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TitreField investigations to characterize current ground thermal conditions in the Alaska Highway Corridor, Yukon Canada
AuteurSmith, S L; Lewkowicz, A G; Duguay, M; Ednie, M; Bevington, A
Source4th European Conference on Permafrost EUCOP4, book of abstracts; 2014 p. 37
Année2014
Séries alt.Secteur des sciences de la Terre, Contribution externe 20140035
ÉditeurInternational Permafrost Association
Réunion4th European Conference on Permafrost EUCOP4; Évora; PT; juin 18-21, 2014
Documentlivre
Lang.anglais
Mediapapier; en ligne; numérique
Formatspdf
ProvinceYukon
SNRC105D/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
Lat/Long OENS-141.0000 -134.0000 62.7500 60.7500
Sujetscongélation du sol; glace fossile; températures au sol; pergélisol; analyses thermiques; géologie des dépôts meubles/géomorphologie; géologie de l'ingénieur; Cénozoïque; Quaternaire
Programmeadaptation et impacts sur l'environnement, environnement du nord, Géosciences de l'environnement
LiensOnline - En ligne
Résumé(disponible en anglais seulement)
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.
Résumé(Résumé en langage clair et simple, non publié)
Des sites instrumentés établis en 2011-2013 le long du corridor de la route de l'Alaska entre Whitehorse et la frontière de l'Alaska permettent d'obtenir de nouvelles données sur les conditions actuelles de pergélisol. Ces données sont nécessaires pour effectuer un certain nombre d'évaluations de la vulnérabilité du terrain et planifier le développement du Nord (p. ex. construction de pipelines et de routes) afin d'assurer l'intégrité de l'infrastructure et de l'environnement. Les résultats montrent que le pergélisol dans la présente section du corridor est relativement chaud (températures au-dessus de -1,5 °C, mais pouvant atteindre jusqu'à -3 °C près de la frontière de l'Alaska). Si l'on compare avec les températures au sol mesurées à la fin des années 1970, les températures de pergélisol semblent avoir augmentées de 0,5 °C au cours des 30 dernières années. La perturbation du milieu semble également avoir donné lieu au réchauffement et au dégel du pergélisol.
GEOSCAN ID293912