Gravity Modelling of Permafrost in Alpine Environments

The Sadole Valley, nestled in northeastern Italy's Trento province, is home to the Sadole rock glacier. The Sadole Valley is part of the Lagorai mountain range and primarily consists of porphyritic rocks from the Permian period. These ancient volcanic formations, rich in quartz and feldspar, have undergone extensive metamorphism over time, shaping the valley’s rugged terrain and influencing its hydrology. Despite human presence, the Sadole Valley has retained its pristine nature. It can be accessed from Ziano di Fiemme through the village of Bosin and features elevations ranging from 1,321 to 1,764 meters. Additionally, it plays a role in the regional hydrological system as a tributary of the Adige River. Hence, geophysical investigations, including electrical resistivity tomography (ERT), have detected high-resistivity zones that suggest the presence of frozen ground. An infiltration experiment conducted in June 2022 revealed that the permafrost layer functions as an aquitard, restricting water infiltration and channeling it along specific subsurface pathways. These discoveries underscore the significant influence of permafrost on the hydrological processes within the Sadole Valley. Permafrost, which refers to ground that remains frozen at or below 0°C for a minimum of two consecutive years, plays a crucial role in alpine hydrology by acting as an aquitard that affects groundwater flow and storage. As temperatures rise, permafrost degradation can result in increased groundwater movement and greater risks of slope instability. To study subsurface structures and permafrost distribution, geophysical techniques such as gravity surveys and electrical resistivity tomography (ERT) are widely utilized. Gravity surveys identify variations in the Earth's gravitational field caused by differences in subsurface density, whereas ERT assesses electrical resistivity by introducing an electric current into the ground and analyzing the resulting voltage responses. These methods have proven effective in numerous alpine environments for mapping permafrost and evaluating its influence on hydrological processes. Although geophysical techniques have advanced, accurately mapping the internal structure of rock glaciers and understanding their hydrological behavior remains challenging. The Sadole rock glacier features a complex subsurface with a mix of frozen and unfrozen layers, making geophysical data interpretation difficult. In this study, we will explore three primary models along with an additional alternative model to assess their ability to represent the most logical and realistic scenario. Through a comprehensive analysis, we aim to evaluate and compare these models to determine which one most accurately reflects the actual conditions under observation. This approach will help us gain deeper insights into the underlying processes and improve our understanding of the factors influencing the system under study.