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<br />e <br /> <br />e <br /> <br />e <br /> <br />cross sections. With respect to the frequency of bottomland inundation, channel narrowing can <br />have a positive impact since it reduces the channel conveyance capacity. A reduction in <br />conveyance lowers the discharge at which flooding is initiated. However, channel narrowing <br />may enhance channel scour at high flows through increased bed shear and sediment transport for <br />a given discharge. This would increase channel conveyance. Therefore, the influence of <br />channel narrowing on flood inundation frequency may vary. <br /> <br />Conclusions Concerning Observed Channel Response During 1995 Runoff <br /> <br />Often, in canyon river systems, a sand wave extending several miles in the form of sand <br />bars, filled-in thalwegs and side channels or just an increase in bed elevation, can accumulate in <br />a channel reach. This sand wave moves in a downstream direction principally as bed load. Both <br />of the study reaches experienced some net fill in the cross sections surveyed during the 1995 <br />runoff season. The channel geometry adjusted to the variable sediment load with thalweg shifts <br />from one side of the river to the other, sand bar development, thalweg scour to bedrock, and <br />through variation in the cross section geometry. The cross sections will continue to adjust <br />through the base flow season by filling the scour holes, attacking the sand bar deposits and <br />redistributing the sand more uniformly in the channel. <br /> <br />28 <br />