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 20:32, 28 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:
![{\displaystyle 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}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/2b2cd1fbb226b90d215b2f9ea3e368ccacc64b90)
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.