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

Nat. Hazards Earth Syst. Sci.

Mair

2019

Self Cite

While guides in mechanized skiing operations use a well-established terrain selection process to limit their exposure to avalanche hazard and keep the residual risk at an acceptable level, the relationship between the open/closed status of runs and environmental factors is complex and has so far only received limited attention from research. Using a large dataset of over 25 000 operational run list codes from a mechanized skiing operation, we applied a general linear mixed-effect model to explore the relationship between skiing terrain that is deemed appropriate for guiding (i.e., status open) and avalanche hazard conditions. Our results show that the magnitude of the effect of avalanche hazard on run list codes depends on the type of terrain that is being assessed by the guiding team. Ski runs in severe alpine terrain with steep lines through large avalanche slopes are much more susceptible to increases in avalanche hazard than less severe terrain. However, our results also highlight the strong effects of recent skiing on the run coding and thus the importance of prior first-hand experience. Expressing these relationships numerically provides an important step towards the development of meaningful decision aids, which can assist commercial operations to manage their avalanche risk more effectively and efficiently.

Section: Overall Insight Into the Effect Of Avalanche Hazardsupporting

confidence: 73%

Exploring the relationship between avalanche hazard and run list terrain choices at a helicopter skiing operation

Nat. Hazards Earth Syst. Sci.

Mair

2019

Self Cite

“…Hence, each of the ski runs included in our analysis is characterized by a multi-season time series of daily run list ratings. Since large datasets with many attributes are challenging for traditional clustering techniques (Assent, 2012), we applied a two-step approach that combines the strengths and efficiency of self-organizing maps (SOMs; Kohonen, 2001), an unsupervised competitive neural network clustering algorithm, with the transparency of traditional hierarchical clustering (Vesanto and Alhoniemi, 2000;Gonçalves et al, 2008). This approach circumvents the challenge of the large dataset by first using SOMs to produce an analysis dataset with substantially fewer items that represent meaningful averages and are less sensitive to random variations than the run list time series included in the original data.…”

Section: Identifying Run Groups and Overall Ski Run Hierarchymentioning

confidence: 99%

A method of deriving operation-specific ski run classes for avalanche risk management decisions in mechanized skiing

Nat. Hazards Earth Syst. Sci.

2019

Self Cite

Abstract. An in-depth understanding of the nature of the available terrain and its exposure to avalanche hazard is crucial for making informed risk management decisions when travelling in the backcountry. While the Avalanche Terrain Exposure Scale (ATES) is broadly used for providing recreationists with terrain information, this type of terrain classification has so far only seen limited adoption within the professional ski guiding community. We hypothesize that it is the generic nature and small number of terrain classes of ATES and its precursor systems that prevent them from offering meaningful assistance to professional decision makers. Working with two mechanized skiing operations in British Columbia, Canada, we present a new approach for deriving terrain classifications from daily terrain assessment records. We used a combination of self-organizing maps and hierarchical clustering to identify groups of ski runs that have been assessed similarly in the past and organized them into operation-specific ski run hierarchies. We then examined the nature of the emerging ski run hierarchies using comprehensive run characterizations from experienced guides. Our approach produces high-resolution ski run hierarchies that offer a more nuanced and meaningful perspective on the available skiing terrain and provide new opportunities for examining professional avalanche risk management practices and developing meaningful decision aids.

“…To identify meaningful patterns between avalanche hazard and terrain choices numerically, it is critical to encode the nature of the available ski runs in a concise, but insightful way. Avalanche terrain research in the context of backcountry recreation has traditionally primarily focused on standard terrain characteristics such as slope incline, slope shape, elevation, aspect, and vegetation density (e.g., Hendrikx et al, 2016;Thumlert and Haegeli, 2018). More recently, Harvey et al (2018) developed a more sophisticated approach that combines an automated identification of potential avalanche release areas with avalanche simulations using RAMMS::EXTENDED (Bartelt et al, 2012;Bartelt et al, 2016) and fall simulations to develop thematic avalanche terrain maps that identify potential avalanche release areas, remote triggering of avalanches, possible runout zones, and the potential of being seriously injured or deeply buried by small or medium-sized avalanches.…”

Section: Data Setmentioning

confidence: 99%

“…As the season progresses, runs that have been skied before and where the guiding team has recent observations about the specific conditions on that run are opened Together, these effects underline the necessity for analysing professional terrain choices in their temporal context. While revealed terrain preference data from GPS tracking units (e.g., Hendrikx et al, 2016;Thumlert and Haegeli, 2018) offer promising avenues for learning about professional avalanche risk management expertise at spatial scales below the run level, it is important to remember that these terrain decisions cannot be analysed as independent, isolated samples as they are always made in an operational context. It is therefore imperative to analyse the observations in the proper temporal context (i.e., open previously, skied previously) and spatial context (run list codes, run use, skied line on a run) to extract meaningful relationships between hazard and terrain choices that can be generalized.…”

Section: Effect Of Run Code Of the Previous Day And Recent Skiing On mentioning

confidence: 99%

“…Grímsdottír (2004) and Haegeli (2010) identified critical terrain and avalanche hazard factors contributing to the terrain decisions at the run scale but did not examine the relationship between avalanche hazard conditions and run list codings in more detail. While Hendrikx et al (2016) and Thumlert and Haegeli (2018) studied the association between small-scale terrain choices and avalanche conditions quantitatively by analyzing patterns in GPS tracks, they did not account for the fact that these choices are embedded in a higher-level, hierarchical and continuous terrain selection process. Having an in-depth, quantitative understanding of each stage of the terrain selection process is critical for properly tapping into the risk management practices of guiding teams and describing it in a way that offers useful insight into the influencing factors.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Exploring the relationship between avalanche hazard and large-scale terrain choices at a helicopter skiing operation – Insight from run list ratings

Mair

2019

Preprint

Self Cite

Abstract. While guides in mechanized skiing operations use a well-established terrain selection process to limit their exposure to avalanche hazard and keep the residual risk at an acceptable level, the relationship between the open/closed status of runs and environmental factors is complex and has so far only received limited attention from research. Using a large data set of over 25 000 operational run list codes from a mechanized skiing operation, we applied a general linear mixed effects model to explore the relationship between acceptable skiing terrain (i.e., status open) and avalanche hazard conditions. Our results show that the magnitude of the effect of avalanche hazard on run list codes depends on the type of terrain that is being assessed by the guiding team. Ski runs in severe alpine terrain with steep lines through large avalanche slopes are much more susceptible to increases in avalanche hazard than less severe terrain. However, our results also highlight the strong effects of recent skiing on the run coding and thus the importance of prior first-hand experience. Expressing these relationships numerically provides an important step towards the development of meaningful decision aids, which can assist commercial operations to manage their avalanche risk more effectively and efficiently.