Robelin et al. (2025) RECHARGE, a model of potential recharge of aquifers applied to mainland France

Identification

• Journal: Journal of Hydrology
• Year: 2025
• Date: 2025-11-20
• Authors: Olivier Robelin, Sandra Lanini, Yvan Caballero, Éric Sauquet
• DOI: 10.1016/j.jhydrol.2025.134631

Research Groups

• INRAE - RiverLy, Centre Lyon-Grenoble Auvergne-Rhône-Alpes, France.
• BRGM (French Geological Survey), Montpellier, France.
• UMR 183 G-Eau, (University of Montpellier, AgroParisTech, BRGM, CIRAD, INRAE, Institut Agro, IRD), Montpellier, France.

Short Summary

The study introduces the RECHARGE model, a simplified soil water balance approach designed to estimate potential groundwater recharge across mainland France by correlating effective precipitation with a cartographic infiltration index (IDPR). The model provides a robust, large-scale estimation of renewable groundwater resources, validated against observed river flows and the physically-based SURFEX model.

Objective

• To develop a method for calculating potential groundwater recharge from precipitation infiltration that accounts for climate and land cover variability without requiring detailed local aquifer hydrodynamic properties.

Study Configuration

• Spatial Scale: Mainland France, utilizing an 8 km x 8 km meteorological grid (SAFRAN), a 50 m resolution infiltration index (IDPR), and aggregated results for 621 national groundwater bodies (MESO).
• Temporal Scale: Historical period from 1959 to 2020, utilizing daily time steps aggregated to monthly and annual scales.

Methodology and Data

• Models used:
  • RECHARGE: An ensemble model averaging three soil water balance formulations (Thornthwaite, Dingman, and Edijatno & Michel).
  • SURFEX v8.0: A physically-based land surface model used as a reference for validation.
• Data sources:
  • Meteorological: SAFRAN near-surface reanalysis (Precipitation, Temperature, ET0).
  • Land Cover: Corine Land Cover (CLC) 2018 to derive seasonal crop coefficients ($K_c$).
  • Hydrogeological: BDLisa v3 database for lithology and aquifer units.
  • Infiltration Index: IDPR (Network Development and Persistence Index) at 50 m resolution.
  • Observations: Daily river discharge from 611 reference gauging stations.
• Key Parameterization: Calculation of the Effective Precipitation Infiltration Ratio (EPIR) based on linear regressions between the Baseflow Index (BFI) and IDPR across different lithological classes (sedimentary, karst, hard rock, etc.).

Main Results

• Average Recharge: The mean annual potential groundwater recharge for mainland France (1991–2020) was estimated at 250 mm/year.
• Model Performance: RECHARGE effective precipitation ($P{eff}$) showed high correlation ($R^2 > 0.70$) with SURFEX outputs and consistent temporal dynamics with observed river flows ($QA$).
• BFI Stability: Analysis of 556 catchments confirmed that the Baseflow Index is highly stable over time (median variation of 0.67% per decade), justifying the use of a constant EPIR.
• Lithological Relationships: Significant correlations were found between BFI and IDPR for sedimentary ($R^2 = 0.46$) and karst ($R^2 = 0.39$) formations, while a constant EPIR of 0.6 was assigned to hard rock areas.
• Seasonal Accuracy: The model effectively captures winter recharge (the primary recharge period), though it shows some discrepancies in mountainous regions due to simplified snowmelt processing.

Contributions

• Methodological Innovation: Original use of the IDPR cartographic index to spatialise the infiltration ratio (EPIR) across a national territory.
• Scalability: Provides a tool for water managers to assess groundwater renewal and climate change impacts at regional or national scales without complex numerical groundwater modeling.
• Data Integration: Successfully combines qualitative GIS-derived indices with quantitative hydrological signatures (BFI) to bridge the gap between surface hydrology and hydrogeology.

Funding

• Explore2 Project: Funded by the French Ministry of the Environment and the French Biodiversity Agency (OFB).
• Computational Support: Centre de Calcul Scientifique en région Centre-Val de Loire.

Citation

@article{Robelin2025RECHARGE,
  author = {Robelin, Olivier and Lanini, Sandra and Caballero, Yvan and Sauquet, Éric},
  title = {RECHARGE, a model of potential recharge of aquifers applied to mainland France},
  journal = {Journal of Hydrology},
  year = {2025},
  doi = {10.1016/j.jhydrol.2025.134631},
  url = {https://doi.org/10.1016/j.jhydrol.2025.134631}
}

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