Estimation of groundwater storage loss using surface–subsurface hydrologic modeling in an irrigated agricultural region

Authors: ABBAS, SALAM - Colorado State University; BAILEY, RYAN - Colorado State University; WHITE, JEREMY - Intera, Inc; Arnold, Jeffrey; White, Michael

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/4/2025
Publication Date: 3/11/2025
Citation: Abbas, S.A., Bailey, R.T., White, J.T., Arnold, J.G., White, M.J. 2025. Estimation of groundwater storage loss using surface–subsurface hydrologic modeling in an irrigated agricultural region. Scientific Reports. https://doi.org/10.1038/s41598-025-92987-6.
DOI: https://doi.org/10.1038/s41598-025-92987-6

Interpretive Summary: Farmers in the Mississippi Alluvial Plain rely heavily on groundwater from the alluvial aquifer for irrigation, which has caused significant drops in water levels over time. This study using the SWAT+ model examined long-term changes in groundwater storage under wet, dry, and average conditions from1982-2020. The model links groundwater pumping directly to irrigation needs and simulates water flow and storage. The findings show clear declines in groundwater levels and flow in all conditions, with dry years seeing the largest declines. These results highlight the urgent need for better local management to address the ongoing depletion of groundwater resources.

Technical Abstract: The demand for groundwater resources from the alluvial aquifer for agricultural irrigation has led to significant reductions in groundwater-level elevation over time. In this study, we use the hydrologic SWAT+ to quantify long-term changes in groundwater storage within the Mississippi Alluvial Plain in United States, wherein groundwater is used extensively for irrigation. We apply a linear quantile regression method to perform trend analysis for wet, dry, and average conditions for the 1982-2020 period. The SWAT+ model uses the gwflow module to simulate groundwater storage and groundwater-surface water interactions in a physically based spatially distributed manner, with groundwater pumping linked to field-based irrigation demand. Results indicate significant trends in storage and groundwater fluxes. In wet conditions, significant decline trends are noted in groundwater head (–18 mm/yr) and groundwater evapotranspiration (–0.7 mm/yr). Under dry conditions, trends are in groundwater head (–28 mm/yr), recharge (–5.5 mm/yr), and groundwater discharge (–5.5 mm/yr). For average conditions, decreases include groundwater head (–20.6 mm/yr), recharge (–6 mm/yr), and groundwater discharge (–9.3 mm/yr.). This underscores the significance of local management solutions.