ABSTRACT: Permafrost changes along the Alaska Highway Corridor, southern Yukon, from ground temperature measurements and DC electrical resistivity tomography.

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Abstract

A natural gas pipeline running across permafrost terrain from Prudhoe Bay, Alaska, through Canada to US markets was first proposed more than 30 years ago. In the intervening period, mean annual air temperatures in the region have risen by 0.5-1.0°C and it is probable that the ground has also warmed. Renewed interest in the pipeline has meant that information on permafrost and geotechnical conditions within the Alaska Highway Corridor of the southern Yukon must be updated for engineering design and the assessment of environmental impacts. To accomplish this goal, results from 1977-1981 drilling and ground temperature monitoring programs within the proposed pipeline corridor were used in combination with air photo analysis to select sites potentially sensitive to climate change. The sites are distributed across the extensive and sporadic discontinuous permafrost zones over a distance of 475 km between Beaver Creek and Whitehorse. To date, 11 targeted boreholes with permafrost have been found and cased to permit renewed ground temperature monitoring. By the end of summer 2011, it is expected that another 7 will have been instrumented. Measurable temperature increases relative to the 1970s are expected, except where values were previously just below 0°C. In the latter case, if the sites are still in permafrost, latent heat effects may have substantially moderated the temperature increase. Electrical resistivity tomography surveys are also being conducted to characterize the local permafrost distribution and geotechnical conditions. These 2D resistivity profiles will be used with the ground temperatures to examine current conditions and response to climate change and vegetation disturbance.

Bibliography of Canadian Geomorphology