 million and 1045 people,respectively.Areas with higher exposure assets per unit area are mainly located in central Shanghai and Pudong,and areas with higher population exposure are mainly located in central Shanghai and Songjiang.(2)Analyzed the loss of Shanghai in the extreme storm flood under the current scenario,calculate the annual expected damage,and a hotspot analysis of the previous year's expected loss in space.By integrating the risk curve,the annual expected loss of total assets is 545 million yuan,of which the annual expected damage of residential land and public facility land accounts for a larger proportion,225 million yuan and 126 million yuan respectively.The annual expected damage spatial distribution pattern is similar to that of neighborhood committee-scale hotspots.The hotspots of loss are mainly distributed in the center of Shanghai,the north bank of Hangzhou Bay,the Qingsong depression in the southwest,and the river mouth near Wusongkou.Calculate the expected annual casualties of the population,and calculate the expected annual casualty population of Shanghai by integrating it to 2.28 people.(3)Analyzed the exposure and loss of Shanghai's assets and population in 2050 under different storm flood scenarios in the background of sea level rise in the future,and analyzed the expected annual damage for hotspots.In 1/200-year,the exposure in the RCP8.5 high-end scenarios is higher than the RCP8.5 and RCP 4.5 scenarios.In1/5000-year,the most exposure assets under the RCP4.5 scenario.Under the 3 emission scenarios,the exposed assets during the 1/5000-year are 4.3,4.0 and 3.6 times that of200 years,respectively.The distribution pattern of its exposed assets is similar,with the high exposure areas of assets mainly located in the center of Shanghai,Pudong and part of Songjiang.The RCP8.5 high-end scenario has the highest number of exposed population,with 12.1%,12.2% and 12.5% of the total population of Shanghai under1/5000-year scenario,respectively.The loss analysis found that the exposure of assets under the 3 scenarios shows a continuous distribution as the return period increase.Asset losses in the 1/5000-year are all close to 4 trillion yuan,which are 8.1 times,6.9 times,and 6.0 times the losses in 1/200-year respectively.As the return period increase,asset losses grow faster than exposed assets.The annual expected loss was calculated by integrating the disaster loss with the annual probability of exceeding the disaster.Among them,the annual expected loss under the RCP8.5 high end scenario is the highest,and the difference is 1.46 billion yuan from the lowest annual expected loss under the RCP4.5 scenario.Analyze the hotspot pattern of the annual expected loss under the RCP8.5 high end scenario,in the center of Shanghai and the Huangpu river,it is the hot spot of loss.