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Title: Effective hydraulic roughness for channels having bed roughness different from bank roughness : a state-of-the-art report
Authors: Cox, Robert George
Keywords: Flow resistance
Hydraulic roughness
Manning formula
Open channel flow
Roughness coefficient
Frictional resistance
Publisher: Hydraulics Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Series/Report no.: Miscellaneous paper (U.S. Army Engineer Waterways Experiment Station) ; H-73-2.
Description: Miscellaneous Paper
Abstract: This report summarizes two numerical studies, one laboratory experimental study, and one analytical study of flow resistance in rectangular channels having one type or degree of boundary roughness on the bed and a second type or degree of roughness on the sidewalls. The numerical study showed that usual procedures for estimating resistance coefficients for channels of this type are not adequate. The laboratory study indicated that the relations between the effective Manning's η, the sidewall Manning's η, the bed Manning's η, and the channel geometry could be established empirically by extensive laboratory testing. The analytical study proved that laboratory studies using a smooth surface for one of its boundaries had little application to practical design problems. It also showed that the best solution to the problem probably would result by use of hydraulic roughness values to describe the boundary surfaces. The study showed that relatively large errors in estimating the hydraulic roughness effect only minor errors in capacity design.
Rights: Approved for public release; distribution is unlimited.
Appears in Collections:Miscellaneous Paper

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