Thesis Front Matter
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UNIVERSITY OF CALGARY Avalanche Terrain Modeling in Glacier National Park, Canada BY Donna M. Delparte A THESIS SUBMITTED TO THE FACULTY OF GRADUATE STUDIES IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY DEPARTMENT OF GEOGRAPHY CALGARY, ALBERTA JANUARY, 2008 © Donna M. Delparte 2008 iii Abstract Snow avalanches are a significant natural hazard that impact roads, structures and threaten human lives in mountainous terrain. Snow avalanche hazard mapping has the potential to reduce this risk by modeling, mapping and visualizing hazardous terrain using Geographic Information Systems (GIS). The Rogers Pass area in Glacier National Park, British Columbia, Canada provides an ideal location for studying well documented avalanche paths that impact the Trans-Canada Highway. Modeling of terrain in a GIS is typically done by utilizing a digital elevation model (DEM). DEM resolution has traditionally been a limiting factor in the evaluation of terrain at a slope scale. The best available DEM data for this area has a resolution of 25 m. Using a procedure of digital stereo photogrammetry, an improved DEM of higher resolution was generated for this research. This technology allows a GIS operator wearing stereo goggles to digitally resample surface heights using stereo-photo pairs. Topographic parameters such as slope, aspect, curvature and distance from ridges were derived from the DEM. To evaluate what terrain parameters are most likely to contribute to avalanche activity, expert knowledge from known avalanche paths was documented and statistically evaluated for these key factors. In addition, the alpha-beta statistical model, first used by the Norwegian Geotechnical Institute, was adapted for estimating maximum snow avalanche runout in the Rogers Pass area based upon the detailed avalanche record from the highway corridor. Along roadways or in areas where there is a human presence, details of avalanche runout distance are often recorded; however areas in the backcountry typically traveled by recreationists may not have a recorded history of avalanche activity or runout distances. Patterns from well known avalanche occurrences along the highway corridor were transferred to map avalanche hazard in more remote areas of the region using the derived terrain characteristics, runout model and a GIS algorithm (Avalanche Terrain Exposure Scale) to map avalanche terrain into clear categories of terrain exposure. The results are useful in supplementing traditional field based methods of avalanche hazard mapping as well as providing a tool for risk assessment. iv Preface This thesis explores the use of Geographic Information Systems (GIS) for avalanche hazard and terrain mapping. GIS and digital elevation data offer a means to explore the nuances of terrain that contribute to avalanche formation and release. This thesis describes the process of developing an avalanche runout model for the Columbia Mountains and a preliminary algorithm for determining avalanche exposure. The research presented in this thesis offers a foundation for GIS and avalanche experts to build further understanding and applications in the use of GIS and digital data to aid in decision- making with respect to avalanche terrain. The GIS maps produced in this thesis are not verified representations of avalanche exposure and no attempt should be made to navigate or make route decisions based on the maps presented in this paper. This thesis is not intended as a guide for backcountry users. Backcountry travel has inherent risks and there is always the potential for avalanches in the terrain described. v Acknowledgements I would like to gratefully acknowledge Dr. Nigel Waters and Dr. Bruce Jamieson for their contributions, insight, guidance and support throughout the process of completing this PhD thesis. I would also like to thank the other members of my examination committee, Drs. Shawn Marshall, Tak Fung and Karl Birkeland for their time in reviewing this thesis and their constructive comments. This research would not have been possible without the support provided by an anonymous donor grant through the University of Calgary and is gratefully acknowledged. I would like to thank Graham Bruce for acting as facilitator for this anonymous grant. I would like to acknowledge and thank Bruce McMahon for the many hours he contributed to identifying topographic features in the GIS for this study and to both his and Grant Statham’s input on developing a GIS algorithm based on how experts think about classifying avalanche terrain. I would also like to thank Dr. Tak Fung of the University of Calgary for statistical analysis support and to Janet Rose for her technical knowledge and assistance with regards to digital elevation mapping. In terms of computer and software support, I’d like to acknowledge Bruce Park for his tremendous and timely assistance as well as his words encouragement at many stages of this research. Thanks also to Ron Perla for his insightful comments and discussion on avalanche runout models. In April of 2007, I received a Graduate Conference Travel Grant from the University of Calgary Research Grants Committee which allowed me to make two presentations at the European Geosciences Union General Assembly in Vienna, Austria. This opportunity allowed me to present the runout model and the algorithm for avalanche hazard mapping in the Columbia Mountains. vi I would like to extend my appreciation to Dr. Nigel Waters for creating the opportunity to present this PhD research at the Core-to-Core Workshop at Schloss Dagstuhl, Germany in July of 2006 and for providing assistance with my travel expenses. The support of the Selkirk College Professional Development Committee is gratefully recognized for providing one year of professional development funding as well as additional funds to cover travel expenses for numerous conferences, training opportunities and events. In addition, I would like to thank Selkirk College and the Selkirk Geospatial Research Centre for the use of leading-edge technical equipment and data support. My former colleagues at Selkirk College were always supportive and encouraging of my research efforts and future plans and for this I am very appreciative. I would like to acknowledge the support and encouragement of my parents, Don and Kay Delparte as well as all my friends who encouraged me in the pursuit of my PhD and with whom I have shared many special times in the outdoors, especially on skiing and whitewater kayaking adventures. Particular thanks to Paula Vaananen, Dave Larocque, Laura Adams, Rob D’Eon, Brendan Wilson and Marnie Laser. Finally, thanks to my husband Rick Richardson for his support and for being my partner in a life of adventure on rock, snow and water. vii Table of Contents Approval Page..................................................................................................................... ii Abstract.............................................................................................................................. iii Preface................................................................................................................................ iv Acknowledgements..............................................................................................................v Table of Contents.............................................................................................................. vii List of Tables .......................................................................................................................x List of Figures................................................................................................................... xii List of Symbols, Abbreviations and Nomenclature......................................................... xvi CHAPTER ONE: INTRODUCTION..................................................................................1 1.1 Background and rationale ..........................................................................................1 1.2 Snow avalanches........................................................................................................5 1.2.1 Description and classification............................................................................5 1.2.2 Avalanche formation and release ......................................................................9 1.2.3 Avalanche frequency, return period and encounter probability ......................11 1.3 Understanding risk, hazard and danger in avalanche terrain mapping ....................13 1.3.1 Risk and hazard ...............................................................................................14 1.3.2 Avalanche danger ............................................................................................16 1.3.2.1 Avalanche Terrain Exposure Scale (ATES) ..........................................20 1.4 Location and general description of the study area .................................................22 1.4.1 Datasets and avalanche database of the study area .........................................28 1.5 Statement of goals and objectives............................................................................32 1.6 Thesis structure........................................................................................................34 CHAPTER TWO: LITERATURE REVIEW....................................................................36 2.1 Introduction..............................................................................................................36