Difference between revisions of "Retention swales"

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<math>L=\frac{360,000Q_{p}}{\left\{ b+2.388\left[\frac{Q_{p}n}{\left(2\sqrt{1+m^{2}-m}\right)S^{\frac{1}{2}}}\right ]^{\frac{3}{8}}\sqrt{1+m^{2}} \right \}q}</math>
<math>L=\frac{360,000Q_{p}}{\left\{ b+2.388\left[\frac{Q_{p}n}{\left(2\sqrt{1+m^{2}-m}\right)S^{\frac{1}{2}}}\right ]^{\frac{3}{8}}\sqrt{1+m^{2}} \right \}q}</math>


{Plainlist|1=Where:
{{Plainlist|1=Where:
*L = length of swale in m
*L = length of swale in m
*Q<sub>p</sub> = peak flow of the storm to be controlled, in m<sup>3</sup>/s
*Q<sub>p</sub> = peak flow of the storm to be controlled, in m<sup>3</sup>/s
Line 17: Line 17:
*S = the longitudinal slope (dimensionless)
*S = the longitudinal slope (dimensionless)
*n = Manning's coefficeint (dimensionless)
*n = Manning's coefficeint (dimensionless)
*b = bottom width of trapezoidal swale, in m.}
*b = bottom width of trapezoidal swale, in m.}}





Revision as of 00:32, 29 September 2017

These sizing equations are suggested for use in calculating the capacity of swales which have a larger proportion of surface flow. i.e. grass swales, rather than bioswales.


Triangular channel[edit]

Sizing a triangular channel for complete volume retention:

Trapezoidal channel[edit]

Sizing a trapezoidal channel for complete volume retention:

Where:

  • L = length of swale in m
  • Qp = peak flow of the storm to be controlled, in m3/s
  • m = swale side slope (dimensionless)
  • S = the longitudinal slope (dimensionless)
  • n = Manning's coefficeint (dimensionless)
  • b = bottom width of trapezoidal swale, in m.