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Intensive irrigation buffers groundwater declines in key European breadbasket

Nature Water volume 3, pages 683–692 (2025)Cite this article

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Abstract

The Po Plain in northern Italy is a critical agricultural region and one of the largest water users in the European Union. Recent dry conditions have put future water resource availability into question. This study examines spatio-temporal variations in groundwater storage observed by the Gravity Recovery and Climate Experiment satellites and more than 1,000 groundwater wells from 2002 to 2022. We find that the rate of groundwater storage decline more than doubled from 2015 to 2022 as compared to the 2002–2022 rate. We also show that seasonal and long-term groundwater availability is strongly influenced by irrigation activities. Groundwater storage in irrigated areas is highly correlated to snow accumulation in the Alps and shows more stability as compared to non-irrigated areas, which experience dramatic declines during drought years. This indicates that inefficient irrigation practice, using water largely supplied by snowmelt, recharges underground aquifers and helps maintain high water tables, making aquifers underlying irrigated farmland resilient to the negative consequences of drought. These findings can help guide climate-driven adaptations to irrigation systems that account for the impact on groundwater recharge.

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Fig. 1: Po Plain study region.
Fig. 2: GWS anomalies with respect to the mean derived using the GRACE and GFO mass balance approach.
Fig. 3: Total change in GWS calculated from in situ groundwater-level time series.
Fig. 4: Seasonal variations in groundwater level.
Fig. 5: Yearly GWS change in the unconfined aquifer with respect to 2002.

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Data availability

GRACE JPL mascon solutions can be downloaded from https://podaac.jpl.nasa.gov/dataset/TELLUS_GRAC-GRFO_MASCON_CRI_GRID_RL06.1_V3. GLDAS models VIC, Noah and CLSM can be downloaded from https://disc.gsfc.nasa.gov/datasets?keywords=GLDAS. GLEAM4 can be downloaded via SFTP at https://www.gleam.eu. ERA5-Land can be downloaded from https://cds.climate.copernicus.eu/cdsapp#!/dataset/10.24381/cds.68d2bb30?tab=form. SPEI can be downloaded from https://spei.csic.es/map/. Monthly Po River discharge data provided by D. Zanchetin are available via Zenodo at https://doi.org/10.5281/zenodo.7225699 (ref. 63). Monthly precipitation is available from NASA’s IMERG project at https://disc.gsfc.nasa.gov/datasets/GPM_3IMERGM_07/summary?keywords=%22IMERG%20final%22. SWE is provided by the Meteorological Reanalysis Italian Dataset at https://merida.rse-web.it. Monthly seasonal mean groundwater levels and trends for 1,024 groundwater wells across the northern Italian plains are available via Zenodo at https://doi.org/10.5281/zenodo.14013762 (ref. 66).

Code availability

All data were processed in MATLAB. Wavelet software was provided by C. Torrence and G. Compo and is available at http://atoc.colorado.edu/research/wavelets/.

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Acknowledgements

We thank the following monitoring agencies: Agenzia Regionale per la Protezione dell’Ambiente (ARPA) Lombardia, L’Agenzia regionale per la prevenzione, l’ambiente e l’energia dell’Emilia Romagna (ARPAE), Agenzia Regionale per la Prevenzione e Protezione Ambientale del Veneto (ARPAV) and Agenzia Regionale per la Protezione Ambientale (ARPA) Piemonte for providing the in situ groundwater observation well time series and lake-level change time series. NASA grants 80NSSC20K1240 and 80NSSC22K1831 and the Hellman Fellows Fund supported G.C. and M.G., European Space Agency (ESA) grant 4000136272/21/I-EF supported C.M. and the Historically Black Colleges and Universities-Berkeley Environmental Scholars for Change Program supported D.W.

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Authors and Affiliations

  1. Department of Environmental Science, Policy and Management, University of California, Berkeley, Berkeley, CA, USA

    Grace Carlson, Andrew Wilder, Destinee Whitaker & Manuela Girotto

  2. Research Institute for Geo-Hydrological Protection, National Research Council CNR, Perugia, Italy

    Christian Massari

  3. Department of Earth and Environmental Sciences, University of Milano-Bicocca, Milano, Italy

    Marco Rotiroti & Tullia Bonomi

  4. Water Research Institute, National Research Council CNR, Montelibretti, Italy

    Elisabetta Preziosi

  5. Spelman College, Atlanta, GA, USA

    Destinee Whitaker

  6. West Atlanta Watershed Alliance, Atlanta, GA, USA

    Destinee Whitaker

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Contributions

G.C., M.G. and C.M. conceived and designed the experiments. G.C. performed the experiments. G.C., M.G., C.M., M.R., T.B., E.P. and D.W. analysed the data. G.C., M.G., C.M., M.R., T.B. and A.W. contributed materials and analysis tools. G.C. led the writing of the paper with all authors making contributions to the writing and editing process.

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Correspondence to Grace Carlson.

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The authors declare no competing interests.

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Nature Water thanks Jenna Dohman, David Ketchum and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Extended data

Extended Data Fig. 1 Number of observations used to calculate ∆GWS for each time step for each time series in Fig. 5.

The High Plain and Low Plain (dark blue and orange, respectively) correspond to ∆GWS time series in Fig. 5a. Lombardia irrigated and Lombardia not irrigated (yellow and purple, respectively) correspond to the time series in Fig. 5b. Veneto and Piemonte (green and purple, respectively) correspond to the time series in Fig. 5c and Emilia Romagna (red) correspnds to the time series in Fig. 5d.

Extended Data Table 1 Spearman correlation (ρ) between yearly GWS change and peak SWE, precipitation, and discharge (Q)
Full size table

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Carlson, G., Massari, C., Rotiroti, M. et al. Intensive irrigation buffers groundwater declines in key European breadbasket. Nat Water 3, 683–692 (2025). https://doi.org/10.1038/s44221-025-00445-4

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