NWT RESEARCH DATABASE

Regions: North Slave Region

Tags: physical sciences, geology, permafrost, climate change, discontinuous permafrost, infrastructure planning

Objective(s): To describe and predict the occurrence of discontinuous permafrost in the northern Great Slave Lake region to assist in planning, development and maintenance of community and industry infrastructure.

Project Description: This activity will describe and predict the occurrence of discontinuous permafrost in the northern Great Slave Lake region to assist in planning, development and maintenance of community and industry infrastructure. Future changes in climate will affect permafrost distribution, temperatures and geotechnical conditions. It is anticipated that different landscapes across the region will exhibit varying responses to warming. This study will collect ground temperature and environmental information to describe the state of permafrost in the area. Supporting data from climatic, soils, vegetation, lakes and hydrological surveys will also assist in characterizing permafrost distribution. A broad objective is to characterize, model and predict permafrost occurrence under varying terrain types. Investigations will examine permafrost conditions across environmental transitions at a scale relevant to community and industry infrastructure planning. Sites will be selected to characterize the range of permafrost conditions. Local site conditions will be selected to capture variation in ground temperature conditions across transitions from thick unconsolidated deposits to bedrock, and with proximity to water bodies. Interested parties will be consulted to ensure sites will yield the most locally relevant data. Study design will involve instrumentation of thermistors at undisturbed locations within a designated unit, then placing additional thermistors with proximity to adjacent lakes, and along transitions of thinning overburden towards adjacent bedrock outcrops. Near-surface thermistors will be instrumented to describe active-layer conditions and freezeback characteristics of respective sites. Bedrock sites will be instrumented opportunistically where exploration or geotechnical investigations are or have taken place. Active layer thicknesses will be measured at each site. Active layer and near-surface permafrost samples will be obtained for each of the terrain units (with exception of bedrock) to depths of up to 3 m using a 5 cm diameter Cold Regions Research and Engineering Laboratory (CRREL) core barrel. Core samples will be analyzed for geotechnical and geochemical properties at Taiga Environmental Laboratory (INAC) in Yellowknife. Surficial geological and ecological data will be collected to describe site conditions. Vegetation description will include species and height, ground cover and organic matter thickness if applicable. Near surface soil samples will describe moisture conditions. Seasonal snow accumulation will be measured. Ground temperatures across transitions will be analyzed along with supplementary data on site conditions so that factors controlling local scale variability in temperature characteristics and sensitivities to thawing can be determined. Ground ice conditions will also be described for the respective terrain units and relations between ice content and environmental variables assessed. An assessment of ground ice volumes in the upper 3 m will be made. Models will be developed to explain variabilities in temperature and ground ice distributions with a goal towards mapping permafrost distribution and ground thermal conditions, ground ice distribution based on classification of remotely sensed imagery and terrain sensitivity. The project will work with communities through the Cumulative Impact Monitoring Program (CIMP) to implement a community-based monitoring program with a focus on protocols for monitoring climate, soils, vegetation, hydrology and permafrost. The proposed collaborative project will be supported by the Cumulative Impact Monitoring Program, which has a mandate of working with northern partners, in particular, communities to establish community focused monitoring programs. A component of the proposed work will involve training for local Aboriginal communities in the collection of environmental information. There will also be training opportunities for northern youth through building a stronger link with the Natural Resources Training Program and Environmental Monitor Training Program (Aurora College). The project will result in employment opportunities for community members. The results of this work will be communicated to NWT communities through workshops organized through the Cumulative Impact Monitoring Program. The research will also be communicated to groups and agencies responsible for managing infrastructure and regulating land and water use. This will be accomplished through venues such as the NWT Board Forum. Public lectures will also be provided. Training opportunities with local schools and Aurora College will also facilitate knowledge transfer to NWT residents. The fieldwork for this study will be conducted from February 28, 2013 to September 15, 2013.