Influences of snow cover on thermal and mechanical processes in steep permafrost rock walls: internal response

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Significant achievements have recently been made for thermal modelling of idealised undisturbed permafrost bedrock. However, most permafrost rock walls inherit significant snow accumulation, which often dominate permafrost evolution and fluctuation throughout time. Climate change alters snow timing, duration and thickness which all influence permafrost development. Our project aims at deciphering snow control in steep permafrost rocks and its sensitivity to climate change. We target at developing 1) a novel methodological/modelling framework to investigate snow forcing, 2) process understanding for snow impact quantification and 3) future scenarios for estimating the impact of snow cover changes in steep permafrost rock walls. Part 2 focuses on surface heat/water flow characterization using continuous snow cover quantification, terrestrial laser scanning (TLS), the calibration of physical snow properties (snow pits) and surface rock temperature (temperature loggers) measurements. Part 1 investigates the subsurface impact of snow on the thermal and mechanical behaviour inside rockwalls using laboratory-calibrated 3D geophysical monitoring (electrical resistivity and seismic refraction tomography) as well as acoustic, hydraulic and geotechnical observation of instability and hydro-mechanical forcing. We aim at developing a realistic model for snow cover and snow melt in steep bedrock (SNOWPACK) and a coupled model that reveals hydro-thermal and hydro-mechanical effects of snow melt infiltration in fractured bedrock (UDEC). Model results will be validated using thermal and mechanical observation in the snow cover, at the rock surface and in the rock subsurface (borehole). The sensitivity of the models to altered snow scenarios will provide a more holistic view on climate change impacts on potentially hazardous permafrost rock faces.