Author(s): S. Beltaos
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Keywords: No Keywords
Abstract: Ice breakup is an important event in the regime of northern rivers mainly due to ice jamming and associated problems, e. g., flooding, forces on structures and erosion. Breakup is triggered by mild weather and the attendant increases in runoff and heat input to the ice. At present, the onset of breakup can only be forecast empirically, using site-specific historical records. Recent work has produced partial understanding of the early phases of breakup (formation of hinge and transverse cracks, first movement of the ice) but more observational data are needed for a complete model of breakup initiation. When set in motion, the ice quickly breaks down into small fragments and ice jams begin to form. Subsequent developments are highly disorderly owing to the multitude of factors that are at work, e. g., hydrologic, geomorphic, structural. Present understanding of ice jam initiation and evolution is poor and theoretical jam models have to date focused on equilibrium conditions. Their practical utility is thus restricted to forecasting potential high water levels that may or may not be realized during breakup. Progress in this regard requires consideration of the breakability of the ice cover and its effects on jam formation and release.
Year: 1984