Estimating Compound Fluvial & Coastal Flood Risk in SEA

This project contributes to Southeast Asia's most pressing needs related to coastal defense against climate change. Findings from this project will not only help Singapore to better understand and prepare for increasing coastal flooding risk but also help surrounding countries for better coastal adaptation, which will have large international impacts. Scientific outcomes from this project should place NUS at the forefront of research institutes in the world to manage coastal flood risks. This project is the first to develop a long-term, consistent, and comprehensive catalog of extreme water levels (EWLs) over the entire Asia Pacific. This catalog consists of an unprecedented level of detailed information of EWL events, regarding their regional spatial-temporal characteristics and risk maps with different return periods. This catalog will form the basis for an analysis of the changing risk of compound inland-coastal floods that will underscore national and international climate change assessments.

Moreover, it could provide crucial insights to guide resilient and cost-effective coastal line adaptation strategies, including both engineering-based and nature-based solutions.

The engagement of students in cutting-edge research enhances their academic and professional skills, while the dissemination of findings through publications and conferences positions NUS as a leading institution in climate risk research.

A total of 245,000 significant inland and coastal flood events were identified, 12,500 of which were compound floods, resulting in an occurrence rate of 10% (since each event includes both inland and coastal components). We also identified 938 unique tropical cyclones whose tracks passed within a 200 km radius of inland locations. Notably, 1,621 of the 5,669 inland locations did not record any tropical cyclone influence during this period. These “zero-event” sites provide important negative controls that are essential for establishing a baseline flood frequency and for comparing the impacts across regions with differing cyclone exposure. Such an approach helps ensure that the flood hazard assessment is comprehensive and not biased toward areas with more frequent cyclone activity.

This research achieves an overview of compound flood and tropical cyclone trends in East Asia.