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River ice jams are a common occurrence on northern rivers, and their formation can present a severe flood risk to nearby communities. As more and more river regulation projects are developed to provide an alternative to fossil fuels for electrical power-generating capacity, our need to understand the mechanisms associated with ice jam formation under variable flow conditions becomes more vital. This is because, at present, hydropeaking operations are often severely curtailed during the ice-affected seasons due to concerns that sudden flow fluctuations might instigate ice jams and associated flooding. Here, an experimental investigation explores the effects of rapid increases in discharge on ice jam formation and evolution. It is found that the thickness of ice jams formed under highly dynamic flow conditions tend to be slightly thinner than those formed during steady carrier flows for comparable discharges. Also, despite the highly dynamic nature of these consolidation events, the resulting ice thicknesses appear reasonably well approximated by steady flow theory. [ABSTRACT FROM AUTHOR]

Ice jams pose a significant threat to human safety and property and represent one of the most dynamic of river ice processes. A key limitation in the advancement of knowledge of ice jam formation is the lack of quantitative data describing these dynamics, which is essential also for validation of advanced computational models. In this study, an experimental investigation of ice jam formation under steady carrier discharge was undertaken. Thus, unsteady effects were entirely due to the ice jam formation process itself. Quantitative data describing the variation in discharge, ice jam thickness, water level variation, and ice cover progression provides unprecedented data describing the dynamics of ice jam formation. While the processes of ice jam formation are indeed dynamic, the results of this investigation suggest that the analysis of ice jams formed under steady carrier flow conditions may be adequately handled by the usual steady flow ice jam stability relationships. The applicability of the popularly applied wide jam theory approach to modeling ice jams is further supported by this investigation. [ABSTRACT FROM AUTHOR]