Here are the potential efficiencies in irrigation systems: - Conveyance efficiency (Ec) - The ratio of water delivered to the farm or field to water diverted from the source. Ranges from 60-90%. - Application efficiency (Ea) - The ratio of water stored in the root zone to water delivered to the field. Ranges from 50-80%. - Distribution uniformity (DU) - A measure of uniformity of water application within the field. Higher is better, above 85% is good. - Storage efficiency (Es) - The ratio of water stored in the root zone to water needed to refill the root zone. Ranges from 80-95%. - Water

1. DRIP
IRRIGATION
SYSTEM
Dr. G.K. Nigam
Ph.D. (Soil & Water Engg.)

2. • Irrigation Water Management is the process of
determining and controlling the volume, frequency, and
application rate of irrigation water in a planned, efficient
manner.
Irrigation Water Management
Why is Irrigation Water Management Important?
– Manage soil moisture to promote desired crop
response.
– Optimize the use of available water supplies.
– Minimize irrigation induced erosion.
– Decrease non-point source pollution of surface
and groundwater resources.
– Manage salts in the crop root zone.
– Manage air, soil or plant micro-climate.

3. Crop Water Requirements
Some terms used in crop water requirement
1. Consumptive Use: Quantity of
water lost in evaporation, transpiration
and that used by the in metabolic
activities.
1. Evapotranspiration: Total water
loss due to transpiration from a crop
and evaporation from the soil for a
particular area during a specific time.
1. Water Requirement: It is the water
needed for raising crops in given
period, it includes consumptive use
and other loses .

4. Crop period : The time period from the sowing of the crop to the instant of
its harvesting is called a crop period.
Base Period : The time period from the first watering of the crop during its
sowing to the last watering of the crop before its harvesting is called a base
period.
Mostly, the crop period is greater than the base period. Practically, both terms are
considered same and are expressed in days.
Last
watering
1st
watering
Sowing Harvesting
Base period
Crop period

5. Delta and Duty of a Crop

6. PALEO Irrigation
Sometimes, in the initial stages before the crop is sown, the land is very dry.
In such cndition, the soil is moistened with water as it helps in sowing the
crops. This is known as paleo irrigation.
KOR
Watering
The first watering which is given to a crop, when crop is few cm high is called
KOR Watering.
Last
waterin
g
1st
watering
Sowing Harvestin
g
Base period
Crop period
PALEO
Irrigation

7. • The amount of water needed to the compensate the
evapotranspiration (ET) loss from the crop field termed as Crop
water requirement.
• Crop water requirement represents the ET under ideal crop growth
condition.
• It varies with time and space, as the ET demand varies with climate
and crop condition
Every crop require a certain quantity of
water after a certain fixed interval,
throughout its growth period. If the natural
rainfall is sufficient and timely so as
satisfy both these requirement, no
irrigation water is required to raising that
crops. The water requirement of the crop is
the total quantity of water required for a
crop from the time it is sown to the time it
is harvested.

8. Factors affecting of Crop water requirement
⮚ Crop Factors
⮚ Types of crops
⮚ Cultivar/ species
⮚ Growing stage
⮚ Leaf area
⮚ Root length, root density
⮚ Weather Factors
⮚ Temperature
⮚ Radiation
⮚ Humidity
⮚ Wind seed

9. Water requirement of different crops

10. Calculation for crop water requirements
ETc = Kc x ETo
ETc : Crop evaporation or crop water need (mm/day)
Kc : Crop factor
ETo : Reference evapotranspiration (mm/day)
Kc is mainly depends on :
⮚ The type of crop
⮚ The growth stage of the crop
⮚ The climate
ETo is measure/predict by :
⮚ Using evaporation pan
⮚ Using Penman-Monteith Equation
⮚ The Blaney-Criddle Equation
ETo = Kp x ETpan
Where,
Kp : Pan coefficient
ETpan : Evaporation of the pan

11. ETcr = Crop
evapotranspiration
(mm/day)
Kc = Crop coefficient
ETo = Reference crop
evapotranspiration
(mm/day)
Crop coefficient

