|Title||Field investigations to characterize current ground thermal conditions in the Alaska Highway Corridor, Yukon Canada|
|Author||Smith, S L; Lewkowicz, A G; Duguay, M; Ednie, M; Bevington, A|
|Source||4th European Conference on Permafrost EUCOP4, book of abstracts; 2014 p. 37|
|Links||Online - En ligne|
|Alt Series||Earth Sciences Sector, Contribution Series 20140035|
|Publisher||International Permafrost Association|
|Meeting||4th European Conference on Permafrost EUCOP4; Évora; PT; June 18-21, 2014|
|Media||paper; on-line; digital|
|NTS||105D/13; 105D/14; 115A/13; 115A/14; 115A/15; 115A/16; 115B/16; 115F/15; 115F/16; 115G/01; 115G/02; 115G/05; 115G/06; 115G/07; 115G/11; 115G/12; 115G/13; 115K/02; 115K/07; 115K/10|
|Area||Alaska Highway Corridor|
|Lat/Long WENS||-141.0000 -134.0000 62.7500 60.7500|
|Subjects||surficial geology/geomorphology; engineering geology; freezing ground; ground ice; ground temperatures; permafrost; thermal analyses; Cenozoic; Quaternary|
|Program||environmental impacts and adaptation in the northern environment, Environmental Geoscience|
|Abstract||The Alaska Highway corridor traverses the discontinuous permafrost zone of the southern Yukon. Although a significant amount of information on permafrost conditions was collected over 30 years ago to
support a previous pipeline proposal, little recent information on ground thermal conditions existed. Air temperatures in the region have increased 0.4-0.5°C per decade since the 1970s and recent studies in the corridor indicate that warming and
thawing of permafrost has occurred over the last 3-4 decades (e.g. James et al. 2013). Recent proposals for construction and operation of a natural gas pipeline and the need to develop climate change adaptation strategies for existing highway
infrastructure has stimulated the need for updated information on current permafrost conditions.|
The Geological Survey of Canada measured ground temperatures in the corridor in 17 boreholes between 1978 and 1981 (Burgess et al. 1982). In summer
2011, eleven of these boreholes between Whitehorse and the Alaska border were instrumented for ground temperature measurement to depths of up to 8.5 m. Ground temperature records of up to two years in length have been acquired from these boreholes.
Eight boreholes (up to 10 m deep) drilled along the highway easement in 2011, were instrumented in summer 2013. Electrical Resistivity Tomography (ERT) surveys have also been conducted at many of the borehole sites to better describe the vertical and
lateral extent of frozen ground.
The ground thermal data collected since 2011 indicates that permafrost is generally warm (above -1.5°C) in the section of the corridor between Whitehorse and the Alaska border. However, colder permafrost (-3°C) was
found near the Alaska border. Results from ERT surveys indicate that permafrost thickness varies from less than 25 m near Kluane Lake to greater than 60 m near the Alaska border.
Comparison of recent temperature measurements with those made
1978-1981, indicates that permafrost persists at sites where it was present three decades ago. However, our analysis indicates ground temperatures at the depth of zero annual amplitude may have increased by more than 0.5°C since the late 1970s.
Increasing air temperatures are partially responsible for the observed ground warming. Environmental disturbance related to clearance of vegetation at some sites has also resulted in ground warming and increased thaw depths. Additional modelling
studies are planned to facilitate the attribution of the apparent ground warming in the corridor.
|Summary||(Plain Language Summary, not published)|
Instrumented field sites established 2011-13 along the Alaska Highway corridor between Whitehorse and the Alaska border, provide new information on
current permafrost conditions. This information is required for terrain sensitivity assessments and planning northern development (eg. pipeline, highway) to ensure infrastructure and environmental integrity. Results indicated that permafrost in this
section of the corridor is generally warm (temperatures above -1.5°C but is as cold as -3°C near the Alaska border. Comparison with ground temperatures measured in the late 1970s indicates that permafrost temperatures may have increased by 0.5°C over
the last 30 years. Environmental disturbance also appears to have resulted in warming and thawing of permafrost.