Percent Impervious/Runoff Coefficient for prior to sucess of revegetation?
Percent Impervious/Runoff Coefficient for prior to sucess of revegetation?
(OP)
What percent impervious/runoff coefficient would you use for the Rational Method for an area that has just been re-graded and probably has hydromulching or something similar but no actual vegetation yet? Also has steep slopes. I'm using 5% for undisturbed areas and was thinking 30% was appropriate for interim conditions but a colleague thinks it should be more like 80% (he has yet to produce any backup for this).
Thanks for your opinions.
Thanks for your opinions.





RE: Percent Impervious/Runoff Coefficient for prior to sucess of revegetation?
http://www.elibrary.dep.state.pa.us/dsweb/Get/Docu...
Page 111 gives runoff coefficients for bare soil between 0.2 & 0.6 depending on the Hydrologic soil group and slope.
Hope this helps
RE: Percent Impervious/Runoff Coefficient for prior to sucess of revegetation?
Thanks!
RE: Percent Impervious/Runoff Coefficient for prior to sucess of revegetation?
Another example from Maricopa County for un-disturbed land
The variation is for 2-year vs 100-year storm
rangeland (slopes less than 5%) .40 - .50
hillslopes (slopes greater than 5%) .55 - .69
mountain terrain slopes greater than 10%) .80 - .95
Table 6.4
http://www.fcd.maricopa.gov/Pub/Manuals/downloads/...