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 (Wf / Ws)

  Wf = 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 / Wf) Ws= Water stored in the root zone

of the plants Wf= Water delivered to field

Range of Application Efficiencies for Various Irrigation Systems

System Type Application Efficiency Range* (%)

Surface IrrigationBasinBorderFurrow Surge

60 – 9560 – 9050 – 90 60 – 90

Sprinkler IrrigationHand move Traveling Gun Center Pivot & Linear Solid Set

65 – 8060 – 7070 – 9570 – 85

Micro irrigationPoint source emitters Line source emitter

75 – 9570 – 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