Intensive agricultural irrigation can significantly enhance the resilience of groundwater resources in the Po Valley, even in the face of increasing summer droughts caused by climate change. This is the conclusion of a study resulting from a collaboration between the National Research Council of Italy (CNR), the University of Milano-Bicocca, and the University of Berkeley, recently published in the journal Nature Water.
The research analyzed satellite data collected between 2002 and 2022 from NASA’s GRACE mission—now concluded—which aimed to improve the understanding of climate change through the monitoring of global water mass movements. The study also drew on data from a network of over 1,000 groundwater monitoring wells.
Through these data, the research team traced the evolution of underground water resources, revealing that—despite a general decrease in water table levels—areas with intensive irrigation showed greater stability, thanks to recharge induced by infiltration of excess irrigation water. This is because irrigation in these areas is generally supported by surface waters drawn from Alpine rivers and lakes (e.g., Lake Maggiore, Lake Garda), which are themselves fed by snowmelt.
The study also demonstrated a positive correlation between groundwater levels in the plains and snow accumulation in the Alps. These results indicate that while irrigation is a water-intensive practice, it can support aquifer recharge through percolation of surplus irrigation water.
The contribution from CNR institutes focused particularly on the hydrological analysis of regional data:
“This research highlights the importance of understanding the water balance in agriculture, especially now that Alpine snow cover is becoming increasingly unpredictable,” says Christian Massari of CNR-IRPI.
The University of Milano-Bicocca contributed to the estimation of hydrogeological parameters and the construction of the conceptual model describing groundwater circulation:
“In this context, the critical factor is potential winter drought, which would reduce the recharge of rivers and lakes and, in turn, limit the feasibility of summer irrigation that recharges the aquifers. As long as there is adequate snow coverage in winter, irrigation will help stabilize the aquifers—even during summer droughts,” explains Marco Rotiroti from the University of Milano-Bicocca.
The study underscores the urgency of evaluating the future sustainability of irrigation practices amid growing water scarcity, while also recognizing the potential positive role of certain agricultural practices in enhancing local water availability.
Carlson, G., Massari, C., Rotiroti, M., Bonomi, T., Preziosi, E., Wilder, A., Whitaker, D., Girotto, M. “Intensive irrigation buffers groundwater declines in key European breadbasket”. Nat Water (2025)