Waterborne and on-land electrical surveys to suggest the geological evolution of a glacial lake in NW Italy

Abstract

Geophysical surveys on and around the Candia Lake, located NE of Turin (NW Italy), in the internal depression of the Ivrea Morainic Amphitheatre (IMA) right frontal sector, are reported in this paper. The surveys were intended to obtain a geophysical characterization of the lakebed, to investigate the interconnection paths between surface water and groundwater and to be used as a first general survey for suggesting the geological processes which lead to the actual morphology. An extensive waterborne Continuous Vertical Electrical Soundings (CVES) survey consisting of 15 profiles, with a total length of about 19 km of acquisition, was carried out on the lake surface. The processing of the acquired profiles with a Laterally Constrained Inversion (LCI) approach lead to the reconstruction of the lakebed sediments distribution, down to 10 meters depth. Self Potential (SP) data recorded on the lake surface have also been analyzed. Moreover, to verify the areal distribution of the deposits, three Electrical Resistivity Tomographies (ERT) were carried out on land near the northern and southern shore of the lake. The combination of the geophysical surveys results with hydrogeological information and geological observations and interpretations allowed the characterization of the submerged deposits, the probable identification of the main areas of groundwater recharge and the preliminary reconstruction of the lake genesis