Experimental investigation and numerical modelling of under cover ice transport and hanging dam formation processes
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Abstract
Under cover ice transport and hanging dam formation are river ice processes that have a significant impact on hydraulics of an ice covered river during the winter. A thick ice accumulation from a hanging dam can cause the water level to rise imposing flooding to nearby communities, and hydropower generation during the winter is often negatively impacted by hanging dams. Under cover ice transport and hanging dam formation processes are not yet well understood due to difficulties associated with obtaining field data and lack of numerical modelling efforts. This research investigates under cover ice transport and hanging dam formation processes using laboratory experiments and numerical modelling. Under cover ice transport laboratory experiments were conducted to further develop a cover load transport formula describing the relationship between dimensionless transport rate and dimensionless flow strength under equilibrium conditions and this formula is known to be the only cover load formula that is developed exclusively using simulated ice that has similar physical properties to ice in a natural river. The effect of approach Froude number in the river and the incoming ice supply rate on hanging dam formation was analyzed using a series of experiments in a scaled down physical model. This is the first study of its kind that presents the relationship between the approach Froude number and the incoming ice supply rate on hanging dam formation and evolution, contributing to improving our understanding of these processes. The current model formulation for under cover transport processes and hanging dam formation in the CRISSP2D numerical model was evaluated and the laboratory developed cover load transport formula was incorporated in the model to improve the model in this application.