RIVER ICE INFLUENCES ON FORT PECK REACH, MISSOURI RIVER
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Bank
Bar
Point
Bar
Open Water Flow
Main
Thalweg
Ice-covered Flow
Figure 13. River ice impact on the thalweg of a
sinuous-braided channel. An ice cover causes the
main thalweg to become more sinuous.
with all its repercussions for local channel slope and morphology. When Qsc is
less than Qs, the bed elevation must rise locally. Conversely, if Qsc is greater than
Qs, the bed elevation must drop locally. The former condition usually would
prevail for a free-floating cover, because the bulk velocity of the flow decreases.
The latter condition may occur beneath an ice jam (Wuebben 1988, Neill 1976)
or when the cover is fixed and rigid, because the bulk velocity of the flow is
forced to increase substantially under the ice.
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