Clemenzi et al. (2025) Attributing European runoff changes to climatic drivers under future conditions

Identification

• Journal: Journal of Hydrology
• Year: 2025
• Date: 2025-12-16
• Authors: Ilaria Clemenzi, Yiheng Du, Ilias Pechlivanidis
• DOI: 10.1016/j.jhydrol.2025.134794

Research Groups

• Swedish Meteorological and Hydrological Institute (SMHI), Norrköping, Sweden.

Short Summary

This study attributes future European runoff changes to precipitation and potential evapotranspiration using a Budyko-based framework across 35,408 basins. It finds that while precipitation is the dominant driver under most scenarios, potential evapotranspiration becomes equally significant in central and southern Europe under high-emission scenarios by the late century.

Objective

• To quantify the sensitivity of runoff to climatic drivers and attribute future runoff changes to precipitation ($P$) and potential evapotranspiration ($E_0$) across diverse European hydrological regimes.
• To investigate how the relative contribution of these drivers varies across different future periods (early, mid, and late century) and emission scenarios (RCP 2.6, 4.5, and 8.5).

Study Configuration

• Spatial Scale: Pan-European domain covering 35,408 sub-basins (average area ~215 km² per sub-basin).
• Temporal Scale: Reference period (1971–2000) and three future periods: early century (2011–2040), mid-century (2041–2070), and late century (2071–2100).

Methodology and Data

• Models used: E-HYPE (European configuration of the Hydrological Predictions for the Environment model), a semi-distributed, process-based model.
• Framework: Budyko-based elasticity framework (Yang’s equation) used to calculate elasticity coefficients ($\epsilonP$ and $\epsilon{E0}$) and attribute runoff changes ($\Delta Q$) to climatic drivers.
• Data sources: Nine bias-adjusted regional climate simulations from Euro-CORDEX, including three Representative Concentration Pathways (RCP 2.6, 4.5, and 8.5).
• Classification: 11 hydrological clusters defined by 15 streamflow signatures (e.g., baseflow index, flashiness, snowmelt impact) to link attribution to local hydrological behavior.

Main Results

• Runoff Sensitivity: Median elasticity of runoff to precipitation ($\epsilonP$) ranges from 0.5 to 3.6, while elasticity to potential evapotranspiration ($\epsilon{E0}$) ranges from 0.1 to 2.4. Northern and central Europe show higher sensitivity to $P$ than to $E_0$.
• Driver Attribution: Precipitation is the primary driver of runoff changes under low and medium emission scenarios. However, under RCP 8.5 by the late century, the contribution of $E_0$ becomes comparable to $P$ in central and southern Europe.
• Regional Trends: Runoff is projected to increase in Scandinavia and northeastern Europe (driven by increased $P$) and decrease in southern Europe (driven by decreased $P$ and increased $E_0$).
• Regime Influence: Basins highly responsive to precipitation (Clusters 2 and 6) remain primarily driven by $P$ changes. In contrast, basins with slow responses or low runoff coefficients (Clusters 1, 4, and 10) show a more balanced contribution from both $P$ and $E_0$ under high-warming scenarios.

Contributions

• Provides a novel pan-European attribution analysis that links long-term runoff changes to specific climatic drivers using the Budyko framework.
• Establishes a clear link between catchment hydrological signatures (regimes) and their sensitivity to future climatic shifts.
• Offers a diagnostic approach to support targeted local and transboundary water management and adaptation strategies by identifying where $E_0$ may override $P$ as a dominant driver.

Funding

• EU Horizon 2020 project CLINT (Climate Intelligence: Extreme events detection, attribution and adaptation design using machine learning; grant no. 101003876).
• EU Horizon 2020 project I-CISK (Innovating climate services through integrating scientific and local knowledge; grant no. 101037293).

Citation

@article{Clemenzi2025Attributing,
  author = {Clemenzi, Ilaria and Du, Yiheng and Pechlivanidis, Ilias},
  title = {Attributing European runoff changes to climatic drivers under future conditions},
  journal = {Journal of Hydrology},
  year = {2025},
  doi = {10.1016/j.jhydrol.2025.134794},
  url = {https://doi.org/10.1016/j.jhydrol.2025.134794}
}

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