Item: 50 SHADES OF BLUE: RISK GRADIENTS WITHIN AVALANCHE HAZARD ZONES
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Title: 50 SHADES OF BLUE: RISK GRADIENTS WITHIN AVALANCHE HAZARD ZONES
Proceedings: International Snow Science Workshop 2024, Tromsø, Norway
Authors:
- Chris Argue [ Dynamic Avalanche Consulting, Revelstoke, BC, Canada ]
Date: 2024-09-23
Abstract: Avalanche hazard zone maps for occupied structures in North America and Europe are typically based on a combination of avalanche frequency and impact pressure, and land-use decisions are often based solely on the hazard zoning. However, there is an emerging recognition by practitioners that because (by definition) avalanche magnitude and frequency can vary widely within each hazard zone, overly restrictive land-use decisions or mitigation prescriptions are possible when regulation follows the zoning. As the vulnerability of structures and people depend strongly on impact pressure, we would expect the risk to vary widely across the hazard zones, and on that basis, it is unlikely that optimal land-use and mitigation regulation can span a hazard zone uniformly. In this paper, we explore the limitations of hazard zone maps through a case study by comparing a hazard zone map to a risk index map. We discuss possible applications of risk index maps to land-use regulation in place of or alongside hazard zone maps. To do this, we borrow concepts and techniques developed for other rapid slope geohazards such as landslides. Our results in this case study show that, for the most part, similar land-use decisions would have been made with either approach, but there are some meaningful differences. The risk index maps identify where land-use planning decisions may be overly conservative if based on hazard criteria alone. An exploration of the risk gradients within the hazard zones can be a valuable tool for practitioners and land-use regulators to manage avalanche risk in an efficient and optimal way.
Object ID: ISSW2024_O7.9.pdf
Language of Article: English
Presenter(s): Chris Argue
Keywords: Risk, hazard, zoning, mapping, land use
Page Number(s): 853 - 859
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