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Measuring the flow resistance of submerged grass
Author(s) -
Wilson C. A. M. E.,
Horritt M. S.
Publication year - 2002
Publication title -
hydrological processes
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.222
H-Index - 161
eISSN - 1099-1085
pISSN - 0885-6087
DOI - 10.1002/hyp.1049
Subject(s) - flume , flow resistance , drag , flow (mathematics) , open channel flow , vegetation (pathology) , hydrology (agriculture) , numerical models , mathematics , environmental science , geology , numerical analysis , geotechnical engineering , computer simulation , mechanics , statistics , geometry , physics , mathematical analysis , medicine , pathology
Through laboratory experiments conducted in a grass‐lined flume, the hydraulic resistance of grass is measured and quantified. For the grass examined, it is found that Manning's n value is greater than those recommended in well‐established texts such as Chow (1959. Open Channel Flow . McGraw‐Hill: Singapore), relatively lower than those predicted by n ‐ UR methods, but corresponds well with the value found from calibration studies of two‐ and three‐dimensional numerical models. The assumption of a uniform Manning's n value with flow depth, which is often made in numerical modelling, may be invalid depending on the relative submergence of the vegetation. Drag coefficients are evaluated for a method applicable to three‐dimensional numerical models. Further detailed experimental investigation and application of these approaches within a numerical modelling framework is now recommended. Copyright © 2002 John Wiley & Sons, Ltd.