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LID SWM Planning and Design Guide β

Flow in a swale

Revision as of 17:26, 3 July 2019 by Jenny Hill (talk | contribs)

Swale sections.PNG Flow (Q) in an open channel, such as a swale, may be calculated using Manning's equation\[Q=VA=\frac{R^{\frac{2}{3}}S^{\frac{1}{2}}}{n}\] Where\[R=\frac{A}{P}\]


  • Q = the flow in the swale (m3/s)
  • A = the cross sectional area of the swale (m2)
  • P = the wetted perimeter of the swale (m)
  • S = the longitudinal slope (m/m)
  • n = Manning's coefficient (dimensionless)