WMS:OC Rational Equation: Difference between revisions

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Flows for the Orange County rational method are calculated from the following equation:  
Flows for the Orange County rational method are calculated from the following equation:  


Q = 0.90(I - F<sub>m</sub>)A
<math> Q = 0.90(I - F_m)A </math>


where:
where:


* Q &ndash; peak flow (ft<sup>3</sup>/s or m<sup>3</sup>/s)
* <math>Q</math> &ndash; peak flow (ft<sup>3</sup>/s or m<sup>3</sup>/s)
* I &ndash; rainfall intensity (in/hr, mm/hr)
* I &ndash; rainfall intensity (in/hr, mm/hr)
* F<sub>m</sub> &ndash; maximum [[WMS:OC Losses|loss rate]], where F<sub>m</sub> = a<sub>p</sub> * F<sub>p</sub>
* F<sub>m</sub> &ndash; maximum [[WMS:OC Losses|loss rate]], where F<sub>m</sub> = a<sub>p</sub> * F<sub>p</sub>

Revision as of 21:07, 13 February 2013

Flows for the Orange County rational method are calculated from the following equation:

where:

  • – peak flow (ft3/s or m3/s)
  • I – rainfall intensity (in/hr, mm/hr)
  • Fm – maximum loss rate, where Fm = ap * Fp
  • A – catchment area (acres)

This equation is very similar to the traditional Rational Method equation. The term I - Fm is often referred to as the effective precipitation.


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