Impact of tropical cyclones and socioeconomic exposure on flood risk distribution in the Mekong Basin

Tropical cyclones have a big impact on flood risk, and understanding how their activity interacts with population exposure under climate change is critical. Here we investigate spatiotemporal changes in flood risk using numerical models together with historical observations and future projections of tropical cyclone tracks. We find that tropical cyclone-related flood risk shifts from the Mekong Delta to the eastern lower Mekong Basin, driven by the interaction between tropical cyclones and population exposure. Historically, extreme precipitation from tropical cyclones increased flood risk in about 14% and decreased in 7% of the basin. Future tropical cyclones may increase flood risk in about 7% and reduce in nearly 18% of the basin. Moreover, population exposure growth has historically increased flood risk in 3% of the basin and is projected to result in a 1% increase. These findings highlight the complex interactions of tropical cyclone hazards and socioeconomic factors influencing flood risk. The geographical distribution of flood risk in the Mekong Basin has changed as a result of shifts in extreme precipitation from tropical cyclones as well as population exposure and is projected to continue to evolve, according to simulations with a hydrological-hydrodynamic model and observations.