GNGTS 2018 - 37° Convegno Nazionale

GNGTS 2018 S essione 3.2 689 isosurface of electrical resistivity values higher than 5 kOhm m (Fig. 3, in green). Given the resistivity values, this promontory can be likely interpreted as the submerged and buried prosecution of the compact rocky edge outcropping on the western shore of the pond. The areas of the pond bottom outside this isosurface (N and S edges of the pond) can be likely composed of more fractured bedrock or coarse debris bodies. Within the promontory, some areas with even higher resistivity values (>10 kOhm m, Fig. 3, in yellow) were found to the NE and NW of the pond perimeter. These extremely high resistivity values have been attributed in literature to the presence of permafrost or ice bodies (e.g. Schrott and Sass, 2008). These high-resistivity regions correspond to negative SP anomalies (-10 mV to -25 mV), while a global positive SP distribution is found in the central part of the pond (0 mV to 25 mV). The interpretation of the overall electrical parameter distribution, as well as the acquired radargrams, is still debated and under investigation. Acknowledgements. We would like to thank Consorzio di Miglioramento Fondiario di Gressoney (Aosta) and MonteRosa-ski. This research has been partially developed in the European Regional Development Fund in Interreg Alpine Space project Links4Soils (ASP399): Caring for Soil-Where Our Roots Grow (http://www.alpine-space.eu/ projects/links4soils). The Authors would like to thank the management of the “Rifugio Gabiet” for their warm attitude with the field crew. References Boeckli, L., Brenning, A., Gruber, S., Noetzli, J.; 2012: Permafrost distribution in the European Alps: calculation and evaluation of an index map and summary statistics, The Cryosphere, 6, 807-820. Buraschi, E., Salerno, F., Monguzzi, C., Barbiero, G., Tartari, G.; 2005: Characterization of the Italian lake-types and identification of their reference sites using anthropogenic pressure factors, Journal of Limnology, 64(1), pp. 75-84. Catalan, J., Camarero, L., Felip, M., Pla, S., Ventura, M., Buchaca, T., Bartumeus, F., de Mendoza, G., Miró, A., Casamayor, E.O., Medina-Sánchez, J.M., Bacardit, M., Altuna, M., Bartrons, M., De Quijano, D.D.; 2006: High mountain lakes: Extreme habitats and witnesses of environmental changes, Limnetica, 25(1-2), pp 551-584. Carpenter, S.R., Benson, B.J., Biggs, R., Chipman, J.W., Foley., J.A., Golding, S.A., Hammer, R.B., Hanson, P.C., Johnson, P.T.J., Kamarainen, A.M., Kratz, TK., Lathrop, R.G., McMahon, K.D., Provencher, B., Rusak, J.A., Solomon, C.T., Stanley, E.H., Turner, M.G., Vander Zanden, J.M., Wu, C-H., Yuan, H.; 2007: Understanding regional change: A comparison of two lake districts, Bioscience, 57, pp. 323-335. Fig. 3 - Results of the 3D inversion of the 10 ERT profiles: isosurface at 5 kOhm m (in green) and 10 kOhm m (in yellow). The pond bathymetry obtained from GPR is overlapped with the white-blue color scale. The pond perimeter is highlighted with the black line.