Avalanches in Canada: Understanding and mitigating the risks

 

Editor's note - With an increase in winter backcountry use, how do we help to reduce the risk of avalanche fatalities?

This article by Pascal Haegeli (NSERC Industrial Research Chair in Avalanche Risk Management, School for Resource and Environmental Management, Simon Fraser University) reviews our current knowledge base on avalanches and the blending of social sciences to help develop models for risk management. It first appeared in the ACC's 2018 State of the Mountains Report.

We'll continue to publish articles exploring the science of the current state of Canada's alpine on our blog throughout the year. Find them all here.


Avalanche incidents common across Canada

Snow avalanches are a serious mountain hazard in Canada. Between 1980 and 2016, 428 people died in Canada in 301 avalanche accidents. This is roughly twice the number of fatalities from any other single meteorological or geological natural hazard (Fig. 1 & 2).

While most of these fatalities occurred in western Canada (British Columbia: 72%; Alberta: 20%; Yukon: 2%), fatal avalanche accidents also happened in Quebec, Newfoundland and Labrador and Nunavut. Apart from one fatality at an outdoor worksite, all avalanche fatalities during the last decade were winter backcountry recreationaists either making their own decisions (92%) or professionally guided (8%).

Among the self-directed recreational fatalities, 48% were mountain snowmobile riders, 31% backcountry skiers, 5% out-of-bounds skiers and 16% pursued other winter backcountry activities. In addition, avalanches affect important Canadian industries (e.g., forestry, mining, hydroelectric generation) and critical infrastructure (e.g., transportation corridors, transmission lines, pipelines). Every winter, the threat from avalanches causes traffic hazards and substantial economic loss through temporary closures of highways, railways and resource roads.

Figure 1 : Annual number of fatal avalanche accidents (blue dots with dashed line) and avalanche fatalities (red dots with solid line) in Canada from winters 1981 to 2017 (Avalanche Canada, (nd). Horizontal lines indicate ten-year averages of annual accident (blue dashed) and fatality (red solid) numbers.

Figure 1: Annual number of fatal avalanche accidents (blue dots with dashed line) and avalanche fatalities (red dots with solid line) in Canada from winters 1981 to 2017 (Avalanche Canada, (nd). Horizontal lines indicate ten-year averages of annual accident (blue dashed) and fatality (red solid) numbers.

Mitigating the risk

The risk from avalanches is managed through a combination of avalanche safety planning and operational programs. Avalanche safety planning identifies general exposure to avalanche hazard and designs solutions to either eliminate the risk (e.g., avoidance through land use regulation), or reduce the risk to an acceptable level.

Risk reduction may take the form of engineering solutions (e.g., snow nets, deflection dams, avalanche sheds) and/or operational avalanche safety programs. These programs manage avalanche risk in real-time by continuously monitoring conditions and choosing short-term mitigation measures (e.g., temporary closures, artificially triggering avalanches) to meet organizational objectives, such as keeping a road open, securing a ski run at a resort, or choosing safe backcountry terrain for guests.

To provide private recreationists with avalanche safety information for planning trips into the winter backcountry, a combination of non-government (Avalanche Canada, Avalanche Quebec) and government (Parks Canada, Kananaskis Country) agencies issue daily public avalanche forecasts for about 20 forecast regions in western Canada and the Chic Chocs in Quebec throughout the winter.

Figure 2 : Total and annual average number of fatalities from meteorological or geological natural hazards in Canada between Oct. 1, 1980 and Sept. 30, 2016 (Avalanche Canada (nd): avalanche fatalities; Public Safety Canada (nd): all other fatalities). Note: Number of fatalities due to cold events and heat events likely underestimated as events with less than 10 fatalities might not be included in Canadian Disaster database.

Figure 2: Total and annual average number of fatalities from meteorological or geological natural hazards in Canada between Oct. 1, 1980 and Sept. 30, 2016 (Avalanche Canada (nd): avalanche fatalities; Public Safety Canada (nd): all other fatalities). Note: Number of fatalities due to cold events and heat events likely underestimated as events with less than 10 fatalities might not be included in Canadian Disaster database.

Considerable efforts are currently underway to reduce avalanche closure times along the Trans-Canada Highway (TCH). Recent installations of snow nets (Cougar Corner west of Rogers Pass, Fig. 3), remote avalanche control systems (e.g., Three Valley Gap) and avalanche detection systems will increase highway reliability substantially by allowing avalanche safety teams to control avalanche hazard more efficiently.

