Spatial and Temporal Variations of River-ice Break-up, Mackenzie River Basin, Canada by Laurent Paul de Rham B.Sc., University of Victoria, 2003 A Thesis Submitted in Partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCE in the Department of Geography Laurent Paul de Rham, 2006 University of Victoria All rights reserved. This thesis may not be reproduced in whole or in part, by photocopy or other means, without the permission of the author. ii Spatial and Temporal Variations of River-ice Break-up, Mackenzie River Basin, Canada by Laurent Paul de Rham B.Sc., University of Victoria, 2003 Supervisory Committee Dr. T.D. Prowse (Department of Geography) ________________________________________________________________________ Supervisor Dr. B.R. Bonsal (Department of Geography) ________________________________________________________________________ Departmental Member Dr. I.J. Walker (Department of Geography) ________________________________________________________________________ Departmental Member Dr. S. Boon (Geography Program, University of Northern British Columbia) ________________________________________________________________________ Outside Member iii Dr. T.D. Prowse (Department of Geography) Supervisor Dr. B.R. Bonsal (Department of Geography) Departmental Member Dr. I.J. Walker (Department of Geography) Departmental Member Dr. S. Boon (Geography Program, University of Northern British Columbia) Outside Member Abstract Hydrological data extracted directly from Water Survey of Canada archives covering the 1913-2002 time period is used to assess river ice break-up in the Mackenzie River basin. A return-period analysis indicates that 13 (14) of 28 sites in the basin are dominated by peak water-levels occurring during the spring break-up (open-water) period. One location has a mixed signal. A map of flooding regimes is discussed in terms of physical, hydrological and climatic controls. Annual break-up is found to progress from south to north, over a period representing ~¼ of the year. Average annual duration is ~8 weeks. The at site break-up period, recognized as the most dynamic time of the year on cold-regions river systems is found to last from 4 days to 4 weeks. Break-up timing (1966-1995) is found to be occurring earlier in the western portions of the basin (~3 days/decade), concurrent with late 20th century warming. iv Table of Contents Abstract..............................................................................................................................iii Table of Contents...............................................................................................................iv Acknowledgments.............................................................................................................. vi CHAPTER 1: INTRODUCTION....................................................................................... 1 1. INTRODUCTION ...................................................................................................... 1 2. RESEARCH UNKNOWNS ....................................................................................... 1 3. DATA SOURCE......................................................................................................... 4 4. STUDY AREA ........................................................................................................... 4 5. SPECIFIC OBJECTIVES........................................................................................... 5 REFERENCES ............................................................................................................... 7 CHAPTER 2: ASSESSMENT OF ANNUAL HIGH-WATER EVENTS FOR THE MACKENZIE RIVER BASIN, CANADA...................................................................... 10 ABSTRACT.................................................................................................................. 10 1. INTRODUCTION ................................................................................................... 12 2. STUDY AREA ......................................................................................................... 14 3. BACKGROUND: COLD-REGIONS FLOW REGIME.......................................... 16 4. DATA SOURCE AND METHODOLOGY............................................................. 17 4.1. Station Selection ................................................................................................ 17 4.2. Data Extraction Procedures................................................................................ 18 4.2.1. Maximum Annual Instantaneous Break-up (HM) and Open (HO) Water- level....................................................................................................................... 18 4.3. Return-period Assessment ................................................................................. 20 4.3.1. Return-period Analyses .............................................................................. 20 4.4. Regime Classification ........................................................................................ 21 4.4.1. Dominant Regime Classification ................................................................ 21 4.4.2. Classification of Return-Period Line Patterns ............................................ 21 4.4.3. Exceedence of 2.33 year Open-Water Event .............................................. 22 4.4.4. Difference in Magnitude between the 2 and 10-Year HM’ and HO’ ........... 23 4.5. Stage-discharge Classification........................................................................... 23 4.6. Regime Map and Physical Characteristics......................................................... 23 4.7. Data Assumptions and Limitations.................................................................... 24 5. RESULTS AND DISCUSSION............................................................................... 25 5.1. Regime Classification ........................................................................................ 25 5.1.1. Dominant Regime Classification ................................................................ 25 5.1.2. Classification of Return-Period Line Patterns ............................................ 26 5.1.3. Exceedence of 2.33 year Open-Water Event .............................................. 28 5.1.4. Difference in Magnitude between the 2 and 10-Year HM’ and HO’ ........... 29 5.2. Stage-Discharge Classification .......................................................................... 30 5.3. Regime Map and Physical Characteristics......................................................... 31 5.3.1. Basin Area................................................................................................... 32 5.3.2. Elevation ..................................................................................................... 33 5.3.3. Stream Order............................................................................................... 34 v 5.3.4. Channel Slope ............................................................................................. 35 5.3.5. Flow Direction ............................................................................................ 35 5.3.6. Other Factors............................................................................................... 36 6. CONCLUSIONS AND FUTURE RECOMMENDATIONS................................... 37 REFERENCES ............................................................................................................. 41 LIST OF TABLES........................................................................................................ 47 LIST OF FIGURES ...................................................................................................... 48 CHAPTER 3: TEMPORAL VARIATIONS IN RIVER-ICE BREAK-UP: THE MACKENZIE RIVER, CANADA................................................................................... 60 ABSTRACT.................................................................................................................. 60 1. INTRODUCTION .................................................................................................... 62 2. CLIMATIC TRENDS AND RIVER-ICE BREAK-UP ........................................... 63 3. STUDY AREA ......................................................................................................... 66 4. ICE BREAK-UP PROCESSES ................................................................................ 67 5. DATA SOURCE AND METHODOLOGY............................................................. 68 5.1. Data and Station Selection................................................................................. 68 5.2. Data Extraction and Analysis............................................................................. 69 5.2.1. Spring Break-up Event Variables ............................................................... 69 5.2.2. Spring Break-up Duration Variables .......................................................... 71 5.2.3. General Statistics ........................................................................................ 72 5.2.4. Isochrone Mapping ..................................................................................... 72 5.2.5. Last ‘B’ Date Assessment........................................................................... 73 5.2.6. Trend Analysis............................................................................................ 73 5.3. Data Assumptions