Theses and Dissertations at Montana State University (MSU)

Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/733

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A framework for the quantitative assessment of new data streams in avalanche forecasting
(Montana State University - Bozeman, College of Letters & Science, 2023) Haddad, Alexander Sean; Co-chairs, Graduate Committee: Eric A. Sproles and Jordy Hendrikx
Data used by avalanche forecasters are typically collected using weather stations, manual field-based observations (e.g., avalanche events, snow profiles, stability tests, personal observations, public observations, etc.) and weather forecasts ("traditional observations"). Today, snow cover observations can be delivered via remote sensing (e.g., satellite data, UAV, TLS, time-lapse camera etc.). Forecasting operations can also use statistical forecasting, weather models, and physical modeling to support decisions. This paper presents a framework and methodology to quantify the impact these new, complex data streams have on the formulation of, and associated uncertainty of, avalanche forecasting. We use data from a case study in Norway. Avalanche forecasters in Norway assessed size (D), likelihood, avalanche problem, and hazard level for a highway corridor in Grasdalen, Stryn Norway. The control groups were given access to traditional observations. The experimental groups were given access to the same traditional data, but also near-real-time snow surface LiDAR data ("RS+"). In case study one the RS+ (n=10) consensus findings were a hazard level two steps lower than the control group (n=10). In case study two the traditional (n=10) and RS+ groups' (n=7) consensus findings assessed the northeastern avalanche path at the same hazard level. Assessing the southwestern slide path, the traditional group (n=10) and RS+ group (n=9) had the same consensus finding for hazard level. In 2 of 3 case studies, the RS+ groups had fewer selections for size, likelihood, and avalanche problem which indicates reduced uncertainty in their forecasts. Throughout the 2022-2023 winter season Norwegian Public Roads Administration avalanche forecasters performed a real-time experiment throughout the season - with and without additional RS+ data when forecasting. They agreed on hazard level in 6 of 10 forecasts. In the other 4 forecasts, RS+ forecasters assessed the hazard level higher than traditional data forecasts. When RS+ data reveals aspects of conditions that traditional observations did not detail, RS+ forecasters adjust their selections in the hazard matrix, resulting in greater clustering of their predictions, indicating reduced uncertainty. Due to uncertainty associated with avalanche forecasting, this framework for assessment should be used to track avalanche forecast efficacy and build a qualitative and quantitative historical record.
Meteorological controls on wind slab properties
(Montana State University - Bozeman, College of Letters & Science, 2023) de Leeuw, Nathalie Marika; Chairperson, Graduate Committee: Jordy Hendrikx
Snow avalanches are dangerous phenomena, which can be made increasingly consequential through wind transport of snow. Wind-deposited snow has a broad range of possible physical and mechanical properties which can vary greatly over short distances, creating inconsistent and thus difficult avalanche conditions. This variability causes particular challenges for avalanche workers in data-sparse regions where important snowpack information at desired scales may be unavailable. Instead, snowpack properties are commonly inferred from available meteorological data. Though wind slab properties vary in space and time as meteorological conditions change, previous work has not explicitly studied these relationships at the slope-scale. In this research I aim to better understand how changes in meteorological variables relate to changes in wind slab physical properties. During two winters I recorded temperature, humidity, and wind speed at study sites in Montana's Madison Range (45.237, -111.424) and collected snowpack data during or immediately following blowing snow events. I found that average wind speeds at 0.5m and 1.5m above the snow surface were significantly higher during hard wind slab formation than soft wind slab formation, while unobstructed wind speed, maximum gust, and the length of time of wind transport were not associated with wind slab hardness. Temperature was higher during hard than soft wind slab formation, while humidity was not different between the two hardness categories. Although wind speed at 1.5m had a significant positive linear relationship with both wind slab density and blade hardness gauge force, it was a poor predictor of actual values for both of these parameters. Our findings help improve the understanding of the impact of near surface winds on wind slabs, which will aid avalanche forecasting and mitigation planning particularly in windy climates.
