RIVER ICE INFLUENCES ON FORT PECK REACH, MISSOURI RIVER
iii
CONTENTS
Preface ..................................................................................................................ii
1
INTRODUCTION .......................................................................................... 1
Objectives ....................................................................................................... 1
Significance .................................................................................................... 3
Background .................................................................................................... 3
2
PHYSICAL SETTING OF THE FORT PECK REACH ............................... 5
Channel morphology ....................................................................................... 5
Bed sediment ................................................................................................... 6
Riverbanks ...................................................................................................... 9
Flow characteristics ...................................................................................... 10
Ice formation ................................................................................................ 14
3
REVIEW OF RIVER ICE INFLUENCES ON
CHANNEL MORPHOLOGY ............................................................... 15
Factors affecting river ice ............................................................................. 15
Ice cover influence on the local cross section of flow .................................. 17
Channel anabranching and avulsion ............................................................. 19
Cover influence on thalweg alignment ......................................................... 19
Ice cover influence on channel bed elevation ............................................... 22
4
REVIEW OF RIVER ICE INFLUENCES ON RIVERBANKS ................. 24
Influence on soil pore pressures ................................................................... 24
Thermal influences on riverbank strength .................................................... 25
Bankfast ice loading of riverbanks ............................................................... 26
Gouging and abrasion of riverbanks ............................................................ 27
5
SURVEY PROGRAM ................................................................................. 29
Survey personnel .......................................................................................... 29
Survey sites .................................................................................................. 29
Survey schedule ............................................................................................ 31
Specific issues for survey sites ..................................................................... 33
Features of survey sites ................................................................................ 33
Summary of measurements and observations .............................................. 41
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