Rainfall Intensity Calculation based on Time Concentration

[Maulin Patel]

Is there a formula for calculating the Rainfall Intensity from critical storm period.
Something like this formula: I = A*(Tc)^B + C;
where, I is the Intensity of rainfall,
Tc is time of concentration
and A,B & C are any curve fitting parameters, which I DONT KNOW.!!!
Thank You.

 

[beej67]

Although the isohyetal maps are old, this is a good reference for the math: (HYDRO-35)

http://www.nws.noaa.gov/oh/hdsc/PF_documents/TechnicalMemo_HYDRO35.pdf

Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East -

http://www.campbellcivil.com

 

[psmart]

Depending on where you're located, your stormwater regulations would be the best source for that information.

Peter Smart
HydroCAD Software

http://www.hydrocad.net

 

[chicopee]

The standard handbook of environmental engineering by Robert A. Corbitt has two formulas for rainfall intensity and the necessary precipitation charts similar to those in the document presented by beej67. The formulas do not use time of concentration but will use duration. The forms that these two formulas take on the following forms:
I=A/(Td+C)^b or A/(Td^B+C); A is a constant dependent on return period; B&C are constant independent of return period; Td is duration; I is intensity. You'll need to review tables that shows the values of these constants as in table 7.1 in my env. eng. hdbk..