NWT RESEARCH DATABASE

Regions: Dehcho Region

Tags: physical sciences, landscape disturbance, permafrost degradation, land use management, surficial stability, seismic line

Objective(s): To test whether seismic lines can be constructed and managed to minimize permafrost loss.

Project Description: In discontinuous permafrost of the southern NWT, cleared transportation corridors, such as seismic lines, have recently been associated with permafrost loss, increased soil moisture and vegetation changes. Permafrost loss can lead to ground subsidence, infrastructure instability and the release of stored carbon into the atmosphere. The research team will test whether seismic lines can be constructed and managed to minimize permafrost loss. Specifically, are decreased line widths, line orientation, or increased ground-ice content related to permafrost resilience along seismic lines? The team will also test if permafrost has re-aggraded along seismic lines where forest cover is re-established. Study sites will be located on the Liard and Mackenzie Highways near the communities of Fort Simpson and Jean Marie River. Transects will be located on seismic lines of different ages, widths and orientations based on a review of literature and available imagery. Shallow and deep ground temperatures, ground ice content, soil moisture, and vegetation and snow characteristics will be measured. To test the hypotheses, the team plans to establish about ten 50 m transects across historic seismic lines and into adjacent undisturbed terrain. Deep (10 m) and shallow (1 m) ground temperature cables will be installed using water-jet drilling, core drilling or hand auguring; collect soil core samples for ground ice measurement using a core drill; install soil moisture probes by excavating and refilling soil pits; measure active-layer depths with a metal probe; and conduct vegetation surveys of the canopy, shrub and ground vegetation layers. Ground temperatures will be stored by dataloggers attached to the ground temperature cables and downloaded annually. Soil core samples will be analyzed in a laboratory to determine ground ice content. In the winter, snow surveys will be conducted along the transects to measure snow depth, density, and ground hardness. Before finalizing the study design and beginning data collection, the team would like to meet with community members from Fort Simpson and Jean Marie River to discuss the project and potential sampling locations. The research team is always happy to provide talks and discuss the work with community members during field visits. The research team plans to make data and results accessible to local communities in a variety of ways, including meetings with community members, presentations at northern-relevant conferences, such as the Yellowknife Geoscience Forum, and contribution to northern environmental guidance documents. The fieldwork for this study will be conducted from February 26, 2012 to August 31, 2012.