Investigating climate change-induced extreme floods: Insights from super-high-resolution climate datasets using Rainfall-Runoff-Inundation (RRI) model

Study region Characterized by steep mountainous terrain, short river systems, and frequent typhoon-induced rainfall, the river basins of Taiwan are highly susceptible to flooding. Despite the expected intensification of extreme precipitation under climate change, regional hydrological assessments using super-high-resolution climate projections remain limited. Study focus This study investigates the impacts of future climate change on extreme streamflow and flood hazards across 15 hydrological stations representing major river basins in Taiwan. Super-high-resolution climate projections from the Meteorological Research Institute Atmospheric General Circulation Model (MRI-AGCM3.2S HighResMIP) and the Database for Policy Decision Making for Future Climate Change (d4PDF) under the 4°C warming experiment were coupled with a Rainfall-Runoff-Inundation (RRI) model to simulate flood responses. Annual peak discharges were estimated for near-future (2020–2040), mid-future (2050–2070), and far-future (2080–2100) periods under 10-, 100-, and 1000-year return periods. New hydrological insights for the region The simulations indicate that projected annual peak discharges under the 4°C warming scenario consistently exceed those under the present climate across all return periods, indicating an increased probability of extreme flood events throughout Taiwan. The magnitude of change varies among river basins, demonstrating strong regional heterogeneity in hydrological responses to climate change. These findings provide new evidence that super-high-resolution climate projections improve the representation of future flood extremes and offer valuable regional-scale information for flood risk assessment, climate adaptation planning, and the design of resilient water resources and flood management strategies in Taiwan.