This document discusses uniformity coefficients for drip and sprinkler irrigation systems. It defines uniformity coefficient as a ratio that expresses the variation in particle sizes for a material. For sprinkler systems, Christiansen's uniformity coefficient is commonly used, where a value of 85% or more is considered satisfactory. The coefficient evaluates the uniformity of water application. For drip systems, Christiansen's formula only broadly indicates uniformity, as emitters differ from sprinkler nozzles. Emitter discharge variability depends on factors like operating pressure and temperature fluctuations. The document also introduces design emission uniformity, a metric proposed by Karmeli and Keller to evaluate drip system performance.

1. SWE 211
FUNDAMENTALS OF SOIL AND
WATER CONSERVATION
ENGINEERING
PRESENTATION ON
UNIFORMITY COEFFICIENT OF DRIP AND SPRINKLER IRRIGATION
SYSTEMS
PRESENTED BY
SUBBULINGAM.S
2016033076

2. UNIFORMITY COEFFICIENT
• It is a ration expressing the variation in grain size of a granular
material.
• Its is the quotient obtained by dividing the sieve aperture that passes
60% of the material by the sieve aperture that passes 10% of the
material.
𝑪 𝒖=
𝑫 𝟔𝟎
𝑫 𝟏𝟎

3. • The typical sieve analysis curves of water bearing sands and gravels
states that the well graded sand with good aquifer and no artificial
gravel packing have the uniformity coefficient of 0.75mm divided by
0.25mm or 3.0
• This ratio was proposed by Hazen as a quantitative expression of the
degree of assortment of water-bearing sand as an indicator of
porosity.

4. C 𝒖 OF SPRINKLER IRRIGATION SYSTEMS
• Christiansen’s uniformity coefficient (UC) is the most commonly used
statistical method for evaluating sprinkler system uniformity (Morgan,
1964; Warrick, 1983). Christiansen’s uniformity is defined as:
C 𝒖 = 100 (1.0 - x/mn)
m = average value of all observations (average application rate) ,mm.
n = total number of observation points
x = numerical deviation of individual observations from the average
application rate ,mm.

5. • An uniformity coefficient of 100 per cent (obtained with overlapping
sprinklers) is indicative of absolutely uniform application ,whereas the
water application is less uniform with lower percentage.
• An uniformity coefficient of 85% or more is considered to be
satisfactory.

6. Use of estimating C 𝒖
• The data on uniformity coefficient are useful as a basis for selecting
the combination of spacing ,discharge ,nozzle size and operating
pressure to obtain high values of irrigation efficiency at specify
operation conditions.

7. EMISSION UNIFORMITY IN DRIP IRRIGATION
SYSTEM
• The coefficient of uniformity proposed by Christiansen(1942) is widely
accepted for estimating the uniformity in water application in
sprinkler irrigation systems.
• The christiansen’s formula , when applied to drip irrigation system will
give only a broad indication of a uniformity of water application ,as
the emission characteristics of droppers used in drip systems are
significantly different from those of sprinkler nozzles.

8. • The water application uniformity of emitters (except pressure
compensating type emitters)is nfluenced by the operating
pressure,emitter spacing ,land slope ,size of the pipe line,emitter
discharge rate,emitter discharge variability.
• The emitter discharge variability is due to the variations in operating
pressure and temperature , manufacturing variability (coefficient of
variations, C 𝑢 ),clogging and aging of the emitters.

9. DESIGN EMISSION UNIFORMITY(UNIFORMITY
COEFFICIENT)
• Karmeli and Keller(1975) were the first to define a empirical designing
emission uniformity EU for the evaluation the performance of drip
irrigation systems (Hillel.D 1982).
EU = 100 [1.0-
1.27C 𝒖
𝒏
]
𝒒𝒎
𝒒𝒂
In which ,
EU = design emission uniformity,
qm = the minimum emitter discharge rate for a minimum pressure in
the section .
qa = the average or design emitter discharge for the section.

10. THANK YOU 