Solifluction Processes in a Discontinuous Permafrost Arctic Landscape: Insights from Two Years of Dense Monitoring

Solifluction processes inherent in Arctic environments introduce a layer of complexity when estimating both current and future soil carbon dynamics and fluxes. This intricacy extends to the assessment of hillslope stability and infrastructure resilience. Understanding the dynamic interplay of factors in the Arctic landscape requires a meticulous examination of triggers and drivers behind soil movement in hillslopes with discontinuous permafrost. In this study, we made use of a novel dense monitoring approach to obtain vertically resolved, continuous observations of soil movement and temperature at tens of locations across multiple adjacent hillslopes throughout two successive thawing seasons to better understand the mechanisms at play.Results show substantial soil movements, with surface deformations reaching up to 344 mm in the second year. The upper parts of the watershed exhibited the greatest movements, with thaw depth, slope angle, and thermal conditions identified as key factors influencing solifluction. Thaw depth played a central role, triggering deformation by impacting water pressure at the thawing front. Soil temperature influenced both thawing and freezing processes, affecting soil cohesion and internal friction, which are critical for slope stability. A Factor of Safety proxy based on observed data has been developed and proved useful for assessing slope stability and understanding the effects of soil thermal conditions on deformation. This study provides new insights into the triggers of hillslope movements, contributing to the broader understanding of soil redistribution in Arctic environments and the implications for future landscape and infrastructure resilience in these regions.