This function determines PELQ as the average of the low quarter catch rates divided by the average catch rate of applied water. As such is is a measure of the potential of the sprinkler irrigation system considering uniformity (low quarter) and any losses due to drift and evaporation (uses catch can rates).
numeric array of catch can depths.
logical; units SI (mm, m, lpm) or US Customary (in., ft, gpm). SI (TRUE) is default.
sprinkler discharge rate (lpm or gpm).
sprinkler spacing (m or ft).
lateral spacing (m or ft).
duration of irrigation event, hr.
catch can depths converted to catch rates.
PELQ (potential application efficiency of low quarter, %
Mirriam and Keller, 1978. Farm System Irrigation Evaluation: A Guide for Management. PP 41-43. Utah State University, Logan, Utah. https://pdf.usaid.gov/pdf_docs/PNAAG745.pdf
#see pp 41-43 of reference document SI<-FALSE # use U.S. customary units x<-c(.23,.31,.24,.24,.28,.31,.27,.22,.26,.31, .31,.25,.20,.22,.32)# catch can depths caught during test converted to in/hr rate<-4.6 # 4.6 gpm sprinkler discharge rate (measured) sl<-50; ss<-30 # 30 x 50 ft sprinkler x lateral spacing dur<-1 # 1 hr test duration (dur. in min) PELQ(x,SI=FALSE,rate,ss,sl,dur) #>  73.64892