Making Buildings and Roads Safer in Canada's North
By Terence Martin
March 2011
larger image
After a long day of work, team members enjoy some well-deserved rest as they watch the sun set in Sylvia Grinnell Territorial Park, Iqaluit.
A team of Natural Resource Canada (NRCan) scientists, working under the Climate Change Geoscience program, and researchers from the Université Laval's Centre d'études nordiques recently completed a detailed field study of how permafrost conditions in Iqaluit, Nunavut are changing. Their results will have two important applications: identifying potential threats to existing structures and locating the safest places for roads, buildings and other construction projects. These results are particularly relevant in light of a changing climate and its impact on northern infrastructure.
Officials from Iqaluit are well aware of the importance of this kind of research after the 2008 flooding in Pangnirtung, 300 km north of their community. The flooding was caused by heavy rain falling on snow, producing rapid runoff that degraded the permafrost contained within the banks of rivers and streams. The bridge in Pangnirtung was washed out, and the community was cut off from its water supply, sewage facilities, municipal dump and sand and gravel pit.
Permafrost Affected by Climate Change and Human Activities
larger image
Anne-Marie conducts a ground penetrating radar survey on a foggy day in Iqaluit. The study site is also equipped with a thermistor cable to measure ground temperatures (black tube in foreground).
Permafrost is either soil or rock that remains below the freezing point of water year-round. Its stability can be affected by changes in various local thermal conditions, such as snow cover and warmer climates, or through the construction of infrastructure such as roads, buildings and pipelines.
The impacts of changes in the climate depend on the temperature of the permafrost and the proportion and position of ice within it. “If you build on bedrock and the climate warms up, the ground still stays pretty stable,” says Anne-Marie LeBlanc, a permafrost scientist with NRCan’s Geological Survey of Canada (GSC). “But if we’re looking at clay and ice in the ground, warming can result in changes in the behaviour of the ground.”
Getting the Ground to Give Up Its Secrets
The research group split into several teams to do their work. University team members conducted shallow drilling to extract permafrost cores, while the NRCan teams looked into the ground using two non-invasive geophysical methods.
The research group also analyzed aerial photos to determine whether the ground is made up of clay, sand or rock and to learn how it was deposited there. They also inserted cables into the ground to measure and record changes in ground temperature over the course of a year.
Research Products
larger image
A permafrost core from an ice-rich layer. Dark lenses are made of ice surrounded by sand and gravel particles.
The permafrost and climate data will be entered into a database to create a digital map showing the surface topography of the area and the permafrost conditions. City planners and the Government of Nunavut will then use this information to prepare permafrost sensitivity maps when designing infrastructure and making land-use decisions.
The research results will also serve other purposes. “The data we’re collecting will be useful to the individual communities, but will also contribute to long-term studies that can apply across the territory,” says David Mate, project leader with NRCan’s Geological Survey of Canada.
To learn more about how NRCan is helping to build climate change planning capacity in the region, read our July 2010 article, “Partnership Helps Nunavut Communities Adapt to Climate Change.”
To read about related articles, see Climate Change
For information on reproducing articles, please see our non commercial reproduction section.