Spatio-temporal analysis of large magnitude avalanches using dendrochronology
(Montana State University - Bozeman, College of Letters & Science, 2020) Peitzsch, Erich Hans; Chairperson, Graduate Committee: Jordy Hendrikx; Jordy Hendrikx, Daniel K. Stahle, Gregory T. Pederson, Karl W. Birkeland and Daniel B. Fagre were co-authors of the article, 'A regional spatio-temporal analysis of large magnitude snow avalanches using tree rings' submitted to the journal 'Natural hazards and Earth systems sciences' which is contained within this dissertation.; Gregory T. Pederson, Jordy Hendrikx, Karl W. Birkeland and Daniel B. Fagre were co-authors of the article, 'Trends in regional large magnitude snow avalanche occurrence and associated climate patterns in the U.S. northern Rocky Mountains' submitted to the journal 'Journal of climate' which is contained within this dissertation.; Chelsea Martin-Mikle, Jordy Hendrikx, Gregory T. Pederson, Karl W. Birkeland and Daniel B. Fagre were co-authors of the article, 'Vegetation characterization in avalanche paths using LIDAR and satellite imagery' submitted to the journal 'Arctic, antarctic, and alpine research' which is contained within this dissertation.
Snow avalanches are a natural hazard to humans and infrastructure as well as an important landscape disturbance affecting mountain ecosystems. In many mountainous regions, records of avalanche frequency and magnitude are sparse or non-existent. Inferring historic avalanche patterns to improve forecasting and understanding requires the use of dendrochronological methods. In this dissertation, we examine a regional tree-ring derived large magnitude avalanche dataset from northwest Montana in the northern Rocky Mountains, USA, to produce avalanche chronologies at three distinct scales (path, sub-region, and region), assess seasonal climate drivers of years with large magnitude avalanche occurrence on a regional scale, and characterize vegetation in select avalanche paths. By implementing a strategic spatial sampling design and collecting a large dataset of tree-ring samples, we: (1) assessed scaling in the context of a regional avalanche chronology, reconstructed avalanche chronologies for 12 avalanche paths in four subregions, and examined the effects of two methods of sampling indexing on the resultant avalanche chronology; (2) identified specific climate drivers of large magnitude avalanche years across a region and identified trends in avalanche year probability through time; and (3) tested the feasibility of using remote sensing products to quantify vegetation types in avalanche paths and characterized the vegetation composition based on return periods within specific avalanche paths. This dissertation is organized into 3 key chapters/manuscripts (Chapters 2, 3, and 4) and two supporting chapters (Chapters 1 and 5) that address the problem of assessing large magnitude avalanche frequency at various spatio-temporal scales using a tree-ring dataset. The results contribute toward a better understanding of reconstructing regional avalanche chronologies, a more accurate assessment of avalanche-climate relationships, and improved methods to characterize vegetation characteristics within avalanche path return periods. This work has applications for regions with sparse avalanche records.
Data analytics and software to support avalanche forecasting decisions
(Montana State University - Bozeman, College of Engineering, 2021) Ottsen, Peter Kenneth; Chairperson, Graduate Committee: Sean Yaw
Avalanches are a very powerful force of nature and pose significant risk for ski areas and mountainous roads. Avalanche forecasting and mitigation are a very important part of keeping the public safe. Terrestrial laser scanning lidar systems have proven useful in more accurate forecasting and mitigation efforts, but utilizing them can be time consuming. The goal of this project is to operationalize a workflow and create algorithms and ultimately produce a software product that can rapidly analyze snow covered mountainous terrain, allowing avalanche forecasters to make informed decisions on where to focus their mitigation efforts. In this dissertation, I first present algorithms that were designed to align scans, identify trees and cliffs, grid scans, and calculate snow depth. I then introduce a software package that was implemented incorporating these algorithms with a point cloud visualization tool. This software package allows a user to control and visualize the analysis process to make more informed avalanche mitigation decisions. Algorithms were parameterized and validated with a field study consisting of data collection events at Bridger Bowl, Bear Canyon, and the Yellowstone Club in Montana. A Riegl VZ-6000 TLS lidar system was used for all data collection efforts. This dissertation documents the design of this analytics workflow by presenting the algorithms developed, discussing the software implemented, and presenting the data collection efforts that guided the design of the algorithms and served to validate their efficacy.