Between 2016 and 2018, the overall avalanche protection related capital expenditures along the TCH will exceed $15 million.

Figure 3 : Installation of snow nets in Cougar Corner, 10 km west of Rogers Pass (source: Brian Gould, Alpine Solutions Avalanche Services)

Figure 3: Installation of snow nets in Cougar Corner, 10 km west of Rogers Pass (source: Brian Gould, Alpine Solutions Avalanche Services)

The risk of human error

Since it is ultimately people deciding when and where to expose themselves to avalanche hazard, improving avalanche safety depends on an in-depth understanding of both the physical phenomenon and the intricacies of the human interaction with it. Avalanche safety research in Canada is therefore taking an interdisciplinary approach that incorporates perspectives and methods from natural, social and medical sciences to examine the factors that lead to avalanche accidents more comprehensively. The close collaboration between academic researchers and avalanche safety practitioners in Canada has created a unique environment for developing practical, evidence-based tools that allow people — both professionals and recreationists — to make better informed decisions about avalanche risk.

Figure 4:  Simulated evolution of seasonal snowpack (source: Simon Horton)

Figure 4: Simulated evolution of seasonal snowpack (source: Simon Horton)

Providing timely avalanche information

The vastness of the Canadian mountains poses a substantial challenge for providing up-to-date avalanche hazard assessments wherever needed. Many industrial applications and transportation routes are remote, and substantial recreational use occurs in areas where the lack of a reliable stream of observations and assessments prevents the publication of public avalanche bulletins.

Recent Canadian research linking numerical snowpack models with weather forecast models has shown that this approach can simulate the snowpack structure at point locations (Fig. 4; e.g., Bellaire, Jamieson, & Fierz, 2011; Côté, Madore, & Langlois, 2017) and the large-scale spatial patterns of critical snowpack layers reasonably well (Horton & Jamieson, 2016). Current research aims to develop operational tools to reliably assess avalanche hazard conditions and inform decision making in otherwise data-sparse regions.

The recreational backcountry community has not only grown dramatically in recent years, but it is also becoming increasingly diverse. Since each user group is unique, an in-depth understanding of their interactions with the mountain landscape, their avalanche awareness levels and their preferred information channels is critical for developing effective safety initiatives. While past research has provided valuable insight (e.g., Haegeli, Gunn, & Haider, 2012; Haegeli, Strong-Cvetich, & Haider, 2012), more human dimensions research is required to design activity-appropriate avalanche safety guidance and ensure effective delivery.

These are just two examples of avalanche safety research directions presently being pursued in Canada. While current avalanche safety initiatives have managed to keep the annual number of avalanche fatalities steady despite the tremendous increase in recreational backcountry activities, innovative solutions will be required to support the continued growth of economic and recreational activities in Canadian mountains.


References

Avalanche Canada. (nd). Avalanche incident database.  Retrieved Sept. 29, 2017 http://old.avalanche.ca/cac/library/incident-report-database/view

Bellaire, S., Jamieson, J. B., & Fierz, C. (2011). Forcing the snow-cover model SNOWPACK with forecasted weather data. The Cryosphere, 5, 1115-1125. doi:10.5194/tc-5-1115-2011

Côté, K., Madore, J.-B., & Langlois, A. (2017). Uncertainties in the SNOWPACK multilayer snow model for a Canadian avalanche context: sensitivity to climatic forcing data. Physical Geography, 38(2), 124-142. doi:10.1080/02723646.2016.1277935

Haegeli, P., Gunn, M., & Haider, W. (2012). Identifying a High-Risk Cohort in a Complex and Dynamic Risk Environment: Out-of-bounds Skiing--An Example from Avalanche Safety. Prevention Science, 13(6), 562-573.

Haegeli, P., Strong-Cvetich, L., & Haider, W. (2012). How mountain snowmobilers adjust their riding preferences in response to avalanche hazard information available at different stages of backcountry trips. Paper presented at the 2012 International Snow Science Workshop, Anchorage, AK. http://arc.lib.montana.edu/snow-science/item/1650

Horton, S., & Jamieson, J. B. (2016). Modelling hazardous surface hoar layers across western Canada with a coupled weather and snow cover model. Cold Regions Science and Technology, 128, 22-31. doi:10.1016/j.coldregions.2016.05.002

Public Safety Canada. (nd). Canadian Disaster Database.  Retrieved Sept. 15, 2017 https://www.publicsafety.gc.ca/cnt/rsrcs/cndn-dsstr-dtbs/index-en.aspx