Zabaleta et al. (2025) Changing rivers: Hydrological shifts in the Pyrenees revealed by daily streamflow indicators (1950–2019)

Identification

• Journal: DIGITAL.CSIC (Spanish National Research Council (CSIC))
• Year: 2025
• Date: 2025-12-01
• Authors: Zabaleta, Ane, Palazón Tabuenca, Leticia, Antigüedad, Iñaki, Beguería, Santiago
• DOI: 10.20350/digitalcsic/17765

Research Groups

Estación Experimental de Aula Dei (EEAD), CSIC (Consejo Superior de Investigaciones Científicas)

Short Summary

This study provides the first region-wide assessment of daily streamflow trends across the Pyrenees from 1950 to 2019, revealing a robust long-term decline in mean, low, and high flows, alongside an emerging shift towards rain-dominated winter regimes.

Objective

• To provide the first region-wide assessment of streamflow trends across the Pyrenees based on daily flow records and derived hydrological indicators, analyzing long-term changes in mean, low-, and high-flow indices at both annual and monthly scales.

Study Configuration

• Spatial Scale: The Pyrenees mountain range, encompassing areas in Spain, France, and Andorra.
• Temporal Scale: 1950–2019.

Methodology and Data

• Models used: Hydrological indicators derived from daily streamflow data (e.g., mean, low-flow, and high-flow indices). No specific process-based hydrological models were explicitly mentioned.
• Data sources: Daily streamflow data from 93 gauging stations located in Spain, France, and Andorra.

Main Results

• A robust long-term decline in Pyrenean river flows was observed across the region.
• Since 1960, median daily discharge decreased by 4–13% per decade.
• Low flows decreased by 5–14% per decade.
• High flows decreased by 3–11% per decade.
• Declines were strongest in spring, summer, and autumn (particularly October), including significant reductions in baseflows.
• High-flow indicators showed emerging increases in winter (January–February) since the 1990s, reflecting a transition from snow- to rain-dominated regimes.
• The dominant signal of decline was homogeneous across the mountain range, with secondary north–south and east–west contrasts emerging seasonally.

Contributions

• Provides the first region-wide assessment of streamflow trends across the Pyrenees using daily flow records, moving beyond traditional analyses based on monthly or annual discharge.
• Reveals the magnitude and temporal reorganization of hydrological regimes by capturing changes in the full distribution of daily streamflow.
• Highlights critical implications for water resource management, including reduced summer water availability, increased drought risk, and potential intensification of winter floods, underscoring the need for adaptive strategies.

Funding

• Interreg POCTEFA

Citation

@article{Zabaleta2025Changing,
  author = {Zabaleta, Ane and Palazón Tabuenca, Leticia and Antigüedad, Iñaki and Beguería, Santiago},
  title = {Changing rivers: Hydrological shifts in the Pyrenees revealed by daily streamflow indicators (1950–2019)},
  journal = {DIGITAL.CSIC (Spanish National Research Council (CSIC))},
  year = {2025},
  doi = {10.20350/digitalcsic/17765},
  url = {https://doi.org/10.20350/digitalcsic/17765}
}

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