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TitleLong-term permafrost degradation and thermokarst subsidence in the Mackenzie Delta area indicated by thaw tube measurements
AuthorO'Neill, H B; Smith, S L; Duchesne, C
SourceCold Regions Engineering 2019: proceedings of the 18th International Conference on Cold Regions Engineering and the 8th Canadian Permafrost Conference; by Bilodeau, J -P (ed.); Nadeau, D F (ed.); Fortier, D (ed.); Conciatori, D (ed.); 2019 p. 643-651, https://doi.org/10.1061/9780784482599.074
Year2019
Alt SeriesNatural Resources Canada, Contribution Series 20180401
PublisherAmerican Society of Civil Engineers
Meeting18th International Conference on Cold Regions Engineering and 8th Canadian Permafrost Conference; Québec, QC; CA; August 18-22, 2019
Documentbook
Lang.English
Mediaon-line; digital
File formatpdf (Adobe® Reader®)
ProvinceNorthwest Territories
NTS107B/02; 107B/03; 107B/06; 107B/07; 107B/10; 107B/11; 107B/14; 107B/15; 107C/02; 107C/03; 107C/06; 107C/07; 107C/10; 107C/11
AreaMackenzie Delta; Richards Island; Kittigazuit Low Hills; Tununuk Low Hills; Mackenzie River; Inuvik; Caribou Hills; Inuvik to Tuktoyaktuk Highway; Canadian Arctic
Lat/Long WENS-135.0000 -133.0000 69.7500 68.0000
Subjectssurficial geology/geomorphology; environmental geology; Nature and Environment; Science and Technology; permafrost; ground ice; periglacial features; thermokarst; subsidence; in-field instrumentation; climate; statistical analyses; sediments; glacial deposits; glacial landforms; glacial features; moraines; kames; coastal environment; terraces; deltas; Anderson Plain; climate change; permafrost degradation; permafrost thaw; thaw tubes; elevations; active-layer thickness; site characteristics; glaciofluvial sediments; alluvial sediments
Illustrationslocation maps; tables; geoscientific sketch maps; time series; plots
ProgramClimate Change Geoscience, Permafrost
ProgramPolar Continental Shelf Program
Released2019 08 08
AbstractLong-term measurements (1991-2016) from 17 thaw tubes in the Mackenzie Delta region were analyzed to investigate changes in thaw penetration (TP), ground surface (GS) elevation relative to a stable benchmark, and active-layer thickness (ALT). TP increased significantly during the study period at 10 of the sites, at a median rate of 0.5 cm/a (min: 0.2, max: 1.5 cm/a). Significant subsidence occurred at 10 sites, at a median rate of 0.4 cm/a (min: 0.2, max: 0.8 cm/a). These results indicate long-term regional permafrost degradation and surface subsidence in the western Canadian Arctic. About 5 to 38 cm of permafrost have thawed over 25 years at the sites, and ~5 to 20 cm of excess ground ice have melted. ALT increased significantly at only 5 of the sites and decreased at 4 sites. In ice-rich ground, increases in TP can more than double increases in ALT. For example, at a site near Inuvik, ALT increased by only 19 cm between 1994 and 2016, but TP increased by about 40 cm and was accompanied by 20 cm of surface subsidence. At sites in ice-poor ground, negligible settlement occurs, and increases in TP and ALT are similar. In ice-rich terrain, the degradation of permafrost cannot be detected by probing for active-layer thickness alone.
Summary(Plain Language Summary, not published)
Long-term measurements (1991-2016) from 17 thaw tubes in the Mackenzie Delta region of Canada's western Arctic were analyzed to investigate changes in thaw penetration into permafrost and ground surface elevation relative to a stable benchmark, to determine rates of permafrost degradation and ground surface subsidence associated with recent climate warming. Overall, there was systematic regional permafrost degradation, at rates of up to 1.5 cm per year. Significant ground surface subsidence occurred at sites with ice-rich permafrost, at a maximum rate of 0.8 cm per year. These results indicate long-term regional permafrost degradation and surface subsidence in the western Canadian Arctic. About 5 to 38 cm of permafrost have thawed over 25 years at the sites, and about 5 to 20 cm of excess ground ice have melted.
GEOSCAN ID313661