Author(s): Kersi S. Davar; Ian M. Macgougan
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Keywords: No Keywords
Abstract: The analysis of resistance of natural streams during winter is complicated by the presence of an ice cover which forms an additional boundary with complex undersurface configurations varying over time. The roughness characteristics are difficult to directly measure in-situ. Indirect estimates of the effective height of boundary roughness have been suggested by Larsen and others based on the Karman-Prandtl relation for fully turbulent flows over a rough boundary. A field program was set up for a 365 m nearly straight reach of the Nashwaak River, New Brunswick. The results were encouraging but some limitations were encountered. The method was extended to ice-covered conditions to estimate k for the ice undersurface and Several equations, described later, were introduced to calculate resistance coefficients which were compared to actual resistance coefficients obtained from measurements of discharge, area, hydraulic radius, and slope of the energy line for the reach. The results are presented and discussed. The conclusions indicate that the method is feasible for small orders of roughness, but is not applicable for large irregular roughnesses. Guide criteria need to be developed for the limits of applicability of this approach.
Year: 1984