Thermokarst distribution and susceptibility in Yukon: lakes, landslides and pingos

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Kienzle, Oliver K.
University of Lethbridge. Faculty of Arts and Science
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Lethbridge, Alta. : University of Lethbridge, Dept. of Geography and Environment
The most tangible consequence of permafrost thaw is thermokarst, which is landscape destabilization resulting from ground ice melt. The main objective of this thesis was to model and map thermokarst susceptibility across Yukon, Canada. An inventory of 3376 historically mapped thermokarst landform point locations was extracted from the Yukon Geological Survey’s Digital Surficial Geology dataset. Of these, 25 lakes, 27 landslides and 93 pingos in the Dawson City study area were manually delineated on the World Imagery baselayer in order to assess their morphology and distribution relative to similar landforms in other regions. Subsequently, generalized linear models of thermokarst susceptibility in Yukon were constructed using a range of topographic, geologic, environmental and climatic predictor variables from existing regional or global datasets. A novel potential surface radiation adjustment was developed to correct for seasonal snow cover. Using the mapped thermokarst landforms in the Dawson City study area as a training dataset set, the resulting optimal lake and landslide susceptibility models use slope as the sole predictor variable, while the pingo susceptibility model uses profile curvature. Overall, 3, 34 and 0.1 % of Yukon is modelled as being highly susceptible to thermokarst lake, landslide and pingo development, respectively. The models were evaluated using the Yukon thermokarst point location dataset, randomly distributed points, and select multivariate logistic models. The thermokarst lake susceptibility model performed best overall. This study shows that relatively simple modelling techniques can be effective in mapping thermokarst susceptibility, and highlights the importance of rigorous, up-to-date thermokarst landform inventories to aid in future modelling efforts.
Thermokarst distribution , Thermokarst susceptibility , Permafrost thaw , Lakes , Landslides , Pingos , Dawson City study area