Floods in the Ölfusá Basin, Iceland: a Geographic Contribution to the Assessment of Flood Hazard and Management of Flood Risk
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Floods in the Ölfusá basin, Iceland: A geographic contribution to the assessment of flood hazard and management of flood risk Emmanuel Pagneux Faculty of Life and Environmental Sciences University of Iceland 2011 Floods in the Ölfusá basin, Iceland: A geographic contribution to the assessment of flood hazard and management of flood risk Emmanuel Pagneux Thesis submitted for the degree of Philosophiæ Doctor in Geography Supervisors Dr. Guðrún Gísladóttir Faculty of Life and Environmental Sciences University of Iceland Dr. Árni Snorrason Icelandic Meteorological Office Salvör Jónsdóttir, M.Sc. Reykjavík University Doctoral Committee Dr. Guðrún Gísladóttir Faculty of Life and Environmental Sciences University of Iceland Dr. Árni Snorrason Icelandic Meteorological Office Salvör Jónsdóttir, M.Sc. Reykjavík University Opponents Dr. Sally Priest Flood Hazard Research Centre, Middlesex University Dr. Christophe Cudennec Agrocampus Ouest, French National Institute for Agricultural Research Faculty of Life and Environmental Sciences School of Engineering and Natural Sciences University of Iceland Reykjavík, October 2011 Floods in the Ölfusá basin, Iceland: A geographic contribution to the assessment of flood hazard and management of flood risk A thesis submitted for the degree of Philosophiae Doctor in Geography Copyright © 2011 Emmanuel Pagneux All right reserved Faculty of Life and Environmental Sciences School of Engineering and Natural Sciences University of Iceland Askja, Sturlugata 7 IS-101 Reykjavík Iceland Telephone: +354 525 4000 Bibliographic information: Pagneux, E., 2011, Floods in the Ölfusá basin, Iceland: A geographic contribution to the assessment of flood hazard and management of flood risk, PhD dissertation, Faculty of Life and Environmental Sciences, University of Iceland, 94pp. ISBN 978-9979-9967-9-8 Printed by Pixel prentþjónusta Reykjavík, October 2011 Contents Abstract ............................................................................................................................... ix Ágrip ..................................................................................................................................... x Acknowledgements ............................................................................................................. xi 1 Introduction ..................................................................................................................... 1 1.1 Background ............................................................................................................................ 1 1.2 Aims of the research ............................................................................................................. 2 1.3 Regional settings ................................................................................................................... 3 1.4 Methods and results .............................................................................................................. 7 1.4.1 Paper I ......................................................................................................................... 7 1.4.2 Paper II ........................................................................................................................ 7 1.4.3 Paper III ....................................................................................................................... 8 1.4.4 Paper IV ....................................................................................................................... 9 1.5 Perspectives......................................................................................................................... 10 1.5.1 Impact of the research .............................................................................................. 10 1.5.2 Future work ............................................................................................................... 10 1.6 Conclusion ........................................................................................................................... 11 2 Inundation extent as a key parameter for assessing the magnitude and return period of flooding events in southern Iceland ................................................................. 15 2.1 Introduction ......................................................................................................................... 15 2.2 Study area ............................................................................................................................ 17 2.3 Methodology ....................................................................................................................... 19 2.3.1 Flood census, seasonality and triggers ..................................................................... 20 2.3.2 Ice jamming sites and flooding path identification ................................................... 21 2.3.3 Flooding boundaries and extent computation ......................................................... 21 2.3.4 Extent computation, floodplain, and inundation likelihood ..................................... 22 2.4 Results ................................................................................................................................. 22 2.4.1 Flooding census, seasonality and triggers................................................................. 22 2.4.2 Ice jamming sites and flooding path ......................................................................... 23 2.4.3 Flood plain, magnitude ranking, and likelihood of flooding ..................................... 25 2.5 Discussion ............................................................................................................................ 26 2.5.1 Reliability of data sources ......................................................................................... 26 2.5.2 Seasonality and triggers ............................................................................................ 26 2.5.3 Flood plain and extent of inundations ...................................................................... 27 2.5.4 Susceptibility to inundation ...................................................................................... 28 2.5.5 Perspectives .............................................................................................................. 28 2.6 Conclusion ........................................................................................................................... 29 3 High-accuracy mapping of inundations induced by ice jams: a case study from Iceland ................................................................................................................................ 33 3.1 Introduction ......................................................................................................................... 33 3.2 Study area ............................................................................................................................ 36 3.3 Methodology ....................................................................................................................... 38 3.3.1 Data production and calculation ............................................................................... 38 3.3.2 Product delivery ........................................................................................................ 39 3.4 Results and discussion ......................................................................................................... 40 3.5 Conclusion ........................................................................................................................... 43 vii 4 Public perception of flood hazard and flood risk in Iceland: a case study in a watershed prone to ice-jam floods ................................................................................... 47 4.1 Introduction ......................................................................................................................... 47 4.2 Study area ............................................................................................................................ 49 4.2.1 Flood hazard .............................................................................................................. 49 4.2.2 Other natural hazards ............................................................................................... 49 4.2.3 Flood risk management ............................................................................................. 50 4.3 Methodology ....................................................................................................................... 52 4.3.1 Descriptive variables ................................................................................................. 53 4.3.2 Explanatory variables ................................................................................................ 54 4.4 Results ................................................................................................................................. 56 4.4.1 Awareness ................................................................................................................. 56 4.4.2 Risk estimation and worry ......................................................................................... 59 4.5 Discussion ............................................................................................................................ 60 4.5.1 Experience and time .................................................................................................