Author(s): James L. Wuebben
Linked Author(s): James Wuebben
Keywords: No Keywords
Abstract: The formation of an ice cover on an alluvial system results in significant changes in the flow regime due to the interaction between the ice cover, fluid flow, fluid properties, sediment and bedforms. For the case of uniform flow in a rigid channel, the addition of an ice cover of uniform thickness and surface roughness would typically result in an increase in water depth and a reduction in water velocity and bed shear. Such a flow can be conceptually split along a hypothetical plane of zero shear located approximately at the point of maximum velocity in any vertical profile. If this concept could be extended to flow over a movable bed, then existing free surface sediment transport theory could be applied to the lower layer by treating it as a distinct "open channel" case. To test the practicability of using this lower layer approach to predict sediment transport and resistance to flow in an ice covered channel, a series of tests were conducted at various discharges in a laboratory flume. The sediment was a uniform, 45-mm diameter quartz sand and bedforms were in the ripple and dune regimes. For each discharge, a run was initiated by establishing uniform flow under a simulated ice cover. Once the lower layer depth and discharge were determined, a corresponding open water flow was established leaving other parameters unchanged. The ice covered and free surface flows were then compared based on sediment discharge, bed form geometry, and energy slope to determine the applicability of the lower layer approach.
Year: 1988