GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 3.2 GNGTS 2024 Mapping surface/ground water interactons and embarkment compositon along the Po river with transient electromagnetcs G. Fiandaca 1 , A. Signora 1 , S. Galli 1 , J. Chen 1 , C. Compostella 1 , M. Gisolo 2 , A. Viezzoli 3 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) 3 EMergo S.r.l. , Cascina (Italy) In the last week of July 2023 the MapPo dimostratve survey has been carried out along the Po river and its embarkments with waterborne and ground-based electromagnetc methods, for more than 120 km of acquired data, as well as along 350 line km of airborne EM lines, across Lombardia, Veneto and Emilia Romagna (Fig. 1). The MapPo project aimed at mapping groundwater resources, and in partcular, with its waterborne and ground-based acquisiton, at studying the surface watwer/groundwater interaxctons and at mapping the internal compositon of the embarkments. The ground-based and waterborne acquisiton have been carried out twith the tTEM (Auken et al., 2019) and FloaTEM (Maurya et al., 2022) systems, respectvely (Fig. 2), while the airborne EM data have been acquired with the SkyTEM306HP system. Furthermore, 1.9 km of tme-domain direct- current and induced polarizaton (DCIP) data have been measured, with the ABEM Terrameter LS2 instrument. All data have been processed in EEMstudio, an opensource and freeware processing tool for electric and electromagnetc data (Sullivan et al., 2024; Fig. 1), and inverted with EEMverter (Fiandaca et al., 2024). Fig. 3 presents the tTEM and FloaTEM inversion models along 20 km of acquisitons, reaching more than 100 m of depth of investgaton, together with the comparison of the DCIP inversion. The FloaTEM inversions allow to discriminate the interactons between river and groundwater, thanks to the ability to map the impermeable (conductve) areas below the river, whicle the tTEM inversions are able to image the thickness of the clays in the embarkment, evidencing the fltraton areas mapped by the Po river basin authority. Furthermore, the presence of fossil saline water close to Ferrara, as well as sea water intrusion close to the Po di Goro are well imaged. The tTEM and FloaTEM inversions are also well comparable with the airborne EM inversions, thank also to the possibility to invert both ground-based, waterborne and airborne EM data in a unique inversion kernel, i.e. EEMverter.