The contributions of hazard and exposure to flood risk in Shenzhen city

Abstract

Flood risk strongly depends on the hazard and the exposure of people and assets. With the continuous growth of the urban population, exposure is contributing more and more to urban flood risk. Meanwhile, climate warming has led to frequent extreme precipitation events, resulting in severe flood hazards in cities. However, the individual contributions of hazard and exposure to flood risk remain unclear, hindering effective risk reduction strategies in metropolitan areas. This study examines the contributions of pluvial flood hazard and population exposure to the population mortality risk, as well as the contributions of pluvial flood hazard and urban built-up area exposure to the economic loss risk in the Shenzhen metropolitan area. The results indicate that the concentration of population and assets in central Shenzhen increases the pluvial flood risk. With almost the same water depth, Longgang, Longhua, and Luohu districts exhibit higher death tolls and asset losses compared to the Guangming district. Additionally, changes in pluvial flood hazard also significantly contribute to the variation in economic loss risk, which could explain up to 84 % of the observed fluctuations. With the existing distribution of population and urban built-up areas, pluvial flood risk in Shenzhen is expected to increase in the future as extreme precipitation intensifies.