A combined geophysical survey for hydrogeological purposes in north-eastern Italy

An extended geophysical survey using electromagnetic and electrical methods (EM-34, VLF and YES) has been carried in a mountainous area in North-Eastern Italy (Southern Alps). The purpose of the geophysical survey was to provide information on the subsoil for the best location of water wells. Several profiles were performed using a frequency domain low induction system with 20 mand 40 m separation distance between the two coils in order to obtain information on the electrical resistivity at the target depth (about 30-50 m). The resistivity values were calibrated using the results of some vertical electrical soundings. The electromagnetic survey was completed with VLF profiles along the same profiles of the low induction survey. Attention was focused on the faults, which are the potential groundwater path-ways, to their direction and structural features (infilling, opening, etc.). The geophysical results were calibrated through the drilling of a borehole, which confirmed the reliability of the geological model.