Güz et al. (2025) Dynamic coupling of hydrogeology and human decision-making for sustainable groundwater management in Konya Closed Basin, Türkiye

Identification

• Journal: Journal of Hydrology Regional Studies
• Year: 2025
• Date: 2025-12-01
• Authors: Şanser Güz, İzel Uygur, Nadım K. Copty, Ali Kerem Saysel
• DOI: 10.1016/j.ejrh.2025.103013

Research Groups

• Graduate School of Engineering, The University of Tokyo, Japan
• Institute of Environmental Sciences, Boğaziçi University, Türkiye
• System Dynamics Group, Department of Geography, University of Bergen, Norway

Short Summary

This study develops and applies a coupled socio-hydrological model, integrating a process-based groundwater flow model (MODFLOW-UZF) with a system dynamics model (VENSIM), to simulate hydrogeological processes and human decision-making for sustainable groundwater management in the Konya Closed Basin, Türkiye. The research demonstrates that spatially and temporally disaggregated policy measures significantly enhance groundwater resource management by more accurately capturing human-hydrological feedback compared to stand-alone models.

Objective

• To develop and apply a coupled socio-hydrological model that integrates a process-based groundwater flow model (MODFLOW-UZF) with a system dynamics model (VENSIM) to simulate both hydrogeological processes and human decision-making.
• To test the impacts of various policy configurations, including crop pricing, extraction caps, and surface water transfers, for sustainable groundwater management.
• To gain insight into the complex feedback loops influencing groundwater use and for policy experimentation, aiding in the design of effective interventions aimed at achieving long-term groundwater sustainability.

Study Configuration

• Spatial Scale: Konya Closed Basin (KCB), Türkiye, covering an area of 50,000 km². The process-based model uses a uniform 10 km by 10 km grid. The system dynamics model focuses on the Çumra administrative district, an area of 2,200 km².
• Temporal Scale:
  • Historical calibration: January 2000 to December 2022 for the process-based model; 2004 to 2024 for the system dynamics model.
  • Prospective simulations: 2022 to 2040.
  • Model communication interval: 1 year.
  • Process-based model stress period: 1 month.
  • System dynamics model time unit: 1 year.

Methodology and Data

• Models used:
  • Process-based groundwater flow model (PBM): MODFLOW (McDonald and Harbaugh, 1988) coupled with the Unsaturated-Zone Flow (UZF1) module (Niswonger et al., 2006).
  • System Dynamics Model (SDM): VENSIM software.
  • Coupling framework: Python-based program utilizing PySD (Martin-Martinez et al., 2022) and FloPy (Bakker et al., 2016) libraries for bidirectional variable exchange.
• Data sources:
  • Historical groundwater level data from 29 long-term observation wells (for calibration).
  • Monthly precipitation data spatially interpolated from 18 meteorological stations.
  • Aquifer transmissivity estimated from 81 pumping tests using ordinary kriging.
  • Monthly groundwater extraction rates estimated from annual crop areas (Turkish Statistical Institutes, TUIK, 2023) and crop-specific water demands for the Konya region (TAGEM, 2017).
  • RCP8.5 climate scenarios for precipitation projections in prospective runs (Todaro et al., 2022).
  • Stakeholder input for system dynamics model development and policy formulation.

Main Results

• The coupled dynamic model (CDM) accurately captures both seasonal variability and long-term depletion trends in groundwater levels, outperforming stand-alone PBM and SDM. It reproduces the long-term depletion trend with a rate of 0.99 m/year, compared to 0.90 m/year for SDM and 0.51 m/year for PBM, and shows the most accurate mean monthly variability (0.161 m).
• Under a business-as-usual scenario (2022–2040), the CDM predicts a more severe and progressive decline in groundwater head (964 m) compared to the SDM (968 m), leading to fewer active wells and lower agricultural yields and profits.
• Policy scenarios (e.g., crop rotation, well drilling ban, extraction caps, surface water transfers, price adjustments) show groundwater recovery in both models, but the CDM consistently projects more conservative outcomes.
• Spatially and temporally targeted policies, such as directing surface water transfers to vulnerable northern Çumra or intensifying extraction quotas during summer, are more effective in mitigating groundwater depletion than aggregate, basin-wide policies.
• Policies with full spatial and temporal disaggregation yield the highest groundwater recovery (981 m) with minimal economic cost, indicating that policy effectiveness increases with the degree of disaggregation.

Contributions

• Development of a novel bidirectional coupled socio-hydrological model (CDM) that integrates a process-based groundwater flow model (MODFLOW-UZF) with a system dynamics model (VENSIM) using a Python-based framework.
• Demonstrates the enhanced capability of integrated modeling to overcome the limitations of stand-alone models by combining the spatial and temporal detail of process-based hydrology with the endogenous human decision-making of system dynamics.
• Provides a comprehensive tool for policymakers to develop effective groundwater management strategies by addressing both hydrological and socio-economic dimensions with spatiotemporal detail.
• Highlights the critical importance of spatial and temporal disaggregation in policy design, showing that targeted interventions are significantly more effective for sustainable groundwater resource management than uniform basin-wide measures.
• Offers new insights into the complex feedback loops between aquifer conditions and farmer decisions, illustrating how socio-economic and hydrological drivers jointly shape groundwater dynamics.
• The coupling framework is adaptable to other data-scarce, densely-irrigated regions facing similar groundwater over-extraction issues.

Funding

• InTheMed project (grant agreement No 1923)
• OurMed project (grant agreement No 2222)
• Partnership for Research and Innovation in the Mediterranean Area (PRIMA)
• European Union’s HORIZON 2020 research and innovation funding programme

Citation

@article{Güz2025Dynamic,
  author = {Güz, Şanser and Uygur, İzel and Copty, Nadım K. and Saysel, Ali Kerem},
  title = {Dynamic coupling of hydrogeology and human decision-making for sustainable groundwater management in Konya Closed Basin, Türkiye},
  journal = {Journal of Hydrology Regional Studies},
  year = {2025},
  doi = {10.1016/j.ejrh.2025.103013},
  url = {https://doi.org/10.1016/j.ejrh.2025.103013}
}