Item: AVALANCHE HAZARD ASSESSMENT: THE PROBABILISTIC VS. ANALYTICAL APPROACH – THE WELL-CHERISHED DICHOTOMY
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Title: AVALANCHE HAZARD ASSESSMENT: THE PROBABILISTIC VS. ANALYTICAL APPROACH – THE WELL-CHERISHED DICHOTOMY
Proceedings: International Snow Science Workshop 2024, Tromsø, Norway
Authors:
- Jürg Schweizer [ WSL Institute for Snow and Avalanche Research SLF, Davos Dorf, Switzerland ]
- Christoph Mitterer [ Avalanche Warning Service Tyrol, Innsbruck, Austria ]
- Benjamin Reuter [ Météo-France, Direction des opérations pour la prévision, Toulouse, France ] [ Univ. Grenoble Alpes, Univ. de Toulouse, Météo-France, CNRS, CNRM, Centre d'Etudes de la Neige, Grenoble, France ]
Date: 2024-09-23
Abstract: Assessing avalanche risk in the backcountry is a challenging task. First and foremost since avalanche hazard cannot be accurately determined: We do not know snow stability in space and time with sufficient accuracy. Therefore, it is not surprising that many approaches have been suggested for assessing avalanche hazard when travelling in the backcountry – ever since the first educational avalanche book has been published. Given the uncertainty due to the insufficiently known stability of the snowpack, most approaches rely on experience, comparing contributory factors of avalanche formation to avalanche occurrence. They were developed from rules of thumb to quantitative statistical analyses, to the present machine learning models. For backcountry travelers, the era of the probabilistic approaches started with the advent of Munter’s reduction method – and variants thereof derived subsequently. These methods were promoted in contrast to what was termed the analytical approach which essentially involves assessing and weighing the contributory factors to avalanche formation. Obviously, these terms – probabilistic and analytical – are ill-posed, since any approach can only describe the hazard with a relative probability. We suggest leaving the dichotomy behind, describing the approaches as knowledge-based and rule-based, and moving forward toward a comprehensive risk assessment. The latter implies combining estimates of release probability and consequences, taking into account adequate risk reduction measures, and finally assessing the risk. Such a primarily knowledge-based approach considers simple and relevant observations for both estimating the release probability and the consequences, and builds on our present understanding of avalanched release
Object ID: ISSW2024_O12.1.pdf
Language of Article: English
Presenter(s): Jürg Schweizer
Keywords: avalanche danger, risk assessment, decision-making, backcountry touring
Page Number(s): 1604 - 1608
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