The document describes various methods of irrigation including check flooding, basin flooding, furrow irrigation, subsurface irrigation, sprinkler irrigation, and drip/trickle irrigation. Check flooding involves enclosing level plots with small levees and flooding the enclosed area with irrigation water. Basin flooding is a type of check flooding used for orchard trees, with one or more trees placed in flooded basins. Furrow irrigation involves creating small parallel channels for water to flow down the field. Subsurface irrigation applies water from beneath the soil surface using trenches or perforated pipes. Sprinkler irrigation sprays water into the air to break into small drops and fall to the ground, similar to natural rainfall. Drip/trickle irrigation slowly applies water

1. 1
(c) Check Flooding:
In this method, relatively level plots are enclosed by small levees or
embankments. Irrigation water enters the closed area and
subsequently floods it. Check flooding method is very suitable for
soils having high permeability. The reason is that the water quickly
spreads over the entire area before it goes deep, below the root
zone depths, into the ground and joins the water table. Thus, the
water loss due to infiltration is prevented or reduced.
It is best adopted for heavy soils also. In heavy soils water
absorption rates are low. The land can be kept flooded for longer
time till sufficient water infiltrates into the ground to fulfill soil-
moisture deficiency. This method can be subdivided into two
groups depending upon the mode of levee construction. The
subdivisions are the following:
(i) Rectangular Check
(ii) Contour Check
Lecture-7

2. 2
Ditch Openings
Levees along the contours
Connecting
Figure: Plan view of Check flooding
Otherwise the embankments or levees may put hindrance to farm
machinery. This method is very useful in leaching the soil and
reducing the salinity. It is generally used for grain and fodder crops.
In check method 0.2 to 0.8 hectares area is better. The
embankment should be about 25 to 30 cm high and the width
at the base should not be more than 2.5 m.
Lecture-7(contd.)

3. 3
Lecture-7(contd.)
Photograph of Check irrigation

4. 4
Lecture-7(contd.)
(d) Basin Flooding
This method is special type of checking flooding and is adopted
specially for orchard trees. One or more trees are generally placed in
the basin, and the surface is flooded as in check method, by ditch
water as shown the following figure.
Tree Tree
Tree Tree Tree
Tree
Basins
Subsidiary
ditches
Entry water
through a bank
hole or by a
hose
Main ditch

5. 5Photograph of basin flooding method

6. 6
Lecture-7(contd.)
(e) Furrow irrigation
Probably one of the oldest methods of irrigating fields is surface
irrigation or furrow irrigation, where farmers flow water down small
trenches running through their crops. Or it is a narrow field ditch
excavated between two rows of plants and carry irrigation water
through them.
In furrow irrigation only one-fifth and one-half of the land surface is
wetted. Results is less evaporation and permits cultivation sooner after
irrigation. Figure-3
Furrow irrigation is conducted by creating small parallel channels
along the field length in the direction of predominant slope. Water is
applied to the top end of each furrow and flows down the field under
the influence of gravity.
At furrow irrigation, soil conditions, the land relief and slope, row-
spacing width or interval between the furrows are taken into account.

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Figure 3 : Furrow irrigation
Figure : Furrow
Depth and width of irrigation
furrows:
According to depth, volume of
filling and consequently hydraulic
features furrows are of three
types:
(i) shallow furrows : 10…15 cm
deep, 30…35 cm wide on the top
(ii) medium-depth furrows :
15…20 cm deep and 40…45 cm
wide on the top
(iii) deep furrows are 20 to 30
cm deep and 50to 60 cm wide on
the top.
Lecture-7(contd.)

8. 8
2. Sub Surface method
Sub surface irrigation, also designated as sub irrigation. This
method involves irrigation to crops by applying water from
beneath the soil surface either by constructing trenches or
installing underground perforated pipe lines or tile lines. Water is
discharged into trenches and allowed to stand during the whole
period of irrigation for lateral and upward movement of water by
capillarity to the soil between trenches.
Lecture-7(contd.)
Photograph of sub surface irrigation method
Water supply
through pipe
beneath the soil

9. 9
Lecture-7(contd.)
3. Sprinkler irrigation: is a method of applying irrigation
water which is similar to natural rainfall. Water is distributed through a
system of pipes usually by pumping. It is then sprayed into the air
through sprinklers so that it breaks up into small water drops which fall
to the ground. Figure : Sprinkler irrigation system.
But this method is very costly. It can be applied for all kinds of soil and
for widely different topographies and slopes. It can advantageously be
used for many crops, because it fulfills the normal requirement of
uniform distribution of water. This method possesses great
potentialities for irrigating areas where other types of surface or
sub surface irrigation are very difficult.

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Figure: Sprinkler irrigation system
Lecture-7(contd.)