Snow avalanche identification using Sentinel-1: detection rates and controlling factors
(Montana State University - Bozeman, College of Letters & Science, 2021) Keskinen, Zachary Marshall; Chairperson, Graduate Committee: Jordy Hendrikx; Jordy Hendrikx, Karl Birkeland and Markus Eckerstorfer were co-authors of the article, 'Snow avalanche identification using Sentinel-1 backscatter imagery: detection rates and controlling factors' submitted to the journal 'Natural hazards and Earth system sciences' which is contained within this thesis.
Snow avalanches present a significant hazard that endangers lives and infrastructure. Consistent and accurate datasets of avalanche events is valuable for improving forecasting ability and furthering knowledge of avalanches' spatial and temporal patterns. Remote sensing-based techniques of identifying avalanche debris allow for continuous and spatially consistent datasets of avalanches to be acquired. This study utilizes expert manual interpretations of Sentinel-1 synthetic aperture radar (SAR) satellite backscatter images to identify avalanche debris and compares those detections against historical field records of avalanches in the transitional snow climates of Wyoming and Utah. This study explores the utility of Sentinel-1 (a SAR satellite) images to detect avalanche debris on primarily dry slab avalanches. The overall probability of detection (POD) rate for avalanches large enough to destroy trees or bury a car (i.e., D3 on the Destructive Size Scale) was 64.6%. There was a significant variance in the POD among the 13 individual SAR image pairs (15.4 - 87.0%). Additionally, this study investigated the connection between successful avalanche detections and SAR-specific, topographic, and avalanche type variables. The most correlated variables with higher detection rates were avalanche path lengths, destructive size of the avalanche, incidence angles for the incoming microwaves, slope angle, and elapsed time between the avalanche and a Sentinel-1 satellite passing over. This study provides an initial exploration of the controlling variables in the likelihood of detecting avalanches using Sentinel-1 backscatter change detection techniques. This study also supports the generalizability of SAR backscatter difference analysis by applying the methodology in different regions with distinct snow climates from previous studies.
Measuring explosive airblast of remote avalanche control systems
(Montana State University - Bozeman, College of Engineering, 2021) Seitz, Brandt Kolden; Chairperson, Graduate Committee: Robb Larson
This research was established to evaluate the explosive blast waves from operational remote avalanche control systems (RACS). Testing was performed on Gazex, O'Bellx, and Wyssen Tower systems installed near Alta, Utah. Air pressures were measured in many directions and at a range of distances around each explosive using high-pressure microphones and custom measurement equipment. The air pressure data from each system was then evaluated based on the peak pressures generated, effective blast wave energy, the rate at which pressure increased, and the decay of these parameters with distance. Distinct differences, and some similarities, between the explosives tested were found that both validated and expanded upon previous research efforts. It was found that an 11-lb Pentolite charge (designed to be deployed from a Wyssen Tower) had the strongest effects overall, followed by the standard 11-lb gel emulsion charge from a Wyssen Tower, then by the 1.5 m 3 Gazex system (which was comparable to the gel charge in the direction of the exploder, but weaker in other directions), and lastly by the O'Bellx system (which had a more localized, but more symmetric, effect than the Gazex). In addition, many other tests were conducted utilizing 2-lb Pentolite charges, simulated Avalanche Guard charges, flat-field testing of Wyssen Tower gel emulsion and Pentolite charges, and explosives or RACS placed near unique terrain features. The 2-lb Pentolite testing validated the instrumentation for this project and showed that the equipment performed similarly to other systems from prior research efforts. The simulated Avalanche Guard charge was shown to have a very similar effect to the 11-lb gel emulsion charge. Flat-field testing of the Wyssen Tower charges showed similar blast wave strengths as was observed at the operational tower but indicated differences in the symmetry of the waves when compared to the operational tower. Lastly, the initial investigation of terrain features indicated that features such as cliffs and gullies can increase the directionality of an explosive. Overall, this work will provide avalanche control experts with much needed performance data on operational RACS and will also help to facilitate future work in this subject area.
