Najmaddini et al. (2025) Modeling groundwater responses to the Persian Gulf water transfer and deficit irrigation in the Sirjan Plain

Identification

• Journal: Journal of Sedimentary Environments
• Year: 2025
• Date: 2025-10-11
• Authors: Mohammad Najmaddini, Somaye Janatrostami
• DOI: 10.1007/s43217-025-00267-0

Research Groups

• Department of Water Engineering, Faculty of Agricultural Sciences, University of Guilan, Rasht, Iran

Short Summary

This study utilized the MODFLOW model to evaluate groundwater responses to the Persian Gulf water transfer and deficit irrigation in the Sirjan Plain, Iran, finding that while both interventions mitigate depletion, integrated management is essential for long-term aquifer sustainability.

Objective

• To quantify the effects of the Persian Gulf seawater transfer project and deficit irrigation strategies (25% and 40% reductions) on the Sirjan Plain aquifer's groundwater levels and sustainability over a 5-year period (2019–2023).

Study Configuration

• Spatial Scale: Sirjan Plain aquifer, covering 2336.3 square kilometers. The model domain was discretized into a finite-difference grid of 37 rows and 65 columns, with each cell measuring 1500 meters by 1500 meters.
• Temporal Scale: A 5-year simulation horizon (2019–2023). The model was calibrated for steady-state conditions (October 2017) and transient conditions (October 2017 to September 2018), and validated for 2019–2020.

Methodology and Data

• Models used: MODFLOW (a three-dimensional, cell-based finite-difference groundwater flow model developed by the U.S. Geological Survey).
• Data sources: Topographic maps, geological surveys, hydrogeological field investigations, groundwater-level monitoring wells, precipitation records, pumping tests, Digital Elevation Model (DEM), and groundwater abstraction data from exploitation wells.

Main Results

• Under the baseline scenario, groundwater levels in the Sirjan Plain aquifer showed a continuous decline, with localized drawdowns exceeding 8 meters over the 5-year period (2019–2023). The aquifer has an estimated annual deficit of approximately 69 million cubic meters.
• The Persian Gulf water transfer project provided partial relief, increasing groundwater levels in affected wells (e.g., Wells 11 and 13) by 0.86 meters and 0.77 meters, respectively, compared to the baseline.
• Deficit irrigation strategies yielded larger improvements: a 25% reduction in irrigation during May-July resulted in a net rise of 1.77 meters in groundwater levels over 5 years, while a 40% reduction led to an increase of up to 1.92 meters. These strategies generated monthly water savings ranging from 3000 to 67,000 cubic meters.
• Despite these benefits, the combined measures of water transfer and deficit irrigation only reduced the rate of groundwater depletion and did not achieve full aquifer stabilization.
• Model performance was robust: steady-state calibration achieved an R² of 0.99, RMSE of 0.14 meters, and NRMSE of 12.83%; transient calibration achieved an R² of 0.78, RMSE of 0.57 meters, and NRMSE of 3.4%.

Contributions

This study is the first to quantify the combined impacts of the Persian Gulf water transfer project and deficit irrigation strategies on the Sirjan Plain aquifer using a calibrated three-dimensional MODFLOW model. It provides evidence-based guidance for policymakers and stakeholders to balance industrial and agricultural water demands, refine allocation strategies under water stress, and advance sustainable groundwater management in arid regions. By linking rigorous hydrological modeling with policy-relevant scenario analysis, the research informs debates on large-scale water transfers and their consequences for groundwater sustainability.

Funding

The authors declare that no funds, grants, or other support were received during the preparation of this manuscript.

Citation

@article{Najmaddini2025Modeling,
  author = {Najmaddini, Mohammad and Janatrostami, Somaye},
  title = {Modeling groundwater responses to the Persian Gulf water transfer and deficit irrigation in the Sirjan Plain},
  journal = {Journal of Sedimentary Environments},
  year = {2025},
  doi = {10.1007/s43217-025-00267-0},
  url = {https://doi.org/10.1007/s43217-025-00267-0}
}