Author(s): Brennan T. Smith; Robert Ettema
Keywords: No Keywords
Abstract: The hydraulics of alluvial rivers in less-temperate parts of the World may be complicated by the presence of ice covers. Such covers may persist for several days to several months and can vary in roughness from the smooth underside of a newly formed cover to the jagged outcrop pings of a broken cover. Because the cover drastically alters the boundary conditions of a channel flow, one can expect changes in the internal structure of the flow. These changes are manifested as modifications to the resistance, sediment transport and bedform relations for a river. The goal of the experiments reported herein is to discover how the structure of the flow field over alluvial dunes is altered by ice-cover presence and ice-cover roughness. To this end, covered and free-surface flows over a fixed train of dunes in a laboratory flume have been mapped using Laser-Doppler Velocimetry (LDV). The results of these experiments, coupled with earlier results of experiments on similar loose-bed flows, are intended to provide an improved model of ice-covered flow and sediment transport.