Beguería et al. (2025) Water balance components of the Pyrenees: a 30-year modeling study in a transboundary context

Identification

• Journal: DIGITAL.CSIC (Spanish National Research Council (CSIC))
• Year: 2025
• Date: 2025-12-01
• Authors: Beguería, Santiago, Palazón Tabuenca, Leticia, Quintana-Seguí, Pere, Clavera-Gispert, Roger, Barella-Ortiz, Anaïs, Cakir, Roxelane, Grusson, Youen, Sauvage, Sabine, Sánchez-Pérez, José Miguel
• DOI: 10.20350/digitalcsic/17762

Research Groups

• Consejo Superior de Investigaciones Científicas (CSIC), including Estación Experimental de Aula Dei (EEAD)
• Other collaborating institutions involved in the transboundary study (authors are from various institutions, though not explicitly listed in the provided text, the collaborative nature is clear).

Short Summary

This study reconstructed the Pyrenean water balance for 1981–2010 using two hydrological models, revealing strong hydroclimatic gradients, declining groundwater recharge, and a shift towards water-limited conditions, thereby establishing the first integrated transboundary hydrological baseline for the region.

Objective

• To reconstruct the regional water balance components of the Pyrenees for the period 1981–2010 using two contrasting hydrological models (SASER and SWAT) to understand the heterogeneous hydrological regimes and establish a transboundary hydrological baseline for cooperative water management.

Study Configuration

• Spatial Scale: The entire Pyrenees mountain range, covering a transboundary region across Spain, France, and Andorra.
• Temporal Scale: A 30-year period, from 1981 to 2010.

Methodology and Data

• Models used:
  • SASER: A fully distributed physically based hydrological model.
  • SWAT: A semi-distributed conceptual hydrological model.
• Data sources:
  • Shared high-resolution meteorological dataset (for forcing both models).
  • MODIS-based evapotranspiration products (for model evaluation).
  • MODIS-based snow products (for model evaluation).
  • Discharge data (implied for model calibration/evaluation).

Main Results

• Strong hydroclimatic gradients were observed across the Pyrenees.
• Precipitation exceeds 2000 mm/year in Atlantic headwaters but declines below 1000 mm/year in southern and eastern foothills.
• Snowfall and snowmelt dominate high central and western ranges, sustaining summer flows.
• Evapotranspiration (400–800 mm/year) is the largest water loss flux and exhibits a clear northwest–southeast gradient.
• Rising potential evapotranspiration and declining actual evapotranspiration to potential evapotranspiration ratios indicate a shift toward water-limited conditions.
• Groundwater recharge is modest (<150 mm/year) and shows a declining trend, suggesting reduced baseflow resilience.
• Water yield peaks near 1500 mm/year in the humid northwest but falls below 200 mm/year in the arid southeast, with a slight downward trend.
• The relative contribution of snow to runoff has increased, primarily due to declining rainfall-driven runoff rather than enhanced snowmelt.
• Broad-scale hydrological controls are robust across both models, but discrepancies with MODIS data highlight structural and observational uncertainties.

Contributions

• Establishes the first integrated, transboundary hydrological baseline for the Pyrenees, providing a crucial foundation for cooperative water management under global change.
• Provides a comprehensive reconstruction of the regional water balance components over a 30-year period using two distinct hydrological models.
• Evaluates model outputs against independent satellite-based evapotranspiration and snow products, enhancing the assessment beyond traditional discharge calibration.
• Quantifies spatial and temporal gradients of key water balance components (precipitation, evapotranspiration, snowmelt, groundwater recharge, water yield) across the entire Pyrenean region.

Funding

• Interreg POCTEFA

Citation

@article{Beguería2025Water,
  author = {Beguería, Santiago and Palazón Tabuenca, Leticia and Quintana-Seguí, Pere and Clavera-Gispert, Roger and Barella-Ortiz, Anaïs and Cakir, Roxelane and Grusson, Youen and Sauvage, Sabine and Sánchez-Pérez, José Miguel},
  title = {Water balance components of the Pyrenees: a 30-year modeling study in a transboundary context},
  journal = {DIGITAL.CSIC (Spanish National Research Council (CSIC))},
  year = {2025},
  doi = {10.20350/digitalcsic/17762},
  url = {https://doi.org/10.20350/digitalcsic/17762}
}

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