Assessment and comparison of thermal stabilisation measures at an Alpine permafrost site, Switzerland

Abstract. Global warming provokes permafrost thawing, which leads to landscape changes and infrastructure damage, problems that have intensified worldwide in all permafrost regions. This study numerically investigates the impact of different thermal stabilization methods to prevent or delay permafrost thawing. To test different technical methods, an alpine mountain permafrost site with nearby infrastructure prone to damage is investigated. Model simulations represent the one-dimensional effect of heat fluxes across the complex system of snow-ice-permafrost layers, and the impact of passive and active cooling, including engineered energy flux dynamics at the surface. Results show the efficiency of different passive, active, and combined thermal stabilisation methods, in influencing heat transfer, temperature distribution, and the seasonal active layer thickness. Investigating each component of thermal stabilization helps quantify the efficiency of each method and determine their optimal combination. Passive methods despite provide efficient cooling in winter, due to heat transfer to the atmosphere, are less efficient as the active layer thickness remains over 1 m. Conductive heat flux regulation alone takes several years to form a stable frozen layer. Active, when powered with solar energy, cooling decreases the active layer thickness to a few decimetres. The combination of active and passive cooling, together with conductive heat flux regulation, performs best and allows excess energy to be fed into the local grid. Findings of this study show ground temperature and permafrost evolution at a representative alpine site under natural and thermally stabilized conditions, contributing to understanding potential and limitations of stabilization systems and formulate recommendations for optimal application.