Flow-sediment interactions in complex three-dimensional curvilinear river flows

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Sound management of rivers in Canada and worldwide is essential for many important purposes, including minimization of flood hazard, production of hydroelectricity, protection of in-stream and stream-bank infrastructure, and maintenance of healthy fisheries and aquatic ecosystems. River management is challenging because rivers move sediment, and this transfer of sediment determines the shape of the river itself. River morphology can change due to natural and human influences, yet prediction of changes in channel form remains a challenging task. The proposed research program includes three projects designed to elucidate the relations between three-dimensional turbulent flow and sediment particle entrainment and transport in rivers, in order to understand and predict river morphology and habitat. Research is to be conducted in the field, the laboratory, and numerically. The first project describes sediment-flow processes throughout a large reach of the wandering gravel-bed Fraser River, British Columbia. The second project examines the complex three-dimensional turbulent flow field and associated sediment transport through a series of submerged groynes in a channel bend. Submerged groynes are used to protect eroding river banks while providing habitat for stream organisms. The third project will be a study of semi-alluvial rivers, which in this case are rivers dominated by glacial deposits. Such rivers are common in Canada, but poorly understood. In all three projects, high resolution spatially distributed measurements of the turbulent forcing flow and associated sediment transport will be utilized to construct improved morphodynamic models of river channel change. These models will serve as valuable tools for practicing engineers faced with managing and restoring the nation's rivers.