Methods or techniques of irrigation

Irrigation Methods

1. Chapter – 3
Methods of Irrigation

Pokhara University
Faculty of Science and Technology
School of Engineering

Er. Anand Dev Bhatt
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2. Methods of Irrigation
(Methods of applying water to crops/techniques of water distribution)

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3. Surface Irrigation:

It is the irrigation technique in which water is applied
and distributed over soil surface by gravity.

It is the most common form of irrigation method
throughout the world.

Surface irrigation method is further divided into:
1.Flooding method

2.Furrow method

3.Contour farming



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4. 1. Flooding Method:

It consist of opening a water channel in a plot or field
so that water can flow freely in all directions (i.e.
water is flooded in land) and cover the surface of the
land in a continuous sheet.

It is further sub-divided into:

A.Uncontrolled/Wild Flooding:

In this method water is spread or flooded on the
smooth flat land, without much control or without
prior preparation of land in the form of ditches or
borders.


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5. A.Uncontrolled/Wild Flooding (C0ntinue…)

Wild flooding is earliest and primitive method of
application of water to the land.

The water is allowed to flow the natural slope of the
land.

In this method water is forced to spread over the
land during season of high stream flow.


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6. B.Controlled Flooding:

In controlled flooding methods irrigation water is
applied by spreading it over the land to be irrigated
with proper control on the flow of water as well as
the quantity of water applied.

All the methods of control flooding require prior
preparation of the land (in the form of necessary
ditches and borders).

The land is properly graded(leveled) & agricultural
fields are divided into small units by levees .



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7. B.Controlled Flooding(Continue…):

The various methods of controlled flooding are:

i.Free flooding
ii.Contour laterals
iii.Border strips
iv.Check basins
v.Basin flooding
vi.Zig-zag method

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8. i.Free flooding:
This method consists of dividing the entire land to be
irrigated in to small strips by a number of field
channels known as laterals.
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Field Channels
(Laterals)
Note: This fig. actually resembles to furrow method. Here is cited only for understanding the concept of laterals.

9. These laterals may be either at right angles to the
sides of the field or at right angles to the contour
lines as shown in figure.
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Contour
Lines
Side of
the field

10. When laterals are aligned at right angles to the sides
of the field, irrigation is possible only to one side to
lateral (field channel),

When laterals (or field channel) are aligned at right
angles to the contours, irrigation is possible on both
sides of laterals as shown in above fig.,

The field channels receive water from the main
supply channel and discharge excess water in the
waste channel,

This method is used for both flat as well as for
relatively steep land,

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11. ii.Contour Laterals(Flooding by Contour Laterals):

This is a special case of free flooding in which the
field channels or laterals are aligned approximately
along the contour lines.
In this method, irrigation is possible only on side of
the laterals.
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12. iii.Border Strip Flooding:
In this method land/farm is divided into series of
strips 10 to 20m wide and 100 to 300m long by levees
(i.e. small bunds).
This method is suitable when the area is at level with
gentle slope.
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Levees or Borders

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Fig.: Border Strip Flooding Method

14. iv.Check Flooding:
Similar to free flooding except that crop area is divided into
some plots (or check basin area) and water is controlled by
surrounding the plots by small levees.
Since whole area divided into nos. of plots so it is also called
‘Irrigation by Plots’.
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Plot
Plot

15. v.Basin Flooding:
It is a special type of check flooding method.
This method is used frequently to irrigate the plantations or
used in gardens.
Each plant is enclosed by circular channels which is called
basin. Basins are connected to small field ditches.
Field Ditches are fed from the main supply channel.
One Ring Basin may be formed for two or more trees.

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16. vi.Zig-zag Method:
In this method, the agricultural area is sub-divided
into small plots by low bunds in a zig-zag manner.
The water is supplied to the plots from the field
channel through the openings.
The water flows in a zig-zag way to cover the entire
area. When the desired depth is attained, the
openings are closed.
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17. 2. Furrow Method:

Row crops such as potatoes, maize, cotton, sugarcane,
vegetable etc. can be irrigated by furrow method.

In flooding method, water covers the entire surface; while in
furrow method, only one-fifth to one-half of land surface is
wetted by water.

Thus furrow irrigation avoids flooding the entire field surface
by channeling the flow along the primary direction of the field
using ‘furrows,’ ‘grooves’, ‘lines’.

Furrows are narrow field ditches, excavated between rows of
plants and carry irrigation water through them.

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Furrows
Ridges

19. 3. Contour Farming:
Contour farming is practiced in hilly areas with slopes
and with falling contour.
The land is divided into series of horizontal strips
called terraces.
Small bunds are constructed at the end of each
terrace to hold water up to equal height.

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Terraces Bunds

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21. Sprinkler Irrigation:

Sprinkler method consists of applying the water in
the form of a spray through a network of pipes and
pumps.
It is a kind of an artificial rain and therefore, gives
very good results.


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22. Sprinkler Irrigation(Continue…):
This method is more useful where:
The land cannot be prepared for surface methods,
Slopes are excessive,
Topography is irregular,
Soil is erosive,
Soil is excessively permeable.

It is costly process of irrigation.
Sprinkler system can be further sub divided into
three heads:
i.Permanent system
ii.Semi-permanent system
iii.Portable system


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23. Sprinkler Irrigation(Continue…):

i.In Permanent system, pipes are permanently buried
in such a way that they do not interfere with
farming operations,

ii.In Semi-permanent system, the main lines are
buried in the ground, while the laterals are portable,

iii.In Portable system, the mains as well as laterals are
portable. These portable networks can be move
from one farm to another farm.


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24. Advantages of Sprinkler Irrigation:

Erosion can be controlled,
Uniform application of water can be possible,
Irrigation is better controlled,
Land preparation is not required(i.e. making suitable
gradient, leveled ground is not necessary)
More land will be available for cropping as borders
and ditches are not required(i.e. land consumed by
borders and ditches will be used for cropping),
Labour cost is reduced,
Surface runoff is eliminated,
Small streams of irrigation water can be used
efficiently,


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25. Limitations of Sprinkler Irrigation:

Wind may distort sprinkler pattern and sprinkler
networks too,

Water must be clean and free from sand or other
dust particle (to prevent blockade of sprinkler
notches),

The power requirement is high,


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26. Drip Irrigation:
Drip irrigation is also known as trickle irrigation.
In this method water is applied in the form of drops
directly near the base of the plant.
It is one of the latest developed methods of irrigation
which is more popular in the regions facing scarcity
of water.




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27. Drip Irrigation(Continue…):




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This system involves laying of system of heads, mains, sub-
mains, laterals, and drop nozzles. Water oozes out of these
small drip nozzles uniformly and at very small rate, directly
into the plant roots area.

28. Advantages 0f Drip Irrigation:




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Less requirement of irrigation water,
Water logging avoided,
High crop yield,
No over-irrigation,
Increase in Net Irrigable Area (NCA),
Nutrients of soil prevented (i.e. may not wash out as in
surface irrigation),
Reduces labour cost,
Suitable for any topography,

Disadvantages 0f Drip Irrigation:
High initial cost,
Danger of blockade of nozzles,

29. References:





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Irrigation and Water Power Engineering: Dr. B. C. Punmia
Dr. Pande B.B. Lal
Ashok Kumar Jain
Arun Kumar Jain
(Laxmi Publications (P) Ltd.)
Irrigation Engineering and Hydraulic Structures: S. K. Garg
(Khanna Publishers)

Google.com

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