 The most common definitions are the ratio of yield (Y) to applied water (AW) or the ratio of evapotranspiration (ET) to AW.

 Design of irrigation system  The degree of land preparation  Skill and care of irrigator

 The percentage of average application amount received in the least-watered quarter of the field.  Ud = 100 ( Lq / Xm)  Lq = Average low-quarter depth of water infiltrated (or caught)  Xm= Average depth of water infiltrated

 Uniformity of drip irrigation systems is usually a combination of measuring the variability of emissions from individual emitters and pressure variations within the entire system.  As with the sprinkler systems this method of measuring non-uniformity captures the entire degree of variability.

CONT…….  The greatest utility of measuring uniformity of furrow systems is to guide the management on that particular field.  Irrigation uniformity can be altered by length of furrow, rate of water application, and duration of irrigation.

Irrigation Water Losses

Drawback in conventional irrigation system

Water Conveyance Efficiency (Ec):  The percentage of source water that reaches the field.  Ec = 100 (W f / Ws)  W f = Water delivered to field  Ws = Water diverted from source

Water Storage Efficiency (Es):  The percentage of water delivered to the field is used by the crop.  Es = 100 (Ws / W f )  Ws= Water stored in the root zone of the plants  W f = Water delivered to field

Range of Application Efficiencies for Various Irrigation Systems System TypeApplication Efficiency Range* (%) Surface Irrigation Basin Border Furrow Surge 60 – – – – 90 Sprinkler Irrigation Hand move Traveling Gun Center Pivot & Linear Solid Set 65 – – – – 85 Micro irrigation Point source emitters Line source emitter 75 – – 95

Water Distribution Efficiency (Ed):  The percentage of the average application depth delivered to the least-watered part of the field.  Ed = 100 [ 1- (y/d) ]  y = Average absolute numerical deviation in depth of water stored from average depth stored during the irrigation  d = Average depth of water stored during irrigation