LILLOOET RIVER CORRIDOR Submission of Final Report Our File713.002
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EngineeringStudyfor LillooetRiverCorridor FinalReport December2002 PembertonValleyDykingDistrict MountCurrieBand December 23, 2002 Mr. John Pattle, P.Eng. B.C. Ministry of Water, Land and Air Protection 10470 - 152nd Street Surrey, B.C. V3R 0Y3 Dear Mr. Pattle: RE: ENGINEERING STUDY FOR LILLOOET RIVER CORRIDOR Submission of Final Report Our File713.002 We are pleased to submit 3 copies of the Engineering Study for Lillooet River Corridor Final Report. This report presents current conditions and up-to-date hydraulic modelling results, with a backdrop of historical data and analysis of long-term geomorphological changes within the Pemberton Valley. This report will assist the Steering Group, and communities at large, in understanding and documenting the problem areas. Further, this report will form the foundation of a flood mitigation and management plan for the Pemberton Valley. We have very much enjoyed working on this project with you, and hope we can be of service to you again. We trust this is satisfactory. Yours truly, KERR WOOD LEIDAL ASSOCIATES LTD. Jonathon Ng, P.Eng., PMP Project Manager JN/am Encl. (3) P:\0700-0799\713-002\Report\TransLETTER.doc Engineering Study for Lillooet River Corridor Final Report December 2002 KWL File No. 713.002 ENGINEERING STUDY FOR LILLOOET RIVER CORRIDOR FINAL REPORT PEMBERTON VALLEY DYKING DISTRICT DECEMBER 2002 MOUNT CURRIE BAND STATEMENT OF LIMITATIONS This document has been prepared by Kerr Wood Leidal Associates Ltd. (KWL) for the exclusive use and benefit of the Mount Currie Band, the Pemberton Valley Dyking District, B.C. Ministry of Water, Land and Air Protection, Public Works and Government Services Canada, and Indian and Northern Affairs Canada. No other party is entitled to rely on any of the conclusions, data, opinions, or any other information contained in this document. This document represents KWL’s best professional judgement based on the information available at the time of its completion and as appropriate for the project scope of work. Services performed in developing the content of this document have been conducted in a manner consistent with that level and skill ordinarily exercised by members of the engineering profession currently practising under similar conditions. No warranty, expressed or implied, is made. COPYRIGHT NOTICE These materials (text, tables, figures and drawings included herein) are copyright of Kerr Wood Leidal Associates Limited (KWL). These materials may be reproduced for archiving and for distribution to third parties only as required to conduct business specifically relating river management activities on the Lillooet River. Any other use of these materials without the written permission of KWL is prohibited. KERR WOOD LEIDAL ASSOCIATES LTD. Consulting Engineers 713.002 ENGINEERING STUDY FOR LILLOOET RIVER CORRIDOR PEMBERTON VALLEY DYKING DISTRICT FINAL REPORT MOUNT CURRIE BAND DECEMBER 2002 CONTENTS EXECUTIVE SUMMARY ............................................................................i 1. INTRODUCTION.....................................................................................1-1 1.1 BACKGROUND....................................................................................................................1-1 STAKEHOLDERS .................................................................................................................1-1 NEED FOR STUDY...............................................................................................................1-1 1.2 STUDY OBJECTIVES ...........................................................................................................1-2 1.3 ENGINEERING WORK PROGRAM AND PROJECT DELIVERABLES ...........................................1-3 1.4 ENVIRONMENTAL ISSUES....................................................................................................1-3 1.5 PROJECT TEAM..................................................................................................................1-4 1.6 DEFINITIONS ......................................................................................................................1-4 DESIGN FLOOD ..................................................................................................................1-4 DESIGN FLOOD ELEVATION.................................................................................................1-4 FREEBOARD.......................................................................................................................1-5 DYKE DESIGN ELEVATION...................................................................................................1-5 2. STUDY AREA.........................................................................................2-1 2.1 LILLOOET RIVER WATERSHED ............................................................................................2-1 2.2 SETTLEMENT HISTORY OF THE PEMBERTON VALLEY ...........................................................2-1 2.3 BEDROCK GEOLOGY ..........................................................................................................2-3 2.4 GEOMORPHOLOGY AND SURFICIAL GEOLOGY .....................................................................2-4 3. PREVIOUS WORK .................................................................................3-1 3.1 ENGINEERING STUDIES AND WORKS ...................................................................................3-1 1946 TO 1952 ...................................................................................................................3-1 1953 TO 1978 ...................................................................................................................3-2 1979 TO 1985 ...................................................................................................................3-3 1985 TO 1990 ...................................................................................................................3-5 1988 HEC2 MODELS.........................................................................................................3-5 1990 TO PRESENT .............................................................................................................3-6 3.2 SCIENTIFIC STUDIES...........................................................................................................3-9 LILLOOET RIVER DELTA FORMATION....................................................................................3-9 SEDIMENT BUDGET FROM DELTA DEPOSITS ......................................................................3-10 MASS MOVEMENTS AND THEIR HYDROLOGIC LINK .............................................................3-11 4. WORK PROGRAM IMPLEMENTATION................................................4-1 4.1 FIELD WORK......................................................................................................................4-1 4.2 ANALYSIS ..........................................................................................................................4-4 4.3 STUDY PROCESS................................................................................................................4-5 5. FLUVIAL GEOMORPHOLOGY..............................................................5-1 5.1 MORPHOLOGICAL CHARACTERIZATION ...............................................................................5-2 5.2 CHANNEL CHANGES AND SEDIMENT TRANSPORT IN UPPER REACHES OF LILLOOET RIVER ...5-4 MORPHOLOGIC APPROACH TO SEDIMENT TRANSPORT.........................................................5-6 RESULTS ...........................................................................................................................5-9 CONCLUSIONS .................................................................................................................5-14 5.3 CHANNEL CHANGES AND SEDIMENT TRANSPORT IN LOWER REACHES OF LILLOOET RIVER 5-14 CHANNEL ADJUSTMENTS TO 1946-1953 ENGINEERING WORKS .........................................5-15 CROSS SECTIONAL CHANGES ...........................................................................................5-21 SEDIMENT TRANSPORT.....................................................................................................5-22 KERR WOOD LEIDAL ASSOCIATES LTD. i Consulting Engineers 713.002 ENGINEERING STUDY FOR LILLOOET RIVER CORRIDOR PEMBERTON VALLEY DYKING DISTRICT FINAL REPORT MOUNT CURRIE BAND DECEMBER 2002 CONCLUSIONS .................................................................................................................5-26 5.4 BANK EROSION................................................................................................................5-27 LILLOOET RIVER...............................................................................................................5-27 GREEN RIVER ..................................................................................................................5-32 BIRKENHEAD RIVER..........................................................................................................5-33 RYAN RIVER AND MILLER CREEK ......................................................................................5-34 5.5 DELTA FORMATION ..........................................................................................................5-34 6. CLIMATE AND HYDROLOGY ...............................................................6-1 6.1 BACKGROUND AND HISTORICAL ANALYSIS .........................................................................6-1 6.2