Manning Formula—A Misnomer?

by Garnett P. Williams, Res. Hydro.; Water Resour. Div., U.S. Geological Survey, Washington, DC,

Serial Information: Journal of the Hydraulics Division, 1970, Vol. 96, Issue 1, Pg. 193-200

Document Type: Journal Paper


No one ever proposed the popular Manning formula in the form commonly used today. At least ten papers, beginning with that of Gauckler in 1867, offered a monomial equation giving V as a function of R2/3 S1/2 for certain flow conditions. Manning's paper, 1891, was the fifth, chronologically, in this group of papers. The Frenchman Flamant is primarily responsible for first attributing the formula to Manning and for introducing the resistance coefficient n. H. T. Bovey is known to have been, in 1901, the first to write the equation in the form used today for English units. The expression Manning's n first crept into the literature in 1916 and represented a rather ironic development, as Manning had clearly rejected the use of the coefficient n.

Subject Headings: Load and resistance factor design

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