Abstract
Extreme flooding usually causes huge losses of residential buildings and household properties, which is critical to flood risk analysis and flood resilience building in Shanghai. We developed a scenario-based multidisciplinary approach to analyze the exposure, losses and risks of residential buildings and household properties, and their spatial patterns at the neighborhood committee level in Shanghai, based on extreme storm flood scenarios of 1/200, 1/500, 1/1000 and 1/5000-year. Our findings show that the inundation area of the residential buildings caused by a 1/200-year storm flood reaches 24.9 km2, and the total loss of residential buildings and household properties is 29.7 billion CNY (Chinese Yuan) (or 4.4 billion USD), while the inundation area of residential buildings and the total loss increases up to 162.4 km2 and 366.0 billion CNY (or 54.2 billion USD), respectively for a 1/5000-year storm flood. The estimated average annual loss (AAL) of residential buildings and household properties for Shanghai is 590 million CNY/year (or 87.4 million USD/year), with several hot spots distributed around the main urban area and on the bank of the Hangzhou Bay. Among sixteen districts, Pudong has the highest exposure and annual expected loss, while the inner city is also subject to extreme flooding with an AAL up to near half of the total. An analysis of flood risk in each of 209 subdistricts/towns finds that those most vulnerable to storm flooding are concentrated in Pudong, Jiading, Baoshan Districts and the inner city. Our work can provide meaningful information for risk-sensitive urban planning and resilience building in Shanghai. The methodology can also be used for risk analysis in other coastal cities facing the threat of storm flooding.
Highlights
Floods affecting Shanghai are usually categorized into fluvial, pluvial and coastal storm flooding
The exposure of household properties is an order of magnitude smaller than that of residential buildings, but the loss of household properties accounts for about 27% of the total losses, indicating that household properties are much more vulnerable to flooding
(2) The inundated residential building area caused by 1/200-year and 1/5000-year events increases from 24.9 km2 to 162.4 km2, and the total loss of residential buildings and household properties escalate from 29.7 billion CNY (4.4 billion USD) to 366.0 billion CNY (54.4 billion USD), with widespread impact throughout Shanghai city
Summary
Floods affecting Shanghai are usually categorized into fluvial, pluvial and coastal storm flooding. Located at the mouth of the Yangtze River, Shanghai is one of the most exposed coastal megacities to extreme flooding, caused by a typhoon induced storm surge in combination with a high astronomic tide, heavy rain, and a fluvial flood [1,2,3,4,5,6,7,8]. Climate change, sea level rise, land subsidence and rapid urban growth will significantly increase the risk of extreme flooding for Shanghai in the future [1,2,4,5,9,10,11,12]. The extreme flood risk with low-probability and high consequence has been focused in recent decades because it can cause catastrophic damage and losses for the city’s social, economic sectors, infrastructure and environment as well [1,4,11,21,22,23,24,25]
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