Atmospheric processes related to deep persistent slab avalanches in the western United States
(Montana State University - Bozeman, College of Letters & Science, 2019) Schauer, Andrew Robert; Chairperson, Graduate Committee: Jordy Hendrikx
Deep persistent slab avalanches are a natural hazard that are particularly difficult to predict. These avalanches are capable of destroying infrastructure in mountain settings, and are generally unsurvivable by humans. Deep persistent slab avalanches are characterized by a thick (> 1 m) slab of cohesive snow overlaying a weak layer in the snowpack, which can fail due to overburden stress of the slab itself or to external triggers such as falling cornices, explosives, or a human. While formation of such snowpack structure is controlled by persistent weather patterns early in the winter, a snowpack exhibiting characteristics capable of producing a deep persistent slab avalanche may exist for weeks or months before a specific weather event such as a heavy precipitation or rapid warming pushes the weak layer to its breaking point. Mountain weather patterns are highly variable down to the local scale (1-10 m), but they are largely driven by atmospheric processes on the continental scale (1000 km). This work relates atmospheric circulation to deep persistent slab events at Mammoth, CA; Bridger Bowl, MT; and Jackson, WY. We classify 5,899 daily 500 millibar geopotential height maps into 20 synoptic types using Self-Organizing Maps. At each location, we examine the frequency of occurrence of each of the 20 types during November through January during major deep persistent slab seasons and compare those frequencies to seasons without deep persistent slab avalanches. We also consider the 72-hour time period preceding deep persistent slab avalanches at each location and identify synoptic types occurring frequently, as well as those rarely occurring prior to onset of activity. At each location, we find specific synoptic types that tend to occur at a higher rate during major deep persistent slab years, while minor years are characterized by different circulation patterns. We also find a small number of synoptic types dominating the 72-hour period prior to onset of deep slab activity. With this improved understanding of the atmospheric processes preceding deep persistent slab avalanches, we provide avalanche practitioners with an additional tool to better anticipate a difficult to predict natural hazard.
Travel behavior and decision-making biases of lift access backcountry skiers on Saddle Peak, Bridger Mountains, Montana, USA
(Montana State University - Bozeman, College of Letters and Science, 2018) Sykes, John Massey; Chairperson, Graduate Committee: Jordy Hendrikx; Jordy Hendrikx, Jerry Johnson and Karl Birkeland were co-authors of the article, 'Travel behavior and decision-making biases of lift access backcountry skiers' submitted to the journal 'Applied geography' which is contained within this thesis.
Backcountry skiers recreate in a complex environment, with the goal of minimizing the risk of avalanche hazard and maximizing recreational opportunities. Traditional backcountry outings start and end in uncontrolled backcountry settings, with responsibility for avalanche safety and rescue falling in the hands of each group of skiers. Lift access backcountry skiing (LABC) is a particular genre of the sport in which ski resort lifts are utilized to access backcountry recreation sites. By shifting skiers mentality from the traditional backcountry setting to a LABC setting, the line between whether the ski resort provides avalanche mitigation and rescue services or not, becomes less clearly defined in the minds of skiers. We observe the travel behavior and evaluate the decision-making biases of LABC skiers via GPS tracking and survey responses. Participants were recruited in the field, at the boundary between the relative safety of the ski resort and the uncontrolled backcountry terrain beyond. A geographic information system (GIS) is implemented to analyze the travel behavior of participants, with the aim to detect changes in behavior, as indexed via terrain used under different levels of avalanche hazard. Logistic regression and multiple linear regression are used to model travel behavior and decision-making biases as a function of observed terrain metrics. Data was collected over 19 days from February 2017 to February 2018 at Saddle Peak backcountry area, a prime LABC location at the southern boundary of Bridger Bowl Ski Area, Montana, USA. Avalanche hazard during data collection was either moderate (119 tracks) or considerable (20 tracks). Regression models indicate subtle changes in the terrain preferences of participants under elevated avalanche hazard, with increased travel on ridge features and decreased use of convex features. These indicate a positive response, minimizing the risk of an avalanche involvement by managing slope shape. Survey responses indicate that female participants and those with greater backcountry experience have a significantly lower percentage of their total GPS track in complex avalanche terrain as defined using the avalanche terrain exposure scale. Participants who perceived the ski patrol as providing avalanche mitigation in the backcountry area adjacent to the resort had a significantly higher percentage of GPS track in complex avalanche terrain.
