Allometric scaling of retrogressive thaw slumps

• Main Authors: Sluijs, Jurjen, Kokelj, Steven V., Tunnicliffe, Jon F.
• Format: Text
• Language: English
• Published: 2022
• Subjects: Arctic; Canada; Tuktoyaktuk; Ice; permafrost; Thermokarst
• Online Access: https://doi.org/10.5194/tc-2022-149; https://tc.copernicus.org/preprints/tc-2022-149/

In the warming Arctic, retrogressive thaw slumping (RTS) has emerged as the primary thermokarst modifier of ice-rich permafrost slopes, raising urgency to investigate the distribution and intensification of disturbances and to determine trajectories of landscape evolution and the cascade of effects. Tracking RTS is challenging due to constraints of remote sensing products and a narrow understanding of thaw-driven landforms, however, high-resolution elevation models provide new insights into geomorphic change. Structural traits, such as RTS depth-of-thaw or volume, can be obtained through allometric scaling. To address fundamental knowledge gaps related to area-volume scaling of RTS, a suitable surface interpolation technique was first needed to model pre-disturbance topography upon which volume estimates could be based. Among 8 methods with 32 parameterizations, Natural Neighbour surface interpolation achieved the best precision in reconstructing pre-disturbed slope topography (90 th percentile Root Mean Square Difference ± 1.0 m). An inverse association between RTS volume and relative volumetric error was observed, with uncertainties <10 % for large slumps and <20 % for small-to-medium slumps. Second, a Multisource Slump Inventory (MSI) for two study areas in the Beaufort Delta (Canada) was required to characterize the diverse range of disturbance morphologies and activity levels, which provided temporally consistent information on thaw slump affected slopes and attributes. The MSI delineation of three high-resolution hillshade DEMs (airborne stereo-imagery, LiDAR, ArcticDEM) revealed temporal and spatial trends in these multi-year, chronic mass-wasting features. For example, in the Tuktoyaktuk Coastal Plains, a +38 % increase in active RTS and +69 % increase in total active surface area were observed between 2004 and 2016. However, the total area of RTS did not change considerably (+3.5 %) because the vast majority of active thaw slumping processes have occurred in association with past disturbances. ...