Riverine flood risk assessment with a combined model chain in southeastern China

Abstract

Climate change and rapid urbanization have exacerbated the occurrence and impact of floods. It is essential to carry out a quantitative flood risk assessment and manage the flood risk before a disaster occurs. This article presents a combined riverine flood risk model to obtain the exceedance probability loss (EPL) curve and expected annual damage (EAD) under the current climate. This model includes a rapid flood model and a flood damage model. It aims to simulate the flood risk and evaluate the flood damage at 10-, 30-, 50-, 100-, and 200-year return period events. The results show that: (1) The total inundation areas will sharply increase when the flood return periods are over 30 years. (2) The EAD is 1,476 million dollars in the Jiulong River Basin (JRB). When the flood return period is over 30 years, the total damage increases sharply. (3) The flood risk in the lower reaches of the JRB is higher than in the upper reaches when the flood event is beyond a 20-year return period. (4) Industrial sector damage is the largest, followed by tertiary industry, transportation, construction, agriculture, and infrastructure. The combined model chain can quickly assess the flood risk in the river basin and judge the flood risk in a watershed compared to the national level. In addition, it can be applied to other river basins, and it will provide actionable information for future flood risk management.