LIT194-Handbook of TII.pdf - Diamond Head Sprinkler Supply

Coefficient of UniformityThis formula is used to measure the variability of water distribution over a given area. It iscalculated by using a series of catchments and comparing the average (mean) catchment and thedeviation from that average. This formula was developed by J.E. Christiansen.C u = 100( 1.0 - ∑x )mnWhere:C u = Uniformity Coefficientx = the deviation of individual observations or catchments∑x = the sum of the deviations of individual observations from the mean value, mm = mean value of all observations in the distributionn = number of observations in the distribution100 = constant for conversion to percentExample:1Sprinkler HeadCatchment (number)24 53Catchment Quantity Deviation From MeanCatchment Note: catchment # (ml) (mean = 46.75 ml)may be expressed in any convenientunit, 1 i.e. milliliters, ounces, 48 etc. as1.25long as all catchments are measuredin the 2 same units. 51 4.253 44 2.754 41 5.755 45 1.756 44 2.757 50 3.256788 51 4.25Total 26.00Note: catchment may be expressed in any convenient unit ( i.e. milliliters, ounces, etc.), as long as all catchments are measured in the sameunits.In a landscape area, eight catchments are placed between sprinklers and the aboveobservations recorded. What is the Coefficient of Uniformity?C u = 100( 1.0 - 26.0046.75 x 8)C u = 93.0®Handbook of Technical Irrigation Information23