GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 3.2 ___ GNGTS 2023 geophysical measures. The long-term aim is to understand the temporal evolution of the permafrost and the effects of climate change on the sub-permafrost aquifer. The geophysical surveys took place in the summer of 2022 and focused on ERT and GPR acquisitions. The investigated areas were the Bayelva basin (on the left in Fig. 1) and the mine area (on the right). In the eastern part of the investigated area within the Bayelva basin, geophysical acquisitions overlapped the alignment of four piezometers (2 m deep) realized by the ICEtoFLUX project for the physical-chemical and hydrological monitoring of the active layer. The ERT profiles were acquired with 10 m of spacing between the electrodes in order to characterize the deep features, such as the permafrost thickness and the sub-permafrost aquifer. Moreover, 1 m of electrode spacing was adopted in specific areas to inspect, with higher resolution, the active layer and the supra-permafrost aquifer. Around 8.3 km of electric lines were carried out. These ERT profiles are shown in Fig. 1 (yellow lines). GPR measurements with 40 MHz and 400 MHz antennas were carried out in the area of the Climate Change Tower, close to the four piezometers aforementioned, for a total of around 2 km of GPR lines. Coincident ERT and GPR profiles with different acquisition settings were designed along the line of piezometers in order to correlate the geophysical results with the geochemical data and water table information coming from the piezometer monitoring (see Fig. 1). Fig. 1 – Map of the geophysical campaign carried out in Ny-Ålesund (Svalbard) in the summer of 2022. The ERT profiles are plotted in yellow and the GPR profiles in green. The investigated area on the west is the Bayelva river basin, while that on the east is the former mine. The piezometers are indicated with white numbers. The red cross is a recent borehole (48.5 m deep). The blue circle indicates the position of a spring (Haldorsen and Heim, 1999).