González-Ramón et al. (2025) Integration of 3d geological models and groundwater flow models for the improvement of the management of complex multilayer aquifers under intensive exploitation. The case of the Loma de Úbeda (Southern Spain)

Identification

• Journal: Journal of Hydrology Regional Studies
• Year: 2025
• Date: 2025-11-21
• Authors: Antonio González-Ramón, Javier Heredia, Carlos Marín-Lechado, Víctor J. Cifuentes
• DOI: 10.1016/j.ejrh.2025.102964

Research Groups

• Geological and Mining Institute of Spain, Spanish National Research Council (Granada and Madrid, Spain)
• Oficina de Planificación Hidrológica, Confederación Hidrográfica del Guadalquivir (Sevilla, Spain)

Short Summary

This study integrates 3D geological and numerical groundwater flow models to improve the management of the complex, intensively exploited multilayer aquifer system of Loma de Úbeda, Southern Spain. The research successfully corroborates the conceptual hydrogeological model and provides a validated tool for sustainable water resource management, highlighting the shift in water storage and flow dynamics due to prolonged pumping.

Objective

• To integrate a detailed 3D geological model with a numerical groundwater flow model to validate the conceptual hydrogeological functioning of the Loma de Úbeda Deep Multilayer Aquifer System (SAMPU) and provide an effective management tool for sustainable exploitation under intensive pumping and climate change scenarios.

Study Configuration

• Spatial Scale: The study area, Loma de Úbeda, covers approximately 1100 square kilometers (1.1 x 10^9 square meters). The numerical flow model domain covers 845.06 square kilometers (8.45 x 10^8 square meters) for Jurassic carbonates, 894.38 square kilometers (8.94 x 10^8 square meters) for Triassic lutites, and 987.75 square kilometers (9.88 x 10^8 square meters) for Triassic sandstones.
• Temporal Scale: Piezometric data were collected from August 1993 to November 2021. Hydrochemical data from 1991 to 2010. Isotopic data from 2012 to 2015. The numerical groundwater flow model simulates the period from October 2000 to October 2021 on a monthly basis.

Methodology and Data

• Models used:
  • GeoModeller (Intrepid Geophysics): For 3D geological modeling, using implicit interpolation, potential field theory, and universal cokriging.
  • MODFLOW-2005 (Harbaugh, 2005) in Visual MODFLOW 2009.1 Pro: For numerical groundwater flow modeling, utilizing finite difference code, RIVER, DRAIN, and WALL subroutines.
  • EASYBAL: For soil water balance calculations to estimate precipitation recharge.
  • PEST and UCODE: For model calibration and sensitivity analysis using the Gauss-Levenberg-Marquardt (GLM) iterative optimization algorithm.
• Data sources:
  • Geological: Surface geological observations, 1:50,000 geological maps, data from 195 deep wells (450-800 m), dip and fault orientations, kinematic indicators, reinterpreted 22 seismic reflection lines (413 km total).
  • Hydrogeological: Piezometric data from 161 wells (1800 measurements, 1208 for calibration in 25 wells), hydrochemical data from 566 samples, isotopic data (18O and Deuterium) from 238 monthly samples in 11 wells.
  • Climatic: Monthly precipitation data from 9 meteorological stations.
  • Exploitation: Inventory of irrigated areas (2008) and estimated groundwater abstraction volumes from 251 pumping wells (121 represented in the model).
  • River/Springs: Prescribed levels for the Guadalimar River and measured average flow rates for springs.

Main Results

• 3D Geological Model: Developed a robust 3D geological model of Miocene, Jurassic, and Triassic units, revealing a tabular morphology dipping approximately 2 degrees south, with thicknesses increasing southward. Numerous high-angle faults (average 10 km length, up to 70 m displacement) deform the units, creating complex compartmentalization and interconnection.
• Conceptual Hydrogeological Model Validation: The model successfully corroborates the complex conceptual model, demonstrating the interdependence of superimposed aquifers (Jurassic carbonates, Triassic lutites, Triassic sandstones) and their interaction with the Guadalimar River. Hydrochemical and isotopic data confirmed water mixing and flow exchanges between aquifers.
• Numerical Flow Model Performance: The transient regime model achieved an "Excellent" fit with a Nash-Sutcliffe Efficiency (E) of 0.828 and a Pearson correlation coefficient (R) of 0.913, with calibrated hydraulic parameters falling within plausible ranges.
• Impact of Intensive Pumping: Over the 21-year simulation period (2000-2021), dry areas within the aquifer system significantly expanded, and maximum piezometric levels showed an overall downward trend, while minimum levels decreased monotonically.
• Shift in Flow Dynamics and Water Balance:
  • Recharge from Tertiary detrital aquifers decreased from 10.5 x 10^6 cubic meters per year to 2 x 10^6 cubic meters per year.
  • Precipitation infiltration showed a decreasing trend, with a 57% reduction by the end of the period, and recharge shifting from dry Jurassic carbonates to underlying Triassic lutites.
  • Effective pumping decreased due to cell drying, with only 68.4% of the nominal volume pumped by the end of the period. Pumping shifted relatively from Jurassic to Triassic sandstones.
  • Natural discharge to the Guadalimar River reduced by nearly 75% (from 38 x 10^6 cubic meters per year to 9.4 x 10^6 cubic meters per year), while induced recharge from the river increased sharply from 0.25 x 10^6 cubic meters per year to 2 x 10^6 cubic meters per year.
• Sensitivity Analysis: Specific storage (Ss) of confined Jurassic carbonates, Triassic lutites, and Triassic sandstones, and the vertical hydraulic conductivity (Kz) of Triassic lutites, were identified as the most impactful parameters, reflecting the dominance of vertical flow circulation due to intensive pumping.

Contributions

• This study provides a robust methodology for integrating 3D geological models with numerical groundwater flow models, particularly valuable for complex, deep, and intensively exploited multilayer aquifer systems.
• It offers a validated and realistic flow model that serves as a fundamental tool for hydrological planning and sustainable management of the Loma de Úbeda aquifer system, addressing the challenges posed by climate change and intensive agricultural demands.
• The research quantitatively demonstrates the significant hydrogeological changes caused by long-term intensive pumping, including the drying of upper aquifers, the increasing reliance on deeper, poorer-quality water, and the shift from horizontal to predominantly vertical groundwater flow.
• The multidisciplinary approach, combining structural geology, geophysics, hydrogeology, and hydrochemistry, highlights the critical importance of comprehensive data integration for accurate aquifer characterization and modeling.

Funding

• Collaborative projects between the Guadalquivir basin organization, the Andalusian Regional Government, and the Spanish Geological and Mining Institute (IGME-CSIC).
• Project “Tectonic map of the Iberian Peninsula and the surrounding cordilleras”.
• Project CGL2015–71692-P.
• Project CGL2016–80687-R of the Agencia Estatal de Investigación (AEI) and European Fund for Economic and Regional Development (FEDER).

Citation

@article{GonzálezRamón2025Integration,
  author = {González-Ramón, Antonio and Heredia, Javier and Marín-Lechado, Carlos and Cifuentes, Víctor J.},
  title = {Integration of 3d geological models and groundwater flow models for the improvement of the management of complex multilayer aquifers under intensive exploitation. The case of the Loma de Úbeda (Southern Spain)},
  journal = {Journal of Hydrology Regional Studies},
  year = {2025},
  doi = {10.1016/j.ejrh.2025.102964},
  url = {https://doi.org/10.1016/j.ejrh.2025.102964}
}

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