Report on 2010-11 permafrost investigations in the Yellowknife area, Northwest Territories

Abstract

This open file reports on recent geoscience data collected and monitoring sites installed by the Geological Survey of Canada (GSC) in collaboration with Aboriginal Affairs and Northern Development Canada (AANDC), Northwest Territories Geoscience Office (NTGO), Government of the Northwest Territories (GNWT) Environment and Natural Resources (ENR) and the Department of Transport (DOT), BGC Engineering Inc., Carleton University, and the University of Ottawa. The report represents the first of several co-published GSC / NTGO Open File reports under the Climate Change Geoscience Program. A 2010-11 field program under the Transportation Risk in the Arctic to Climatic Sensitivity (TRACS) activity in the Climate Change Geoscience Program included extensive fieldwork in the Yellowknife area between June and September, 2010. Field data collection by the Geological Survey of Canada and Carleton University included 14 CRREL-cored boreholes and ecological descriptions at 48 sites. An additional 20 ecological site descriptions were made by University of Ottawa students. Collaborative work with BGC Engineering Inc. included field observations and soil analysis (grain size and Atterberg limits) at test pits along Highway 3, and 15 water-jet drilled holes for subsequent temperature cable installations. Numerous temperature measurement sites were also established with AANDC along a 170 km transect between Behchoko and Tibbitt Lake including six air temperature sites, six multi-channel near-surface temperature sites and seven water temperature sites. In March 2011, additional field data were collected including snow depths at 45 sites, densities at 18 sites, and ice thicknesses at eight pond sites. Snow depth transect surveys were also conducted at 11 sites along Highway 3, across the highway embankments and right-of-ways. These data were collected in order to provide baseline information regarding the nature and properties of permafrost in the Yellowknife area.

The Occurrence and Thermal Disequilibrium State of Permafrost in Forest Ecotopes of the Great Slave Region, Northwest Territories, Canada

“…Gravimetric moisture, organic‐layer thickness, depth to the top of permafrost and depth to bedrock (where contacted) determined from borehole data for (a) white birch forest (WB), (b) black spruce forest (BS) and (c) peatlands (PL) (includes data from Wolfe et al ., , Figure 11).…”

“…The lithalsas are up to 8 m high and several hundred metres long and wide, and are vegetated by white birch forest and mixed forest; they represent thaw-sensitive terrain. Permafrost likely also exists beneath black spruce forests (Wolfe et al, 2011).…”

“…The majority of vegetative ecotopes are forests that may be black spruce ( Picea mariana ) dominated (Figure c), mixed deciduous and coniferous forests, or pure stands of white birch ( Betula papyrifera ) (Figure d) (Olthof et al ., ). Recent geotechnical drilling and electrical resistivity surveys show that ice‐rich sediments are common beneath black spruce and white birch forests to depths exceeding 8 m (Wolfe et al ., , ). Permafrost may therefore be more widespread than presently understood, occurring in unconsolidated fine‐grained sediments.…”

Spatiotemporal impacts of wildfire and climate warming on permafrost across a subarctic region, Canada

“…We used the same distribution parameters as described by Zhang et al [2014] as this study area overlaps with the previous one. Based on borehole observations [Wolfe et al, 2011], the depths of surficial deposits (including peat and mineral soils above bedrock) are assumed to be 0.05 m with 98% gravel content for bedrock outcrops, 2 to 3 m for low vegetation or barren lands (depends on the surface organic layer thickness), 7 m for bogs and fens, and 5 m for other land cover types.…”

Icings near the Tibbitt to Contwoyto Winter Road, Great Slave Uplands, Northwest Territories

“…The average snow density at the three southern sites was slightly higher in 2013/14 than in 2012/13, while at P23, the average snow density was similar in both years (0.13 g cm -3 ). Overall snow densities were low when compared to other measurements in the region (e.g., Karunaratne 2011, Wolfe et al 2011. This may be due to the timing of the snow density measurements being one to two months earlier in this study than in the cited works (Karunaratne 2011, Wolfe et al 2011, as increased snow densification would be expected with time.…”