Retrogressive thaw slumps on ice-rich permafrost under degradation: Results from a large-scale laboratory simulation

International audienceIn the ice-rich permafrost of the Arctic regions, thermokarst erosion on slopes induces the formation of large-scale retrogressive thaw slumps (RTS). They have significant geomorphological, hydrological and biogeochemical impacts on the landscape. Further research is thus needed to better understand the respective effect of ice content and permafrost heterogeneities on the dynamics of these erosional features. Here we present results of a full-scale physical modelling of RTS development in a cold room. The experimental setup was designed to simulate and compare two ground-ice settings (ice wedges, icy layers) with the thawing of icepoor permafrost (i.e.,reference model). Our results show that the melting of the icy layers induces a loss of decohesion of the overlapping frozen soil. The heterogeneous frozen soil with ice wedges needs a longer time until degradation, but undergoes a stronger and faster decohesion of its structure during the thawing phase