Redaelli et al. (2026) Changes in irrigation practices may deplete aquifers faster and more severely than meteorological droughts: A numerical modeling approach

Identification

• Journal: Journal of Hydrology
• Year: 2026
• Date: 2026-03-19
• Authors: Agnese Redaelli, Tullia Bonomi, Davide Sartirana, Gianfranco Sinatra, Daniel T. Feinstein, Randall J. Hunt, Marco Rotiroti, Chiara Zanotti
• DOI: 10.1016/j.jhydrol.2026.135337

Research Groups

• Department of Earth and Environmental Sciences, University of Milano-Bicocca, Milan, Italy
• Acque Bresciane S.r.l. SB, Rovato, Italy
• Department of Geoscience, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
• Department of Geoscience, University of Wisconsin-Madison, Madison, WI, USA

Short Summary

This study quantitatively assessed the drivers of aquifer depletion in an intensively irrigated system, finding that changes to more efficient irrigation practices, which reduce irrigation return flow, have a more severe impact on groundwater resources than meteorological droughts.

Objective

• To quantitatively assess whether meteorological droughts or changes to more efficient irrigation practices (reducing return flow) are the major drivers of aquifer depletion in intensively irrigated agricultural areas.

Study Configuration

• Spatial Scale: Site-specific, intensively irrigated hydrogeological system in the Po plain, Italy.
• Temporal Scale: Two-year simulations (2015-2017 baseline, and two-year hypothetical scenarios).

Methodology and Data

• Models used: Three-dimensional combined steady-state and transient numerical groundwater flow model.
• Data sources: Groundwater level and groundwater-river exchange flow data (used for model calibration).

Main Results

• A two-year meteorological drought scenario resulted in a total groundwater storage loss of 2.34 × 10^5 m^3/d, while preserving the seasonal patterns of groundwater dynamics.
• A scenario simulating a change from surface irrigation to more efficient drip irrigation (reducing return flow) led to a greater groundwater storage loss of up to 2.77 × 10^5 m^3/d and disrupted seasonal patterns, critically impacting lowland springs and connected surface water bodies.
• Surface-water irrigation return flow is crucial for sustaining groundwater balance and the ecological functioning of groundwater-dependent systems in intensively cultivated areas.
• Policymakers' adaptation measures to address surface water scarcity (e.g., promoting efficient irrigation) may have a more significant and detrimental impact on groundwater resources than the direct effects of climate change itself.

Contributions

• Provides a quantitative comparison of the impacts of meteorological drought versus changes in irrigation practices on aquifer depletion.
• Highlights the critical role of irrigation return flow in maintaining groundwater balance and supporting groundwater-dependent ecosystems in agricultural regions.
• Offers scientific evidence to inform policymakers about the potentially more severe, unintended consequences of certain climate change adaptation strategies on groundwater resources.

Funding

• Funding information is not explicitly provided in the text of the paper.

Citation

@article{Redaelli2026Changes,
  author = {Redaelli, Agnese and Bonomi, Tullia and Sartirana, Davide and Sinatra, Gianfranco and Feinstein, Daniel T. and Hunt, Randall J. and Rotiroti, Marco and Zanotti, Chiara},
  title = {Changes in irrigation practices may deplete aquifers faster and more severely than meteorological droughts: A numerical modeling approach},
  journal = {Journal of Hydrology},
  year = {2026},
  doi = {10.1016/j.jhydrol.2026.135337},
  url = {https://doi.org/10.1016/j.jhydrol.2026.135337}
}