Evaluating the environmental impacts of permafrost mega-disturbances along the Dempster Highway, NWT

Regions: Gwich'in Settlement Area

Tags: permafrost, landscape disturbance, slumping, environmental change, shrub

Principal Investigator: Kokelj, Steven V (23)
Licence Number: 15453
Organization: NWT Geoscience Office
Licenced Year(s): 2014 2013 2012 2011 2010
Issued: Apr 06, 2014
Project Team: Denis Lacelle (Researcher, Ottawa U), Brendan O'Neill (PhD student, Carleton University), Joseph Culp (Researcher, University of New Brunswick), Steve Kokelj (Researcher, NWT Geoscience Office), Krista Chin (Researcher, CIMP), Brianna Levenstein (MSc Student, University of New Brunswick), Trevor Lantz (Researcher, University of Victoria), Emily Cameron (MSc Student, University of Victoria)

Objective(s): To document the extent of ecological change in impacted stream basins draining the eastern slope of the Richardson Mountains and to determine the mechanisms of slump initiation and stabilization.

Project Description: The objective of this research project is to document the extent of ecological change in impacted stream basins draining the eastern slope of the Richardson Mountains and to determine the mechanisms of slump initiation and stabilization. This study will focus on the Stoney Creek catchment, which runs parallel to the Dempster Highway and empties into the Peel River at Fort McPherson, NT. The catchment contains several permafrost mega-disturbances, active quarries, historical seismic activities and a major highway. Consequently, in the long-term, this area will also provide an excellent case study of regional cumulative effects.

In 2014-2015 we also propose to examine the effects of shrub clearing on permafrost conditions along the Dempster Highway. Based on ecological observations it is evident that shrubs have proliferated on terrain adjacent to the Dempster Highway. The monitoring supported by the NWT Cumulative Impact Monitoring Program reveals that shrubs cause snow to accumulate, prevent heat loss from the ground in winter and cause the permafrost to thaw. The research team believes that shrub growth has been accelerated due to road dust and disturbance from the highway. Ground warming and permafrost thaw can compromise the road embankment.

To estimate the dates of slump initiation and rates of growth, this study will examine archived LANDSAT imagery and historical aerial photographs. Historical aerial photographs archived by the Aurora Research Institute (ARI) and the University of Victoria will be scanned and georeferenced. Combined with recent satellite images, these photos will be used to map natural and human disturbances between the late 1940s and early 1990s. The development and growth of the large disturbances can be tracked with coarser-scale LANDSAT imagery (1980-Present). Standard remote sensing techniques will be utilized. Air photos housed by ARI will be scanned and mapping will be initiated.

The impacts of the large permafrost disturbances will be evaluated by sampling both impacted and unimpacted tributaries and sites upstream and downstream of individual disturbances. The CABIN protocol for assessing aquatic health will be implemented at the selected sites. Water level and water quality recorders will also be deployed at several impacted and non-impacted sites.

Aquatic assessments will employ the Canadian Aquatic Biomonitoring Network (CABIN) protocol developed by Environment Canada (http://cabin.cciw.ca). This methodology has been peer reviewed and is used, nationally, by other federal departments (DFO, Parks Canada and Environment Canada) as well as the BC and Yukon Territory governments to determine the health of freshwater ecosystems in Canada.

Data loggers recording turbidity, dissolved oxygen, pH, temperature, depth and conductivity will be deployed in June and retrieved in September. Surface water samples will be collected three times throughout the field season; May, July and September. The samples collected in May and September will coincide with the deployment and retrieval of the data loggers. Additional water sampling is proposed to be conducted by community members where the creek (Stoney Creek) enters the Peel River. CABIN field data will be collected in late-July or early August and entered onto the national database in the fall. Field sites and data will be summarized and reported on to Cumulative Impacts Monitoring Program.

The historical frequency of large-scale disturbances in the streams draining the Richardson’s will be investigated using paleolimnological techniques. Researchers will obtain sediment cores from small lakes near the ends of the streams. The sediments in the lake bottom will likely provide an archive of large-scale changes in the catchment.

Permafrost and terrain information will be collected to examine the influence of permafrost disturbances on landscape evolution. Topographic surveys will be conducted to document the size of the disturbances and to estimate the volumes of sediments that are being contributed to the stream valleys. Soil and runoff samples from the disturbances will also be obtained to determine the chemical composition of the thawing permafrost which is entering the stream. This sampling will be conducted in late-July when the other field teams are conducting the CABIN sampling. Ground temperatures will be collected at sites across an elevation gradient to determine the thermal regime of permafrost in the region. Permafrost monitoring sites will be maintained so that changes in ground temperatures can be detected. All permafrost data will be collected following national standards and stored on the NT GoMap database housed at the Northwest Territories Geoscience Office.

Information pertaining to additional 2014 activities - shrub clearing along Dempster
In 2014 the research team will clear shrubs along 3 of the 5 study sections immediately adjacent to the highway. Brushing will occur on plots 2, 3 and 5. Plots 1 and 4 will serve as control areas. The research team have consulted with Department of Transportation (DOT) and have their full support for these activities. The sections will be 100 m in length and may extend up to 50 m away from the highway. The brushing will take place in late summer 2014 by handheld, powered equipment (not heavy equipment) to minimize disturbance of the terrain surface. Shallow thermistors will be installed to determine if the removal of shrubs will help cool the ground in winter by reducing snow accumulation. Snow surveys will be conducted in these areas in winter and active layer thickness will be assessed in summer. The rates of shrub regrowth will also be monitored. Results will be shared with the communities, Gwich’in Tribal Council and DOT as shrub control may provide a viable option to maintain permafrost along infrastructure corridors. Members of the Tetlit Gwich’in Renewable Resource Council (RRC) are involved in all aspects of fieldwork conducted by this project.

All fieldwork will involve teams consisting of scientific staff and local community researchers.

Community members will be involved in all aspects of the proposed fieldwork. They will be paired with researchers to stimulate exchange of knowledge on the environment. Local field assistants will be trained in established protocols, in particular with respect to evaluation of aquatic health (CABIN), water sampling and collection of permafrost data.

This project presents a substantial opportunity for local involvement in study design, field data collection and reporting. This project also affords several training opportunities that will enable community members to sustain the collection of relevant monitoring data after this initial study is completed.

In each of the past 4 years the project has provided between 50 and 80 days of community member employment. Numerous field workshops and field training sessions have been provided by the project team.

Fort McPherson community: The intent of the research team is to conduct research examining the impacts of large scale permafrost degradation on the watersheds draining the Richardson Mountain foothills has already been discussed with the Tetlit Gwich’in RRC. Prior to conducting field work the research team will consult with the Tetlit Gwich’in RRC to develop a study design. A related project recording Gwich’in perceptions of environmental change will also host a knowledge sharing workshop involving the participation of scientists involved in this project. Results from summer fieldwork will be shared with community members during a winter gathering in Fort McPherson. A poster and a 1-2 page plain language summary of the results will be developed.

Communication with the community of Fort McPherson has been ongoing through field oriented workshops, community meetings and reporting and annual regional RRC meetings. This practice will continue through the duration of the project.

The fieldwork for this study will be conducted from April 6, 2014 to December 31, 2014.