Climate change impact assessment on water resources management using a combined multi-model approach in South Korea

Study Region: Hapcheon and Seomjingang Basins, South Korea Study Focus: This study investigated the impacts of climate change on water supply reliability and flood risk in two East Asian basins in South Korea. By employing three coupled hydrological and reservoir operation models, the analysis considered projections under SSP2-4.5 and SSP5-8.5, projected using 12 global climate models. New Hydrological Insights: Our results indicated that under SSP2-4.5, water supply reliability did not considerably decrease compared to the historical period (1995–2014), whereas it was reduced under SSP5-8.5 in one basin, Hapcheon. Meanwhile, a substantial increase in flood risk was modeled in both basins under both scenarios. The impact of climate change was amplified through a cascade from rainfall to runoff and then to flood volume, resulting in heightened flooding risk. In the far future (2081-2100) under SSP5-8.5, the dam-released flood volume was projected to increase rapidly by 73.2% and 74.1% in the Hapcheon and Seomjingang Basins, respectively, indicating considerable changes in flood risk due to climate change. Compared with SSP2-4.5, SSP5-8.5 exhibited more variability among climate models, especially in the far future period (2081–2100), leading to more uncertain projections in drought and flood risk assessments.