Rational Method - Runoff Coeficient - Newbie
Rational Method - Runoff Coeficient - Newbie
(OP)
Hey guys:
I would like to know where can I find a step-by-step procedure to calculate peak runoff and volume of a 8.2 Acre site.
I am using the Rational Formula Q=CiA, I know the Area "A", and the type of coverage that is gravel so I would like to know what runoff coeficient "C" should I use for this type of coverage.
Also, how do I calculate the rainfall intensity "i" for 10yr, 25yr and 100yr storms and a 24hr duration? I am located in New England and have a IDF curve.
Oh by the way I am trying to do manual calculations so I am kinda lost...got used to using computers too much.
Thanks for any help and advice.
I would like to know where can I find a step-by-step procedure to calculate peak runoff and volume of a 8.2 Acre site.
I am using the Rational Formula Q=CiA, I know the Area "A", and the type of coverage that is gravel so I would like to know what runoff coeficient "C" should I use for this type of coverage.
Also, how do I calculate the rainfall intensity "i" for 10yr, 25yr and 100yr storms and a 24hr duration? I am located in New England and have a IDF curve.
Oh by the way I am trying to do manual calculations so I am kinda lost...got used to using computers too much.
Thanks for any help and advice.
RE: Rational Method - Runoff Coeficient - Newbie
RE: Rational Method - Runoff Coeficient - Newbie
RE: Rational Method - Runoff Coeficient - Newbie
RE: Rational Method - Runoff Coeficient - Newbie
Find the Tc, most reviewers will accept the SCS method, free software and manual from the NRCS website. Then read across the IDF at that time and presto, you've got I.
For C:
Any civil engineering text will have them, but cvg is right. Get the review agency's chart of them, no sense doing everything w/ C=0.28 only to find they want 0.29. For conservative analysis (and/or if the agency doesn't spec C):
grass C=0.3
woods C=.2
cult. farm C=.4
impervious C=.95
I used to live in both eastern MA and western MA, so if you are near either, I know you will get a lot of "I" indeed ;)
RE: Rational Method - Runoff Coeficient - Newbie
Your help is very much appreciated.