Extreme Flood Risk Assessment Of Residential?Commercial?Office And Industrial Buildings In Shanghai

In the context of global warming and the increasing occurrence of global meteorological and hydrological events,natural disasters are increasingly becoming a serious threat to social and economic development.Shanghai is a coastal lowland city with developed industrial economy and highly concentrated population and economy.With the rapid socio-economic development of Shanghai,a large number of capital and population influx,urban construction land rapidly increased.At the same time,with the increasing frequency and harm degree of flood disaster,extreme flood disaster will cause huge direct economic loss and indirect influence on urban construction in Shanghai.Therefore,the spatial relationship between the value distribution of buildings in Shanghai and the submersion depth and scope of extreme flood disasters is of great significance to effectively reduce the economic losses caused by flood disasters.Flood risk assessment of buildings in Shanghai is helpful to formulate disaster prevention and mitigation measures and policies for buildings.This study is based on the depth and scope of composite storm flood under four return periods of 200,500,1000 and 5000 years in Shanghai.Through the classification of grid computing,to extract the different return period flood depth map,combining with the building footprint and height,construction cost of residential,commercial,office,industrial building and the reference loss rate of foreign residential,commercial,office and industrial building in different submerged depth interval,using the method of geological statistics and GIS combined four return period in Shanghai of four types of buildings under exposure value and quantify the loss of value.The main research work and conclusions are as follows:(1)Analyze the spatial distribution pattern of the value of four building types in Shanghai.The value of residential buildings in Shanghai was the highest in 2017,accounting for 47% of the city's total floor area,with construction value of about 500 billion CNY.Industrial buildings,accounting for 17% of Shanghai's total floor area,are worth about 1 trillion CNY.Office buildings,accounting for 9% of the total floor area in Shanghai,are worth about 120 billion CNY.Finally,commercial buildings,accounting for 3% of Shanghai's total floor area,are worth about 500 billion CNY.(2)Exposure distributions of residential,commercial,office and industrial buildings in Shanghai under four extreme storm and flood scenarios were studied.With the decreasing probability of the occurrence of extreme storm and flood scenarios,the exposed area and value of residential,commercial,office and industrial buildings in Shanghai continue to rise,reaching the maximum value under the extreme storm and flood scenario that occurs once in 5,000 years.Under the four extreme storm and flood scenarios,the exposed area and value of residential buildings are always the highest,while that of commercial buildings is always the lowest.From the perspective of spatial distribution,the exposed area and exposed value of four kinds of buildings in Shanghai ranged from sporadic distribution once in 200 years to contiguous distribution area centered on the central area of Shanghai and Songjiang Lowland once in 5000 years.From the perspective of the administrative region,the exposure value of the four types of buildings is the highest in Pudong district under the extreme storm and flood scenario,which happens once every 5,000 years.(3)The loss distribution of residential,commercial,office and industrial buildings in Shanghai under four extreme storm and flood scenarios was studied.With the decreasing probability of the occurrence of extreme storm and flood scenarios,the loss value of residential,commercial,office and industrial buildings in Shanghai continues to rise,reaching the maximum value under the extreme storm and flood scenario that occurs once in 5,000 years.In the four extreme storm and flood scenarios,the loss value of residential buildings is always the highest,and the exposed area and exposed value of commercial buildings are always the lowest.From the perspective of spatial distribution,the exposed area and exposed value of four kinds of buildings in Shanghai ranged from sporadic distribution once in 200 years to two lumpy areas centered on downtown Shanghai and Songjiang Lowland once in 5000 years.(4)Explored the areas that need to be paid attention to in the risk management of extreme storms and floods in Shanghai.The average annual loss of residential,commercial,office and industrial buildings in Shanghai was calculated.The average annual loss of residential,commercial,office and industrial in Shanghai was 35 million CNY,7 million CNY,14 million CNY and 14 million CNY respectively,totaling 70 million CNY.From the perspective of spatial distribution,the areas with high annual average losses of the four types of buildings in Shanghai are mainly concentrated in the downtown area,Wusongkou,the south of Jiading District and the north of Hangzhou Bay.