River ice breakup flood forecasting

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River ice breakup can be instigated by spring runoff, mid-winter thaws, and hydro-peaking operations, and is a crucial event on Canadian rivers because of its economic and ecological impacts. The breakup period features frequent ice jam events which can result in severe and hard-to-predict flooding; further, when formed in place, ice jams can create physical barriers that impede navigation. When ice jams release, they can produce destructive high-speed water waves and ice runs that can damage infrastructure, cause bank and bed erosion, and endanger or even sink shipping. Because of the risks posed by ice jams, hydro-peaking operations often need to be modified to avoid triggering their formation and release, thus limiting hydro-power production. Ice jam events may adversely impact river ecosystems but in some cases can also provide essential replenishment to the river systems (e.g. Mackenzie River Delta). For all these reasons, it is therefore desirable to understand river breakup and ice jam phenomena and to be able to predict their occurrence with greater accuracy. The challenge is that the presence of ice, interacting with the dynamic flow in various ways, makes forecasting these events very difficult. ***This research program aims to address several key issues that are currently impeding our ability to forecast ice jam floods during river ice breakup, and will advance our knowledge of complex breakup processes. Mathematical modelling techniques will be used, complemented with existing field data. First, the effects of major factors that affect the timing, frequency, and severity of river breakup and associated ice jam events will be investigated, including ice conditions, channel morphology, meteorological conditions, and flow conditions. Second, new model will be developed. Particularly for multi-channel systems such as river delta areas, where ice jamming tends to occur, existing models are not operationally viable. One-dimensional models only simulate single channel flows, and it is not practical to measure or model an extended reach in two dimensions. The model developed in this research will therefore provide a unique operational tool that allows investigation of various problems caused by ice jamming in multi-channel systems. The research will also provide a forecasting model that is operationally practical and can reliably predict the anticipated severity of ice jam flooding. Such a model will allow earlier predictions of flooding and hence permit speedier evacuation of affected communities, which will immediately benefit northern communities situated next to rivers that experience ice jam flooding. Overall, the proposed program will produce a more accurate and comprehensive river ice model and move us towards the ultimate goals of reliable prediction of ice jam formation and release events in natural rivers and improved projections of flood risk in advance of river breakup.**