NWT RESEARCH DATABASE

Regions: Sahtu Settlement Area

Tags: physical sciences, permafrost, climate change, groundwater

Objective(s): To conduct terrestrial geophysical surveys in selected regions in order to help calibrate and ground truth the airborne electromagnetic (AEM) data; to conduct detailed subsurface monitoring to develop a better understanding of the fate and transport of carbon species associated with the permafrost thawing processes.

Project Description: This licence has been issued for the scientific research application No. 5617. Within the Central Mackenzie Valley of the Northwest Territories (NWT), discontinuity and rapid change within the regional permafrost is anticipated to be influencing landscape, hydrology, habitat and ecosystem characteristics along with presenting challenges for the stability of constructed infrastructure. Mapping the nature and location of subsurface permafrost conditions is of interest for many applications and has proven to be both extremely challenging and costly, especially within a discontinuous permafrost environment. Recent surveys conducted with new airborne electromagnetic (AEM) survey methods within the field region of interest have proven promising in mapping permafrost occurrence and continuity on a regional scale. In addition, detailed hydrogeological investigations that have been completed within the Bogg Creek watershed near Norman Wells over the last decade have provided evidence of how permafrost influences groundwater flow and the movement of dissolved geochemical species, including carbon compounds such as methane and carbon dioxide, which are considered greenhouse gases. In order to enhance the capability of the AEM survey data to delineate permafrost occurrence and to improve the understanding of how groundwater flow dynamics influence the fate of subsurface carbon in discontinuous permafrost terrain, terrestrial geophysical surveys will be conducted in selected regions in order to help calibrate and ground truth the AEM data. In addition, detailed subsurface monitoring will be conducted to develop a better understanding of the fate and transport of carbon species associated with the permafrost thawing processes. The combined field studies will provide further insight into the role of groundwater in the changing hydrologic and ecologic conditions, along with wildlife habitat in the northern landscape and also contribute to understanding how the processes of permafrost thaw are influencing the release of carbon from the subsurface, which is widely regarded as a potential factor in enhancing climate warming. Based on the combined results of the previous hydrologic and ecologic investigations within the Bogg Creek watershed and the initial results of the AEM surveys, a series of four field sites will be chosen within the watershed for detailed follow-up field investigation. The sites will be chosen to encompass specific landform conditions and subsurface geological settings of interest relative to their influence on permafrost thaw rates. These will include sites along surface water bodies, near wetland areas, in artificial clearings including old seismic lines and in regions with thick organic soil profiles. At each site, groundwater and surface water samples will be collected using portable sampling techniques successfully utilized during previous field work within the Bogg Creek water shed, along with novel soil gas collection techniques that will employ simple, manual techniques modified from those used at petroleum contamination sites. The water and gas samples will be preserved and shipped to analytical laboratories in Edmonton and Ottawa. In addition to the water and gas sampling, continuous soil cores will be collected at each of the sites where intact permafrost is shallow and where significant thawing has already occurred to permit a comparison of the nature of the carbon content in the soils. The core samples will be preserved and shipped to an analytical laboratory facility at the University of Ottawa for detailed investigation. In addition to the subsurface monitoring, terrestrial geophysical surveys based on ground penetrating radar (GPR) and electrical resistivity tomography (ERT) techniques will be conducted over the selected field sites in order to develop more precise estimates of permafrost occurrence and continuity in the vicinity of the difference landscapes and also to provide information to inform the interpretation of the AEM survey data collect during the previous year’s field work. Data derived through the combined monitoring approaches will be used to further the understanding on how surface water features and landform characteristics influence the thaw rate of permafrost and control the release of carbon compounds trapped within the frozen subsurface environment. The research team will provide reports and plain language materials detailing the team’s progress and findings to interested parties. Researchers on the project have been active in the Ne K’? Dene Ts'i?li? Forum, which provides a regular opportunity for research updates to community members, government, and other scientists. Researchers on the project will meet annually with representatives from the Sahtú Renewable Resources Board, through the Norman Wells and Tulita Renewable Resources Council to discuss the research plans and research findings. In addition, the results of the research will be transferred to the Government of the Northwest Territories and Cenovus Energy through annual reports and presentations to collaborating groups. The fieldwork for this study will be conducted from July 20, 2023 to August 31, 2023.