GNGTS 2016 - Atti del 35° Convegno Nazionale

526 GNGTS 2016 S essione 3.2 In Figs. (3a and 3b) two resistivity models of profile No. 5, acquired before and after the commencement of the AR recharge activities, show quiet different resistivity distributions. These can be summarized in the following points: 1) articulated resistivity features (Fig. 3a) disappeared after AR initiation which supports water infiltration and percolation at least in the first 10 m below ground level; 2) formation resistivity values become homogeneous indicating the infiltrated freshwater could have been mixed with slightly saline water; 3) the post-AR resistivity model (Fig. 3b) give semi-quantitative indications about the effect that AR had on the depth increase of the freshwater-saltwater interface that in this specific case, has been quantified to be around 2 m. Further resistivity acquisitions along the same profile (ERT-5) were acquired and the gave similar results. Hence, for the time- being the preliminary results of the AR process seems promising. Discussion. In this short paper, the utility of the geoelectrical resistivity surveys, acquired in tomographic modality, in the subsurface characterization of lateral and vertical lithologic heterogeneities was tackled through the presentation of some salient results of the geoelectrical survey conducted at Copparo’s test site in the framework of the WARBO-Life+ EU project. The possibilities offered by modern georsistivity meters allowed their use not only for achieving lithologic information about the subsurface, although important, but also for the de-salinization monitoring of the artificial recharge process initiated in the test site. Repeated resistivity measurements have been capable of capturing some 2 m lowering of the freshwater-saltwater interface following one month of artificial recharge of the subsurface aquifers with freshwater from a nearby canal that was drawn through a pipe into a phytodepuration bit that conveys water to the nearby artificial lake once was quarry for clay. The good results obtained until now have proved the capability of the ERT technique to be used as a mid-to-long term non-invasive and indirect monitoring tool. References Archie G.E.; 1942: The electrical resistivity log as an aid in determining some reservoir characteristics. Trans A.I.M.E. 146, 54-62. Colombani N.; Mastrocicco M;.Dinelli E.; 2015: Trace elements mobility in a saline coastal aquifer of the Po river lowland (Italy). Journal of Geochemical Exploration, vol. 159, 317–328 Constable, S. C.; Parker R. L.; Constable C. G.; 1987: Occam’s inversion, A practical algorithm for generating smooth models from electromagnetic sounding data, Geophysics, 52:289–300. DeGroot-Hedlin C.; Constable, S.; 1990: Occam’s inversion to generate smooth, twodimensional models form magnetotelluric data. Geophysics, 55:1613-1624. Ewing R.P.and HuntA.G.; 2006: Dependence of the electrical conductivity on saturation in real porous media. Vadose Zone Journal 5 (2), 731-741. Kuras, O., D. Beamish, P.I. Meldrum, and R.D. Ogilvy. 2006. Fundamentals of the capacitive resistivity technique. Geophysics. 71:G135. Loke M.H., Barker R.D.; 1996: Rapid least-squares inversion of apparent resistivity pseudosections by a quasi- Newton method. Geophysical Prospecting 44, 131–152. Nieto Y. D.G.; Accaino F.; Affatato A.; Barbagallo A.; Baradello L.; Coren F.; Paganini P.; Vaccaro C.; Abu Zeid N.; Leis M.; Santarato G.; Farina S.; Gruppioni M.; 2015: Innovative technologies for the sustainable management of water resources: the WARBO (WAter Re-BOrn) project Bollettino di Geofisica Teorica e Applicata vol. 53 Iusse 2; 253 – 260 Pezzi M.; Chicca M.; Vaccaro C.; Nieto Y. D.G.; Rota E.; Lanfredi M.; Pepi S.; Leis M.; 2015:Monitoring Aquifer Quality for Artificial Recharge within the WARBO Project Procedia Engineering vol. 89. 1235 – 1240. SciarraA.; Cantucci B.; Abu Zeid N.; Vaccaro C.; Quattrocchi F.; 2015: Geochemical and Geomorphological Analyses on Liquefaction Occurred During the 2012 Emilia Seismic Sequence. In “Engineering Geology for Society and Territory – Volume 5: Urban Geology, Sustainable Planning and Landscape Exploitation”G. Lollino, A. Manconi, F. Guzzetti, M. Culshaw, P. Bobrowsky and F. Luino (eds), 1091-1095. Schoen J.H.; 1996: Physical Properties of Rocks. Handbook of Geophysical Exploration, Vol. 18. Pergamon Press, Inc.