Quantifying impacts of precipitation and evapotranspiration on future runoff in the Han River basin using the Budyko framework

Changes in hydrometeorological variables due to climate change are expected to affect changes in runoff, posing challenges for water resource management and increasing the risk of economic and environmental hazards. This study simulated future runoff for the Han River basin using the GR4J under different climate change scenarios. The climate elasticity approach, based on the Budyko framework, quantified the contributions of precipitation (P) and potential evapotranspiration (PET) to changes in runoff. Runoff was projected to increase for the near future (NF, 2021–2060) and far future (FF, 2061–2100) compared to the baseline period (BP, 1975–2020). Runoff increased by 22.39 % for NF and 34.72 % for FF under the SSP2–4.5 scenario and by 27.46 % for NF and 48.45 % for FF under the SSP5–8.5 scenario. The aridity index (PET/P) decreased by 0.08–0.09, indicating a shift toward a more humid climate. Because PET and P contributed to changes in runoff by 11 %–24 % and 67 %–84 %, respectively, P was identified as the main cause of the change therein. The findings of this study can be beneficial for water resource management and establishing climate change adaptation measures for the Han River basin.