12. Values of the crop factor (Kc) for various crops

13. Gross Commanded Area (GCA)
The total area lying between drainage boundaries
which can be commanded or irrigated by a canal
system or water course is known as gross commanded
area.
Culturable Commanded Area (CCA)
Gross commanded area contains some unfertile barren
land, local ponds, villages, graveyards etc which are
actually unculturable areas. The gross commanded
area minus these unculturable area on which crops can
be grown
satisfactorily is known as Culturable Commanded
Area.
CCA = GCA – Unculturable Area

14. Culturable Cultivated Area
The area on which crop is grown at a particular time or
crop season.
Culturable Uncultivated Area
The area on which no crop is grown at a particular time
or crop season
Intensity of Irrigation (I.I)
It is the percentage of CCA that is cultivated in a
particular season.
Crop ratio
The ratio of area irrigated in Rabi season to that irrigated in
Kharif season .
The crop ratio is so selected that the discharge in the canal
during both the seasons may be uniform.

15. Example:
If the rice requires about 20 cm depth of water at an average interval
of about 10 days. and the crop period for rice is 150 days, find out the
delta for rice.
Solution.
Water is required at an interval of 10 days for a period of 150
days.
Hence, No. of required waterings = 150/10 = 15
Total depth of water required = No. of waterings x Depth of
Watering
15*20=300 cm

16. No. of required waterings = 140/28 = 5
The depth of water required each time = 7.5 cm.
Total depth of water reqd. in 140 days = 5 x 7.5
cm = 37.5 cm
Hence, Delta for wheat = 37.5 cm. Ans.
Example:
If wheat requires about 7.5 cm of water after every 28 days, and the
base period for wheat is 140 days, find out the value of delta for
wheat.

17. Example:
Find the delta for a crop when its duty is 864 hectares/cumec on the
field. The base period of this crop is 120 days.
Solution.
B = 120 days
D = 864 hectares/cumec
Δ(cm) = 864 B / D
= 864 x 120 / 864
= 120 cm

18. Water content of the soil
• Gravity water: Water that drains through the
soil into the water table – not usually considered
available to plants
• Capillary water: water held in interstices in the
soil – available to plants
• Hydroscopic water: water chemically bonded to
the soil - not usually considered available to
plants

19. FACTORS AFFECTING DUTY
The duty of water of canal system depends upon a variety of
the factors.
1. Methods and systems of irrigation
2. Mode of applying water to the crops
3. Methods of cultivation
4. Time and frequency of tilling
5. Types of the crop
6. Base period of the crop
7. Climatic conditions of the area
8. Quality of water
9. Method of assessment
10. Canal conditions
11. Character of soil and sub-soil of the canal
12. Character of soil and sub-soil of the irrigation field

20. Water content of the soil

21. Net irrigation water requirement: It is defined as the water required
by irrigation to satisfy crop evapotranspiration and auxiliary water needs that
are not provided by water stored in the soil profile or precipitation.
• It is the total quantity of water necessary for crop successful growth.
• It is expressed in millimeters per year or in m3/ha per year.
• It depends on the cropping pattern and the climate.
Irrigation Water Requirement
It is total quantity of water required during the cropping period for successful
crop cultivation.
Fn= ETc + Aw – Pe - GW - ∆
SW
where:
Fn = net irrigation requirement for period considered
ETc = crop evapotranspiration for period considered
Aw= auxiliary water—leaching, temperature modification, crop quality
Pe = effective precipitation during period considered
GW = ground water contribution
∆SW = change in soil-water content for period considered

23. Factors affecting of Irrigation Water Requirement
⮚ Weather, Crop and soil factors influence in
determining irrigation water requirement.
⮚ Soil Factor
⮚Soil type (Storage and release properties of water)
⮚Organic matter (control its storage and release
properties)
⮚Soil texture (seepage and percolation rate : sandy soil >
silt > clay soil)
⮚Other Factors
⮚Effective rainfall
⮚Water requirement for leaching of salt
⮚Water requirement for land preparation and land
soaking

