4/3/2012 8:04 AM
James:
You're correct in that if the catch can reads .15 of an inch, that's the water that will hit that spot. You will need enough catch cans to make a grid no more than 15 feet apart, 10 feet is better. If you have a green that's 5,000 ft² you will probably require at least 49 catch cans. Also be certain that the catchments are no closer than 5 feet from any sprinkler. Lay the grid out close to the spacing configuration as possible - square spacing, triangular spacing. You should run each station for at least 10 minutes. Wind should be less than 5 mph. All of the catchment devices need to be identical for the math to work.
To Calculate Distribution Uniformity:
DULQ = Lower Quarter Distribution Uniformity (%)
Average LQ = Average of lower 25% of sample
Average = Average of total sample
DULQ = Avg. LQ / Average
If your DULQ is lower than 55% you'll need to examine precipitation rates and start making changes to nozzles or spacing.
Are you trying to establish a nozzle size change, spacing adjustments, run-time changes, perception rate? There are other calculations, to demonstrate different actions to take to fine tune irrigation but they all begin with a catchment test.
If you would like, you can call or email me, I'd be glad to talk anytime.
Good luck, James