Hong et al. (2025) Quantifying Impacts of Precipitation and Evapotranspiration on Future Runoff in the Han River Basin Using the Budyko Framework

Identification

• Journal: KSCE Journal of Civil Engineering
• Year: 2025
• Date: 2025-11-01
• Authors: Da Hong, Jeongwoo Han, Hyun‐Han Kwon, Tae‐Woong Kim
• DOI: 10.1016/j.kscej.2025.100460

Research Groups

• Department of Civil and Environmental System Engineering, Hanyang University, Seoul, Korea.
• BK21 Four R&E Center for Civil, Environmental and Architectural Engineering, Korea University, Seoul, Korea.
• Department of Civil and Environmental Engineering, Sejong University, Seoul, Korea.
• Department of Civil and Environmental Engineering, Hanyang University (ERICA), Ansan, Korea.

Short Summary

This study quantifies the relative impacts of precipitation and potential evapotranspiration on future runoff in the Han River basin using the Budyko framework. The findings reveal that precipitation is the dominant driver of projected runoff increases, contributing between 67% and 84% to the total change.

Objective

• To quantify the individual contributions of precipitation (P) and potential evapotranspiration (PET) to changes in future runoff under different Shared Socioeconomic Pathway (SSP) climate change scenarios.

Study Configuration

• Spatial Scale: The Han River basin, South Korea (drainage area of 26,018 km²), analyzed across 30 middle-sized sub-basins.
• Temporal Scale: Baseline Period (BP: 1975–2020), Near Future (NF: 2021–2060), and Far Future (FF: 2061–2100).

Methodology and Data

• Models used: GR4J (Génie Rural à 4 paramètres Journalier) rainfall-runoff model; Climate Elasticity Method based on the Budyko framework (CEMBF); Spatial Proximity Model (for parameter transfer to ungauged basins).
• Data sources: 16 Global Climate Models (GCMs) from the Coupled Model Intercomparison Project Phase 6 (CMIP6) under SSP2-4.5 and SSP5-8.5 scenarios; historical meteorological data from 60 Korea Meteorological Administration (KMA) stations; dam inflow data from the Water Management Information System (WAMIS).
• PET Estimation: Calculated using the temperature-based Hargreaves method.

Main Results

• Runoff Projections: Annual runoff is projected to increase significantly compared to the baseline. Under SSP2-4.5, increases of 22.39% (NF) and 34.72% (FF) are expected; under SSP5-8.5, increases reach 27.46% (NF) and 48.45% (FF).
• Climate Shift: The aridity index (PET/P) is projected to decrease by 0.08–0.09, indicating a shift toward a more humid climate and energy-limited conditions.
• Contribution Analysis: Precipitation (P) is the primary driver of runoff changes, with a contribution ratio of 67%–84%. Potential evapotranspiration (PET) contributes 11%–24%.
• Elasticity: The mean precipitation elasticity coefficient ($\epsilonP$) was approximately 1.8, while the PET elasticity coefficient ($\epsilon{PET}$) was approximately -0.8, indicating runoff is more sensitive to changes in precipitation.

Contributions

• Extends the application of the Budyko framework from historical attribution studies to future climate projections.
• Isolates the specific roles of P and PET in driving future hydrological changes in a monsoonal, humid basin.
• Provides a scientific basis for water resource management and flood mitigation strategies in South Korea by quantifying the sensitivity of runoff to specific climatic drivers.

Funding

• Ministry of Interior and Safety (MOIS, Korea), Cooperative Research Method and Safety Management Technology in National Disaster project (Reference code: 2022-MOIS63-001).

Citation

@article{Hong2025Quantifying,
  author = {Hong, Da and Han, Jeongwoo and Kwon, Hyun‐Han and Kim, Tae‐Woong},
  title = {Quantifying Impacts of Precipitation and Evapotranspiration on Future Runoff in the Han River Basin Using the Budyko Framework},
  journal = {KSCE Journal of Civil Engineering},
  year = {2025},
  doi = {10.1016/j.kscej.2025.100460},
  url = {https://doi.org/10.1016/j.kscej.2025.100460}
}

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