Airborne EM in Northern Italy for sustainable and resilient management of groundwater resources

Climate change and anthropogenic pollution pose a significant challenge to the management of groundwater resources in northern Italy, where in 2022 alone rainfall decreased by 40% compared to the average of the previous 30 years and 67% of the utilized agricultural area is vulnerable to nitrate pollution. To face these challenges, starting in the spring of 2021, A2A Ciclo Idrico initiated a large-scale Airborne electromagnetics (AEM) campaign for mapping the groundwater resources in the Brescia province, Italy, consisting of more than 2000 linear kilometers of AEM data flown over an area of approximately 200 km2. This mapping campaign is the largest AEM campaign carried out in Italy for groundwater management, both in terms of extension and data density. Despite of the large anthropization of Brescia province, with the related problems of inductive couplings that disturb AEM data in the vicinity of buildings and infrastructures, excellent resistivity models have been retrieved in the flown areas, in a range of depths between 300 meters to 400 meters, thanks to careful data processing. This has allowed to map the groundwater resources with unprecedented coverage and resolution, both discovering new aquifers and highlighting their vulnerability. In particular, pathways for nitrate contamination in existing wells have been imaged, and the location for a new well for public water supply has been identified within an extended aquifer overlain by a clay layer that protects against pollution percolating from shallower aquifers. Moreover, 3D geological and hydrogeological models informed by AEM have been constructed in the valley of the Chiese river, and incorporated in a groundwater flow model of the area. These results triggered an even larger AEM campaign currently ongoing over all the plain and a mountainous sector of Brescia province, which we believe are the beginning of a paradigm shift in groundwater management in Italy towards resilient and sustainable exploitation of geo resources.