rational.sdsu.edu:   Calculation of peak discharge by the rational method    

Box culvert at highway crossing.
Formula:

Qp = C I A
In SI Units (metric):  L s-1, mm hr-1, and hectares (ha).
In U.S. Customary Units:  cfs, in hr-1, and acres (ac).
INPUT DATA:

Select:   

Runoff coefficient C :      

Rainfall intensity I :      

Drainage area A :      

OUTPUT:

Peak discharge Qp :     

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