Master Thesis, Department of Geosciences Dynamic avalanche modeling in Svalbard’s arctic environment Terrestrial laser scanning as a tool for model verification Mari Eiken Dynamic avalanche modeling in Svalbard’s arctic environment Terrestrial laser scanning as a tool for model verification Mari Eiken Master Thesis in Geosciences Physical Geography, Hydrology, and Geomatics Department of Geosciences Faculty of Mathematics and Natural Sciences University of Oslo March 2017 ©Mari Eiken, 2017 This work is published digitally through DUO – Digitale Utgivelser ved UiO http://www.duo.uio.no It is also catalogued in BIBSYS (http://www.bibsys.no/english) All rights reserved. No part of this publication may be reproduced or transmitted, in any form or by any means, without permission. This thesis was conducted and completed on Svalbard, as part of a guest master student contract at the University Centre in Svalbard (UNIS). Cover photo: Holt Hancock Abstract Every year avalanches are observed near, or in, Longyearbyen, Svalbard’s largest settlement, making continuous development of hazard management strategies through research and experience highly relevant. In this thesis, four real avalanche events in the 2015/2016 winter season are investigated using a terrestrial laser scanner. The high-resolution data obtained using this method is used for validation of the two- dimensional numerical avalanche model RAMMS. Through analysis of runout simulations in RAMMS, a limited set of parameters which recreate the observed runout lengths and impact pressures of the investigated avalanches are validated. The study shows that RAMMS provides a helpful tool for reproducing runout lengths and avalanche impact pressures for Svalbard’s unique setting when calibrated using laser scanned avalanche data. With further work and a larger dataset, guidelines for friction parameters in RAMMS for use in hazard mapping, avalanche protection measures, and forecasting of avalanche hazard can be developed. i Samandrag Kvart år er snøskred observert nær, eller i Longyearbyen, den største tettstaden på Svalbard, og gjer ei kontinuerleg utvikling av risikohandtering, gjennom forskning og erfaring, høgst relevant. I denne oppgåva er fire snøskred frå vintersesongen 2015- 2016 undersøkt og kartlagt med terrestrisk laserskanning. Dataene frå dette, overflatemodellar med høg oppløysing, er bruka til validering av den to-dimensjonale numeriske snøskredmodellen RAMMS. Ved analyse av utløpssimuleringar i RAMMS er eit avgrensa sett parametrar som styrer utløpslengde av snøskred og skredtrykk mot konstruksjonar validert. Studien syner at RAMMS er eit nyttig verkty for å reprodusere utløpslengder av snøskred og skredtrykk mot konstruksjonar for det arktiske Svalbard. Med vidare arbeid og eit større datasett, kan ein utvikle retningsliner for friksjonsparametrar i RAMMS til bruk i risikokartlegging, vernetiltak mot snøskred og snøskredvarsling. ii Acknowledgements First I need to thank my dad, I definitely would not have gotten through this master thesis without his tireless help and support. The same goes for the rest of my family, who always support me and encourages me to follow my dreams. And Idun, it was so much fun to take a course together in Svalbard, I hope we can keep visiting each other in exotic places in the future! Many people have contributed to get me through my master thesis and the stay at UNIS and Svalbard, and I especially want to thank: Nina Aradottir for being an awesome flat mate, it is a pleasure living with you, and also for being a great partner in crime on our many late night Longyearbyen and Huset adventures, I know I can always count on you. Holt Hancock has provided great advices on the content of this master thesis, and thanks for the help with revision. Lise Gjellestad for help and support during the most frustrated parts of the process, both as a study advisor and friend, it’s good to know that your door is always open (for us). I would also like to thank all the other wonderful people at UNIS including Sarah, Lis, Monica, Linda, TK, Graham and all you other people who have made lunch breaks, coffee breaks and just life in general very enjoyable. I also need to thank my good friend Anne Jorunn who always reminds me how important it is to have fun, live life to the fullest, and that everything is possible with hard work. Thanks also to Jens Christensens legat for funding of fieldwork, and to my supervisors Alexander Prokop and Thomas Schuler. Lastly a thanks to the University of Oslo, who made it possible to do my whole master thesis at UNIS. iii Table of Contents 1. Introduction ................................................................................................................................................... 1 1.1 Motivation ............................................................................................................................................... 1 1.2 Avalanche history of Longyearbyen ............................................................................................. 2 1.3 Objectives and aim ............................................................................................................................... 6 2. Scientific background ................................................................................................................................. 7 2.1 Avalanche research in Svalbard ..................................................................................................... 7 2.2. Snow properties - an introduction to the Svalbard snowpack ......................................... 9 2.2.1. Temperature gradients .......................................................................................................... 10 2.2.2 Permafrost ................................................................................................................................... 10 2.3 Snow metamorphism ....................................................................................................................... 11 2.3.1 The curvature effect ................................................................................................................. 11 2.3.2 Equi-temperature (destructive) metamorphism ......................................................... 12 2.3.3 Kinetic-growth (constructive) metamorphism ............................................................ 12 2.3.4 Metamorphism of wet snow ................................................................................................. 13 2.4 Deformation in the snowpack ...................................................................................................... 14 2.5 Snow stratigraphy ............................................................................................................................. 16 2.6 Snowdrift and snow distribution in the terrain .................................................................... 17 2.7 Snow avalanches ................................................................................................................................ 19 2.8 Slab avalanches .................................................................................................................................. 20 2.9 Snow climate ....................................................................................................................................... 21 3. Regional background ............................................................................................................................... 24 3.1 Svalbard – geographical description ......................................................................................... 24 3.2 Svalbard’s climate and meteorology ......................................................................................... 26 3.2.1 Air temperatures ....................................................................................................................... 27 3.2.2 Precipitation ................................................................................................................................ 27 3.2.3 Wind and wind transportation of snow .......................................................................... 29 4. Methods ........................................................................................................................................................ 30 4.1 Fieldwork .............................................................................................................................................. 30 4.2 Measuring equipment: Terrestrial laser scanner................................................................. 32 4.2.1 Principles of laser scanning .................................................................................................. 33 4.2.2 Error sources with TLS ........................................................................................................... 35 4.2.3 Point cloud processing ............................................................................................................ 36 4.3 ArcGIS - ArcMap ................................................................................................................................. 36 4.4 Avalanche mapping and release area definition .................................................................. 37 iv 4.4.1 Structure from Motion (SfM) photogrammetry ........................................................... 37 4.4.2 Release area - Vindodden .....................................................................................................