Future Urban Expansion Simulation and Flood Mitigation Assessment in the Pearl River Delta under Flood Risk Avoidance

Combined with flood risk avoidance-oriented urban expansion strategies, future urban expansion spatial patterns were simulated under Shared Socioeconomic Pathways (SSPs) and Representative Concentration Pathways (RCPs) scenarios. This study compared urban expansion and expected annual damage to evaluate the flood mitigation effects of different strategies. The results show many newly expanded urban lands in the Pearl River Delta are located in floodplains, and the expected annual damage caused by floods is enormous. The most serious economic losses caused by floods were concentrated in southern Guangzhou, eastern Foshan, northern Zhongshan, and northwestern Dongguan. Under the SSP5-RCP8.5-natural expansion scenario, the newly expanded urban lands in floodplains of the Pearl River Delta in 2080 will be 1,633 square kilometers (equivalent to the built-up areas of Guangzhou, Foshan, and Zhongshan combined in 2021), accounting for 31.5% of the total newly expanded urban lands; the expected annual damage will be 2