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ERDC/CRREL TR-02-14
Eq 35, though entailing simplifying assumptions, lead to a clear result. As
the covered flow depth Yi usually exceeds the open water depth Yo, the ratio Sio/So
is less than 1. Therefore, the energy gradient (and stream power) available for
sediment transport and channel forming decreases when a channel has a free-
floating ice cover. For a typical value of, say, Yo/Yi ≈ 0.8, Sio/So ≈ 0.5; in other
words, for a given flow rate in a channel of given length, approximately half the
energy expenditure is available for sediment transport and channel forming. The
effect of an ice cover, therefore, is to trigger a shift in thalweg sinuosity and
alignment so as to balance flow-energy availability and use. Figure 11 suggests,
for instance, that halving the slope of a meandering channel (say, from 0.008% to
0.004%) will reduce thalweg sinuosity; i.e., the thalweg attempts to straighten