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We studied processes of ice-wedge degradation and stabilization at three sites adjacent to road infrastructure in the Prudhoe Bay Oilfield, Alaska, USA. We examined climatic, environmental, and subsurface conditions and evaluated vulnerability of ice wedges to thermokarst in undisturbed and road-affected areas. Vulnerability of ice wedges strongly depends on the structure and thickness of soil layers above ice wedges, including the active, transient, and intermediate layers. In comparison with the undisturbed area, sites adjacent to the roads had smaller average thicknesses of the protective intermediate layer (4 cm vs. 9 cm), and this layer was absent above almost 60% of ice wedges (vs. ∼45% in undisturbed areas). Despite the strong influence of infrastructure, ice-wedge degradation is a reversible process. Deepening of troughs during ice-wedge degradation leads to a substantial increase in mean annual ground temperatures but not in thaw depths. Thus, stabilization of ice wedges in the areas of cold continuous permafrost can occur despite accumulation of snow and water in the troughs. Although thermokarst is usually more severe in flooded areas, higher plant productivity, more litter, and mineral material (including road dust) accumulating in the troughs contribute to formation of the intermediate layer, which protects ice wedges from further melting.
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Ice-wedge thermokarst: Past, present, and future
Ice-wedge thermokarst has played an important role in permafrost evolution, and numerous cycles of ice-wedge formation/degradation have occurred through the Quaternary history. Studies of ice-wedge degradation help to explain processes of past ice-wedge thermokarst and predict its future consequences. We developed a conceptual model of ice-wedge degradation/stabilization, which is based on the dynamics of the intermediate layer of the upper permafrost. This model explains high resilience of ice-wedge systems and low probability of formation of large thaw lakes in the continuous permafrost zone. Absence of the intermediate layer at the time of yedoma accumulation and increased precipitation caused very high activity of thaw-lake formation during the Pleistocene/Holocene transition.
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- Award ID(s):
- 1023623
- PAR ID:
- 10110430
- Date Published:
- Journal Name:
- 5th European Conference On Permafrost – Book of Abstracts, 23 June – 1 July 2018, Chamonix, France
- Page Range / eLocation ID:
- 647-649
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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