GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 3.2 GNGTS 2024 Characterizing groundwater springs in the I tal ian Alps : an integrated geologi cal , geophysical, and hydrogeological approach A. Lucchelli 1 , A. Signora 1 , F. Daut 1 , S. Galli 1 , M. Gisolo 2 , G. Fiandaca 1 1 The EEM Team for Hydro & eXploraton, Department of Earth Sciences “Ardito Desio”, Università degli Studi di Milano, Milano, Italy 2 a2a Ciclo Idrico s.p.a., Brescia, Italy Spring water is one of the major sources of drinking water for local communites throughout the Italian Alps and in mountain areas worldwide (ISTAT, 2020; United Natons, 2022). As water demand and pressure on groundwater resources increase in a context of fast-changing climate, there is a growing commitment to assess groundwater availability and develop sustainable water supply strategies. The proper management of groundwater resources requires the characterizaton of the aquifer systems. In this regard, karst terrains pose unique challenges due to their complex and heterogeneous nature. This study focuses on the assessment of an aquifer system in a karst- fssured mountain environment, by employing an integrated approach based on three pillars: geology, geophysics, and hydrogeology. The study area, located in the Brescia Prealps (northern Italy), is characterized by a Lower-Middle Triassic succession with a fold-and-thrust architecture, typical of the Southern Alps domain, complicated by the presence of faults (Boni & Cassinis, 1973). The geological pillar is based on a 3D geological-structural model developed using both bibliographic data and feld observatons. This model serves as the foundaton for understanding the spatal distributon of geological formatons and the major tectonic lineaments. The geophysical pillar is built on both ground-based geophysics (classic electrical tomography, ERT, and innovatve transient EM methods, i.e. Loupe TEM (Street et al., 2018)) and on densely-spaced airborne electromagnetcs (AEM) (Fig. 1). The hydrogeological pillar consists of spring discharge data, groundwater chemical analysis, and stable isotope analysis of Oxygen, Hydrogen, and Carbon (Fig. 1). Where geological data is sparse, 3D geological modeling can be used to derive a homogeneous, realistc representaton of geological features over the entre study area. In this study it was performed using the GeoModeller sofware by Intrepid Geophysics (Calcagno et al., 2008). Geophysical surveys, on the other hand, play a key role in capturing the subsurface heterogeneity and identfying preferental fow paths within the rock volumes. Together, these methods provide the informaton needed to understand aquifer architecture. To model the electric and electromagnetc data the EEMverter inversion sofware has been used (Fiandaca et al., 2023). For the mutual calibraton of geological and geophysical data, two rules