Natural Hazards

, Volume 91, Issue 1, pp 89–115 | Cite as

Describing the severity of avalanche terrain numerically using the observed terrain selection practices of professional guides

Original Paper
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Abstract

The physical risk from snow avalanches poses a serious threat to mountain backcountry travelers. Avalanche risk is primarily managed by (1) assessing avalanche hazard through analysis of the local weather, snowpack, and recent avalanche activity and (2) selecting terrain that limits exposure to the identified hazard. Professional ski guides have a tremendous wealth of knowledge about using terrain to manage avalanche risk, but their expertise is tacit, which makes it difficult for them to explicitly articulate the underlying decision rules. To make this existing expertise more broadly accessible, this study examines whether it is possible to derive quantitative measures for avalanche terrain severity and condition-dependent terrain guidance directly from observed terrain selection of professional guides. We equipped lead guides at Mike Wiegele Helicopter Skiing with GPS tracking units during the 2014/2015 and 2015/2016 winters creating a dataset of 10,592 high-resolution tracked ski runs. We used four characteristics—incline, vegetation, down-slope curvature (convexities/concavities), and cross-slope curvature (gullies/ridges)—to describe the skied terrain and employed a mixed-effects ordered logistic regression model to examine the relationship between the character of most severe avalanche terrain skied on a day and the associated field-validated avalanche hazard ratings. Patterns in the regression parameter estimates reflected the existing understanding of how terrain is selected to manage avalanche risk well: the guides skied steeper, less dense vegetation, and more convoluted slopes during times of lower avalanche hazard. Avalanche terrain severity scores derived from the parameter estimates compared well to terrain previously zoned according to the Avalanche Terrain Exposure Scale. Using a GIS implementation of the regression analysis, we created avalanche condition-dependent maps that provide insights into what type of terrain guides deemed acceptable for skiing under different avalanche hazard conditions. These promising results highlight the potential of tracking guides’ terrain selection decisions as they manage avalanche hazard for the development of evidence-based avalanche terrain ratings and decision aids for professional and recreational backcountry travelers.

Keywords

Avalanche risk management Avalanche hazard Avalanche terrain classification Condition-dependent terrain guidance Terrain selection Helicopter ski guiding 

Notes

Acknowledgments

We would like to thank the Mike Wiegele Helicopter Skiing and Mitacs for their financial support of this project. Special thanks to Jason Martin and Mike Wheater for their very helpful and careful data collection. The authors would also like to thank the guides at Mike Wiegele’s Helicopter Skiing for their cooperation in carrying GPS units in their packs all winter. Thanks to our colleague Reto Rupf from the Zurich University of Applied Sciences for supplying the GPS units. The Avalanche Research Program at Simon Fraser University is financially supported by Canadian Pacific Railways, HeliCat Canada, Avalanche Canada and Avalanche Canada Foundation, and the Canadian Avalanche Association. We also acknowledge the time and effort that the reviewers spent to provide constructive comments that substantially improved the quality our manuscript.

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Copyright information

© Springer Science+Business Media B.V., part of Springer Nature 2017

Authors and Affiliations

  1. 1.School of Resource and Environmental ManagementSimon Fraser UniversityBurnabyCanada

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