Abstract ID: 3.11009 | Accepted as Talk | Talk/Oral | TBA | TBA

Climate change is affecting mountain regions and projections suggest that temperatures in these regions will rise faster than the global average. This is leading to shifts in local weather conditions with an increase in the frequency and intensity of precipitation, especially in winter, along with a reduction in snow cover, glacial melt, permafrost thawing and more rainfall on frozen ground. These changes are expected to affect hydrological processes, particularly the interaction between precipitation and frozen soils, with direct implications for surface runoff, mountain water hydrographs, slope stability and natural hazards. Traditionally considered impermeable, frozen soils exhibit complex behaviour under evolving weather conditions. When precipitation falls on frozen soil, two scenarios may unfold. In one, warmer precipitation gradually thaws the upper soil layer, thereby increasing infiltration and mobilising water that could intensify groundwater flow. In the other, precipitation may freeze on contact – either forming a soil surface ice shield or freezing within the soil matrix and obstructing the pore structure. Both outcomes result in reduced infiltration and amplified surface runoff, potentially triggering floods and landslides. This intricate thermohydraulic interplay determines the balance between infiltrated precipitation and runoff, ultimately influencing the timing and volume of mountain waters. Current numerical models for hydrological systems, drainage, or mass flow do not adequately account for the temperature-dependent variability of soil permeability – a factor that will be critical for future modelling efforts and for accurately representing resultant flow components. This study presents novel insights from an experimental setup designed to simulate the processes of precipitation infiltration and surface runoff for frozen soil conditions. An advanced irrigation system provides uniform rainfall to a tiltable soil body (mass 1500 kg), while a sophisticated climate chamber maintains controlled conditions that replicate realistic freezing processes. High-resolution sensors capture detailed precipitation data and enable three-dimensional visualisation of soil temperature and moisture dynamics during freeze-thaw cycles. Complementary data from an Alpine field site further validate the experimental findings. These results are essential for refining hydrological models and mitigating natural hazards in mountain regions under a changing climate.