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Abstract Massive ground ice in Arctic regions underlain using continuous permafrost influences hydrologic processes, leading to ground subsidence and the release of carbon dioxide and methane into the atmosphere. The relation of massive ground ice such as ice wedges to water tracks and seasonally saturated hydrologic pathways remains uncertain. Here, we examine the location of ice wedges along a water track on the North Slope of Alaska using Ground‐Penetrating Radar (GPR) surveys, in situ measurements, soil cores, and forward modeling. Of nine unique GPR surveys collected in the summers of 2022 and 2023, seven exhibit distinctive “X”‐shaped reflections above columnar reflectors that are spatially correlated with water track margins. Forward modeling of plausible geometries suggests that ice wedges produce reflection patterns most similar to the reflections observed in our GPR profiles. Additionally, a large magnitude (∼71 mm) rain event on 8 July 2023 led to a ground collapse that exposed four ice wedges on the margin of the studied water track, ∼100 m downstream of our GPR surveys. Together, this suggests that GPR is a viable method for identifying the location of ice wedges as air temperatures in the Arctic continue to increase, we expect that ice wedges may thaw, destabilizing water tracks and causing ground collapse and expansion of thermo‐erosional gullies. This ground collapse will increase greenhouse gas emissions and threaten the Arctic infrastructure. Future geophysical analysis of upland Arctic hillslopes should include additional water tracks to better characterize potential heterogeneity in permafrost vulnerability across the warming Arctic.
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This content will become publicly available on September 1, 2026
Near‐Surface Drying of a Continuous Permafrost Hillslope With Water Tracks Following Ground Collapse
Increasing air temperatures in the Arctic cause permafrost to thaw, releasing carbon dioxide and methane into the atmosphere. Carbon in thawing permafrost is released approximately three times more readily when soils are unsaturated versus saturated. Therefore, understanding if the Arctic is wetting or drying as permafrost thaws is crucial to predicting soil carbon emissions. In upland permafrost regions, near‐surface soil moisture is influenced by unchannelized curvilinear zones of enhanced saturation known as water tracks. The ground underneath water tracks can collapse into thermoerosional gullies, altering their thaw depth and seasonal saturation. Water tracks and thermoerosional gullies frequently occur together on upland hillslopes but exhibit heterogeneous saturation dynamics. Thus, understanding saturation states in water tracks and gullies is crucial to predicting soil carbon emissions. In this study, we quantify saturation across water tracks and a gully and examine changes in near‐surface saturation metrics over time by leveraging ~30 years of meteorological data and remotely sensed wetness indices from Landsat (1994–2023) and PlanetScope (2017–2023) imagery for a permafrost hillslope on the North Slope of Alaska, USA. Results suggest that the studied water tracks are drying following the ground collapse event, decreasing the overall saturated area proximal to the collapse, but that the water tracks still have relatively high mean Normalised Difference Water Index (NDWI) values for all rainfall magnitudes. Given the importance of soil saturation for predicting carbon emissions, the results of this work may provide tools for improving estimates of carbon release from thawing continuous permafrost hillslopes.
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- PAR ID:
- 10653227
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Hydrological Processes
- Volume:
- 39
- Issue:
- 9
- ISSN:
- 0885-6087
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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