24. The root zone
Root depth (full
grown)
Shallow
Beans 0.6-0.7 m
Grass 0.4-0.6 m
Rice 0.5-0.7 m
Medium
Barley 1.0-1.5m
Grains (small) 0.9-1.5 m
Sweet potatoes 1.0-1.5 m
Tomatoes 0.7-1.5 m
Deep
Alfalfa 1.0-2.0 m
Orchards 1.0-2.0 m
Maize 1.0-2.0 m
Available water

25. Irrigation Efficiency
• Efficiency is the ratio of the water output to the water
input, and is usually expressed as percentage. Input
minus output is nothing but losses, and hence, if
losses are more, output is less and, therefore,
efficiency is less. Hence, efficiency is inversely
proportional to the losses. Water is lost in irrigation
during various processes and, therefore, there are
different kinds of irrigation efficiencies.
• The term irrigation efficiency expresses the
performance of a complete irrigation system or
components of the system.

26. • The term irrigation efficiency expresses the
performance of a complete irrigation system or
components of the system.
• Irrigation efficiency is defined as the ratio between
the amount of water used to meet the consumptive
use requirement of crop plus that necessary to
maintain a favourable salt balance in the crop root
zone to the total volume of water diverted, stored or
pumped for irrigation.
• If water applied by the irrigation system and not
being made available to be taken up by plant roots is
wasted and reduces irrigation efficiency

27. It is the ratio between the water that reaches a farm or field and
that diverted from the irrigation water source.
Ec = 100 ( Vf / Vd )
Ec= the conveyance efficiency (%),
Vf = the volume of water that reaches the farm or field (m3),
Vd= the volume of water diverted (m3) from the source.
Water Conveyance Efficiency:
• Seepage
• Consumptive Use by vegetation & evaporation
• Leakage around structures
Conveyance Losses

28. Application Efficiency:
• Application efficiency relates to the actual storage of water in
the root zone to meet the crop water needs in relation to the
water applied to the field.
• It is the ratio of volume of water stored in the root zone to
volume of water delivered to the field.
Ea = 100 ( Vs / Vf )
Where,
Ea= the application efficiency (%),
Vs= the volume of water stored in root zone (m3),
Vf = the water delivered to the field or farm (m3).

29. Water Storage Efficiency
It is the ratio of the water stored in the root zone
during irrigation to the water needed in the root zone
prior to irrigation ( i.e. field capacity – existing
moisture content ).
Water stored in the root zone during irrigation
Water needed in the root zone prior to irrigation
=

30. Water Use Efficiency
• The term water use efficiency denotes the production of crops per unit
water applied.
• It is expressed as the weight of crop produce per unit depth of water
over a unit area. i.e., kg/cm/ha.
Crop Water Use Efficiency
It is the ratio of crop yield per amount of water depleted by the crop in
the process of evapotranspiration (ET).
Crop water use efficiency = Y/ET
Field Water Use Efficiency
It is the ratio of crop yield (Y) to the total amount of water used in the
field (WR).
Field water use efficiency = Y/WR

31. Water Distribution Efficiency
It is a measure of water distribution within the field. A low distribution
efficiency means non-uniformity in the distribution of irrigation water.

32. Irrigation Efficiency
Ec X Ea
It is the product of Application efficiency and conveyance
efficiency
If the connivance efficiency is zero
Irrigation efficiency = Application efficiency
At canal conveyance loses are due to seepage, deep
percolation, runoff, evaporation etc.

33. Coefficient of Uniformity
The Uniformity Coefficient of the drip irrigation system was found to be
varies 0.93 to 0.95. The high value of Uniformity Coefficient indicated the
excellent performance of drip irrigation system in supplying water
uniformly throughout the laterals

34. Field Irrigation Requirement (FIR):
It is the amount of irrigation water required to meet the net irrigation
requirements plus the water lost at the field (i.e in percolation in the
field water courses, field channels and field application of water). If ηa
is water application efficiency:
Gross Irrigation Requirement (GIR):
It is the sum of water required to satisfy the field irrigation
requirement and the water lost as conveyance losses in distrbutaries up
to the field. If ηc is the water conveyance efficiency, then
FIR=NIR/ ηa
GIR = FIR/ ηc

35. What are the potential efficiencies?