68th Canadian Geotechnical Conference and 7th Canadian Permafrost Conference

ACTIVE LAYER VARIABILITY AND CHANGE IN THE MACKENZIE VALLEY, NORTHWEST TERRITORIES

Session: Characterization of Permafrost State and Variability I / Caractérisation et variabilité du pergélisol I

Caroline Duchesne, Geological Survey of Canada, Natural Resources Canada (Canada)
Sharon Smith, Geological Survey of Canada, Natural Resources Canada (Canada)
Mark Ednie, Geological Survey of Canada, Natural Resources Canada (Canada)
Philip Bonnaventure, University of Lethbridge (Canada)

The Geological Survey of Canada has maintained an active layer monitoring network in the Mackenzie Valley, Northwest Territories since 1991. Active layer thickness exhibits a great deal of spatial and temporal variability particularly at tree dominated sites. Active layer thickness generally increased between 1991 and 1998 and then generally declined until about 2004. Since 2005 active layer thickness has generally increased reaching peak values in 2012, although still less than the 1998 peak. Although thicker active layers may result from higher summer air temperatures, warmer conditions during the preceding winter can also substantially contribute to active layer thickness.