Risk assessment of shanghai extreme flooding under the land use change scenario

Environmental changes have led to non-stationary flood risks in coastal cities. How to quantitatively characterize the future change trend and effectively adapt is a critical problem that needs urgent attention. To this end, this study uses the 2010 Shanghai land use data as the base and utilizes the future land use simulation (FLUS) model to simulate future land use change scenarios (2030, 2050, and 2100). Based on the results of storm and flood numerical simulations, probabilistic risk, and other multidisciplinary methods, extreme storm and flood risks of various land uses (residential, commercial and public service, industrial, transportation, agricultural, and other land) in Shanghai are analyzed. Our findings demonstrate that the future land use simulated results show that the simulation accuracy is very high, meeting the needs of our research. We evaluated future land use exposure assets and losses and found that their spatial distribution patterns are consistent, ranging from a sporadic distribution for 1/10-year to a banded distribution for 1/1000-year under the two emission scenarios. In terms of economic loss, the losses of total land use in Shanghai for 1/1000-year in 2100 are 1.8-2.7 times that of 2010 under the RCP8.5 scenario. The expected annual damage (EAD) of Shanghai's land use in 2030, 2050, and 2100 is 189.9 million CNY, 409.8 million CNY, and 743.5 million CNY under the RCP8.5 scenario, respectively, which is 1.7-3.0 times the EAD under the RCP2.6 scenario. Among them, residential, commercial and public service land as well as industrial land has the highest EAD. Risks are mainly distributed in the city center, the lower reaches of the Huangpu River, the northern shore of Hangzhou Bay, the Qingpu (QP)-Songjiang (SJ) depression in the southwest, and Chongming (CM) Island (southwest and northeast). Our work can provide meaningful information for risk-sensitive urban planning and resilience building in Shanghai. These multidisciplinary methods can also be applied to assess flood risk in other coastal cities.