This investigation was to improve the design of rock lined channels. By an extensive review of the literature it became apparent that there exist important functional relationships between Manning's n and the Froude number, Reynolds number, relative roughness, and slope. To establish these relationships, over one hundred independent field and laboratory data-sets were subjected to statistical analysis. Results revealed that for rough channels n is influenced by the Froude number and the slope. In smooth channels (y > 6 D sub 50) n is primarily controlled by the Reynolds number. Based on these results the selection of the proper roughness factor n for drainage channels lined with larger rocks may be aided by the relationship n = 0.38 (S to the 0.57th power)/F where S is the channel slope and F is the Froude number of the flow. This formula is for the initial determination of the magnitude of n. As a consequence of these results, the maximum Manning's n for large channels specified in the ODOT Location and Design Manual was recommended to be changed from n = 0.06 to n = 0.04. (Author)

  • Corporate Authors:

    University of Akron

    Department of Civil Engineering
    Akron, OH  United States  44325-3905

    Ohio Department of Transportation

    P.O. Box 889
    Columbus, OH  United States  43215

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
  • Authors:
    • Simon, A L
    • Sarikelle, S
  • Publication Date: 1980-7-1

Media Info

  • Features: Figures; References; Tables;
  • Pagination: 47 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00334673
  • Record Type: Publication
  • Report/Paper Numbers: FHWA/OH-80/007 Final Rpt.
  • Contract Numbers: St Job No. 14310(0)
  • Created Date: Sep 16 1981 12:00AM