Strengthened tropical cyclones and higher flood risk under compound effect of climate change and urbanization across China's Greater Bay Area

Abstract

Climate change and urbanization will further exacerbate tropical cyclones (TCs) causing severer flooding especially in coastal urbanized areas. In this study, the compound effects of climate change and urbanization on organized TC and its flood risk across the Guangdong-Hong Kong-Macau Greater Bay Area (GBA) were explored and future projections of 10 models in different Shared Socioeconomic Pathways (SSPs) and Representative Concentration Pathways (RCPs) in Coupled Model Intercomparison Project 6 (CMIP6). The typical TC named Ewiniar that caused tremendous rainfall and flooding over GBA is taken as a case. We found that future TC will be exacerbated with rainfall band shifting inland and covering larger areas compared to the current scenario due to climate change and urbanization, and rainfall amount in the central rainfall band increases by 24% and 28% under SSP2-RCP4.5 and SSP5-RCP8.5, respectively. Due to the land-atmosphere interactions, future actual direct runoff increased by 7.91%–15.53% during the TC Ewiniar under SSP2-RCP4.5 and SSP5-RCP8.5, leading to further expansion of the area marked with the highest flood risk (24% and 39%, respectively). Our study highlights the adverse compound effect of climate change and urbanization on TC and flood risk, helping to develop TC-related disaster prevention and mitigation policies.