Evaluation of the impact of extreme storm surge and rainfall in coastal areas

Under global warming, extreme meteorological events may increase in some regions in terms of both frequency and intensity in the future. Low-lying coastal areas may face the threat both from intensive rainfall and high sea level caused by sea level rise and enhanced storm surge. The Pearl River Delta (PRD) is one of the economic centers of China and is very densely populated. However, PRD is one of the most storm surge-exposed and flood-exposed urban areas in the world. This paper aims to assess the possible impacts of extreme sea level and rainfall on the costal urban areas in PRD. Frequency analysis on historical data of storm surge level and rainfall intensity is conducted, and several scenarios of combination of different magnitudes of the two meteorological events are designed. The trend of observed local sea level and possible land subsidence are also considered. The scenarios are used as inputs for a flood routing model to evaluate the combined impacts of the two meteorological events. Flood maps are produced for each scenario and the infrastructures potentially affected such as buildings and roads can be identified. The results can help identify critical areas prone to hazards under extreme cases and are meaningful for designing hazard prevention measurements.