Future projection of compound flooding using downscaled CMIP6 GCM climate projections in the Mekong River Basin

We analysed flood dynamics, compound flooding, and the intersection of climate change and dam development in the Mekong River Basin (MRB), focusing specifically on flooding in the Lower Mekong Basin (LMB). The study revealed a substantial increase in flood magnitude and frequency in the MRB due to climate change. During the peak discharge season in September, key hydrological stations are projected to experience average discharge increases of 10.86% Shared Socioeconomic Pathway 2–4.5 (SSP245) and 13.80% Shared Socioeconomic Pathway 5–8.5 (SSP585) in the near future (2021–2060), rising further to 25.78% (SSP245) and 59.43% (SSP585) in the far future (2061–2100). Emphasis is placed on compound flooding, with a 100-year return level indicating a projected increase of 16% and 18% in inundation extent and 27% and 30% in inundation water volume for SSP245 and SSP585, respectively. The study highlights the impact of MRB dam construction on flood risk, offering insights for effective flood management and preparedness amidst climate change threats.