Author(s): S. Beltaos
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Keywords: No Keywords
Abstract: The results of recent field observations on river ice jams during breakup are presented and analyzed. These observations include visual documentation, jam stage profiles and hydrometric surveys of the pertinent river reaches. Two theoretical models of floating river ice jams, developed previously by others, are discussed briefly and compared. It is shown that the two theories give similar expressions for the equilibrium thickness of jams formed by internal collapse. Use of these expressions for engineering predictions of high water stages due to such jams requires information regarding the resistance to flow caused by the underside of the cover, the shear strength of the cover and hydraulic characteristics of the study reach. The latter can be obtained by means of hydrometric surveys. Available field data on the former aspects are scarce. Direct analysis of the present data is not possible due to a lack of jam thickness measurements. Instead, the results are analyzed indirectly, by evaluating the jam thickness from flow resistance considerations. Despite the many approximations, the consistency of the various parameters evaluated by the present analysis supports the procedure outlined herein. The internal friction coefficient for the fragmented cover, which governs the thickness of ice jams, was found to be in fair agreement with a value suggested earlier by others.
Year: 1978