Using time lapse photography to document terrain preferences of backcountry skiers
(Montana State University - Bozeman, College of Letters & Science, 2018) Saly, Diana Ilona Patricia; Chairperson, Graduate Committee: Jordy Hendrikx; Jordy Hendrikx, Karl W. Birkeland, Stuart Challender and Jerry Johnson were co-authors of the article, 'Using time lapse photograpy to document terrain preferences of backcountry skiers' submitted to the journal 'Journal of outdoor recreation and tourism' which is contained within this thesis.
Avalanches are one of the greatest hazards for those recreating in snow covered mountainous terrain. In the past 20 years an average of 13 people in Canada and 27 people in the US are killed in avalanches each winter. Meanwhile, uncontrolled backcountry avalanche terrain use has significantly increased demonstrated by increased demand for avalanche education and increased sales in backcountry equipment. Lift-accessed backcountry (LABC), or avalanche terrain easily accessed from the ski resort, has seen increased usage since resorts opened boundaries in the mid-1990s. This has led to increased research interest in how people are using backcountry avalanche terrain. A simple method to reduce exposure to avalanche hazard is avoidance, however total avoidance is seldom practical. Professionals and recreational skiers alike mitigate avalanche hazard by managing exposure to terrain containing the avalanche hazard. Current research studies use GPS tracking to study the terrain metrics of backcountry skiers. This GPS research is limited to studying volunteers and professionals that willingly track and submit their trips. This approach ignores many users and thus presents a biased picture of use. This paper develops a method to capture the terrain metrics of all skiers on an avalanche-prone backcountry slope. A remote time-lapse camera focused on a high skier-use backcountry slope, (Saddle Peak, in the Bridger Mountain Range of southwest Montana, USA) captured skiers descending Saddle Peak in ten-second increments. Skier locations were digitized from the photos, then transformed onto a geo-referenced digital elevation model (DEM) such that terrain metrics could be applied to each skier location. Analysis of terrain metrics for each skier point compared slope, profile curvature (downslope), and plan curvature (cross slope) over days with different forecasted avalanche hazard. Terrain metrics on Considerable avalanche hazard days differed significantly from Moderate or Low avalanche hazard days (p-value < 0.001). Transformed data fell within a 49-m horizontal accuracy for all skier point locations with a 95% confidence interval. By capturing all skiers on a slope without their knowledge, the data collected provides a large and diverse data set of the terrain preferences of backcountry skiers under varying conditions.
Snow drift and avalanche activity in a high arctic maritime snow climate
(Montana State University - Bozeman, College of Letters & Science, 2016) Hancock, Holt John; Chairperson, Graduate Committee: Jordy Hendrikx
Snow drift endangers human life and infrastructure in alpine and arctic environments by contributing to snow avalanche formation in steep terrain and impacting transportation through reduced visibilities and drift deposition on roadways. Understanding the local and synoptic scale meteorological conditions just prior to and during hazardous snow drift conditions is a crucial element in forecasting for -- and mitigating the hazards associated with -- snow drift processes. This is especially true in Svalbard, a High Arctic Norwegian archipelago, where snow drift processes have been linked to avalanche activity and hazardous travel conditions in the region's unique, direct-action maritime snow climate. This study uses a record of road closures due to drifting snow on a mountain road to further investigate Svalbard's snow climate and avalanche regime by characterizing meteorological conditions leading to regional snow drift events and exploring the relationship between these periods of snow drift and regional avalanche activity. A nine-year record of road closures is coupled with local meteorological observations and NCEP/NCAR synoptic composite maps to characterize the local and synoptic weather conditions leading to and occurring during periods of snow drift near Longyearbyen, Svalbard's primary settlement. This record of snow drift events is then compared with regional avalanche observations using a case study approach to illustrate the relationship between snow drift and avalanche activity in Svalbard. Results show snow drift events result from five distinct synoptic circulation types and are characterized by increased wind speeds, higher precipitation totals, and elevated air temperatures relative to average winter conditions. Four case studies qualitatively illustrate the interactions between local and synoptic weather patterns, snow drift processes, and regional avalanche activity. In addition to the suggested mitigation strategies provided, these results will help advance avalanche forecasting efforts throughout the region.

Theses and Dissertations at Montana State University (MSU)

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