Use of Direct Current (DC) Resistivity Profiling To Investigate Thin Permafrost in the Alaska Highway Corridor Christina Miceli MSc Candidate Supervisor: Antoni Lewkowicz University of Ottawa

Permafrost Ground that remains below 0°C for a minimum of 2 years Discontinuous Thin and occupies only parts of the landscape Susceptible to thaw Permafrost has disappeared at half the sites where it was found in a 1964 survey (NRCAN, 1975) Continuous Widespread Discontinuous Sporadic Discontinuous

Research Sites Ten research sites along 1200 km of the Alaska Highway Whitehorse, Yukon to near Fort St. John, B.C.

Methods Set up ground temperature, air temperature, snow monitoring at each site 20 m

Methods Direct Current (DC) Resistivity Profiling - Electrical current (from a car battery) passed into the ground through a line of electrodes to map out an area’s resistivity -Resistivity differs greatly between frozen and thawed soil because water is a good conductor of electrical energy and ice is a poor conductor

Results Resistivity profiles show thin permafrost at almost all of the sites. Permafrost Unfrozen Threshold is at around 300 ohm-metres 4-10 m thick permafrost

Unfrozen Permafrost Little evidence of permafrost at the surface of some sites even though the resistivity profiles show it is present Threshold is at around 300 ohm-metres 4 m thick permafrost

Research Significance Unique experiment for thin permafrost Little knowledge of freeze-thaw cycles Allows for – Short term/Seasonal monitoring – Long term/Climate monitoring Help to predict and better understand – Problems with infrastructure over thin permafrost – Geohazards – Hydrological and ecological change

Future Work Additional Surveys in Winter, Summer, and Fall 2011 Results will tell us about the dynamics of thin permafrost in relation to climate and climate change

Acknowledgments Royal Canadian Geographical Society Royal Bank of Canada’s Blue Water Project NSERC, University of Ottawa, Natural Resources Canada Max Duguay