Influence of Ice Processes on fluvial sediment transport

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The proposed research will measure and model the influence of river ice processes on sediment transport. Knowledge of sediment transport is required for prediction of changes to river morphology and habitat, due to climate change, changes in land-use, and/or river development. However, little is known about sediment transport in the presence of river ice. In particular, very few studies have assessed sediment transport during spring break-up of river ice, when sediment transport can be most intense. Winter ice covers most Canadian rivers, but the lack of understanding of influence of ice processes on sediment transport impedes ability to predict morphological and habitat change in Canadian rivers. The case study for the proposed research will be the Lower Nelson River (LNR). The supporting organizations of the research are Manitoba Hydro and Hatch Ltd, which have measured sediment transport (suspended load and bed load) in the LNR since 2005, but almost no measurements have been taken in winter months when an ice cover and ice processes can affect sediment transport. The proposed work includes two years of data collection and subsequent development of improved numerical models. In the first year Acoustic Doppler Current Profiler (ADCP) velocity profile and suspended sediment samples will be taken through holes cut in the ice-cover at feasible LNR locations. The ADCP acoustic backscatter intensity will be correlated with measured suspended sediment concentrations, such that a local calibration curve is developed for ADCP measurement of suspended sediment concentration. In the second year, at two river locations, continuous time series of up-looking ADCP and ice profiler measurements will be taken, including the periods of ice-cover formation and break-up. These will be the world's first continuous measurements of sediment transport during ice break-up, when sediment transport is expected to be the most intense. These data sets will be used to further develop and validate both physically-based and data-driven models of river ice and sediment transport processes. The resulting models will be valuable for evaluating the influence of ice on sediment transport processes in rivers throughout Canada.