Author(s): Henry S. Santeford; George R. Alger; Michelle Irmen-Christensen
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Keywords: No Keywords
Abstract: The freeze-up of rivers is often envisioned as the upstream progression of stalled ice floes. Although this process may be a major factor in the formation of an ice cover on large rivers, it is not the only process by which an ice cover develops on small rivers. Four distinctly different processes have been identified and are described in detail. They include: (1) rapid black ice formation in low velocity flow (less than 0.5 ft/sec or 0.15 m/sec); (2) a true choked condition resulting from anchor ice deposits; (3) the conventional growth by juxtaposition; and (4) slow outward progression of shorefast ice. Detailed field measurements of each type have been made. The data suggest that although in each case a limiting Froude number is met, it is not possible to distinguish the freezing mechanism by use of a limiting Froude number. A dimensionless parameter, the regime coefficient, defined as the square root of energy slope divided by roughness coefficient is proposed as an alternative. The results appear promising with the limited data.
Year: 1986