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Lecture-7(contd.)
The 6 conditions favoring the adoption of this method are:
i. irregular land topography and unsuitable for
surface irrigation
ii. when the land gradient is steeper and soil is
easily erodible
iii. when the soil is highly impermeable.
Field Sprinkler irrigation method

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iv. When the water table is high
v. When the seasonable water requirement is low such as near the
coasts
vi When the crops 5equire humidity control, having shallow roots and
crops requiring high and frequent irrigation
Types of sprinkler systems: It is of three kinds, they are
1.Permanent system
2.Semi-permanent system and
3. Portable system
Lecture-7(contd.)

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Lecture-7(contd.)
4. Drip/ Trickle Irrigation method
Drip irrigation is the latest field irrigation technique, and is meant
for adoption at places where there exists acute scarcity of
irrigation water and other salt problems. In this method, water is
slowly and directly applied to the root zone of the plants, thereby
maintaining the losses by evaporation and percolation.
Drip irrigation is a form of irrigation that saves water and
fertilizer by allowing water to drip slowly to the roots of
many different plants, either onto the soil surface or directly
onto the root zone, through a network of valves, pipes,
tubing, and emitters.
It is done through narrow tubes that deliver water directly to
the base of the plant. This method is also called trickle
irrigation.

14. 14
Lecture-7(contd.)
Figure: Drip System
Photograph: A vineyard
with a drip irrigation
system running along the
bottom of the vines

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Lecture-7(contd.)
2. No water logging and rise of water
table
3. No salinity problems caused by this
irrigation type is almost nil.
4. Uniform distribution of water.
5. Good water management.
6. Economical use of labor.
Advantages
1. No loss of water because
all water drops at root zone.
Image: Drip watering system
Water drops falling

16. 16
Lecture-7(contd.)
Canal irrigation system
An open canal, channel, or ditch, is an open waterway whose purpose is to
carry water from one place to another. Channels and canals refer to main
waterways supplying water to one or more farms. Field ditches have smaller
dimensions and convey water from the farm entrance to the irrigated fields.
These canals have to be excavated either in alluvial soil or non-alluvial soils;
depending upon which they are called alluvial or non-alluvial canals.
Alluvial soils: The soil which is formed by transportation and deposition of silt
through the agency of water, over a course of time, is called alluvial soil.
Non-alluvial soils: Mountainous regions may go on disintegrating over a
period of time, resulting in the formation of a rocky plain area, is called
non-alluvial area. It is an uneven topography, and hard foundations are
generally available.

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Canal Alignment
Lecture-7(contd.)
Irrigation canals can be aligned in any of the following three ways:
a. watershed canal or ridge canal
b. contour canal; and
c. side slope canal
River
Watershed/Ridge line
P Q Rl.3.5m A Rl. 3.0 m
Ridge
line
B (Rl. 2.0 m
L1
L2
L3
L1Canal
a. Watershed canal
The dividing ridge line
between the catchment
areas ( the area from which
rain water flows into a
drain or a stream, is known
as its catchment area) of
two streams (drains) is
called the water –shed, or
the ridge.

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Thus, between two major streams, there is main water –shed
line which divides the drainage area of two streams as shown in
the previous figure. Similarly, between a main stream and any of
its tributary, there are subsidiary watersheds (ridge line) dividing
drainage between the two streams on either side.
Lecture-7(contd.)

19. 19
Lecture-7(contd.)
Example of Watershed canal

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Side Slopes canal
3.0 m 2.0 m 1.5 m
Ground contours
Figure: Alignment of side slope
canal
b. Side Slope Canal
This canal aligned roughly perpendicular
to contour of the contour. Since it is
perpendicular to the contour, construction
of cross Drainages Works (CDWs) does
not arise. Since constructed along the
falling contour, slope of this canal is
steep, which is not essential for unlined
canal. It irrigates only on one side just
like contour canal.
Lecture-7(contd.)
Sideslopeirrigationcanal

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Lecture-7(contd.)
c. Contour canal: The canal constructed along the ridge line
are called contour canal. It is uneconomical in hill areas since the
conditions in hills are vastly different compared to those of plain lands.

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In hills , the river flows in the valley well below the water – shed. In fact
the ridge line is 100 meters above the river which is generally
impossible to take the canal on top of such a higher ridge line. In such
conditions, contour canals (as shown the figure-2) are usually
constructed. A contour canal irrigates only one side because the area on
the side is higher. As the drainage flow is always at right angles to the
ground contours, such channel would definitely have no cross natural
drains and streams, necessitating of cross-drainage structures.
Distribution system of canal irrigation
Direct irrigation scheme using a weir or a barrage, as well as
storage irrigation scheme using a dam or a reservoir,
requires a network of irrigation canals of different sizes and
capacities.
Lecture-7(contd.)

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Lecture-7(contd.)
The entire network of irrigation channels (Figure 8-6 ) is
called the distribution system of canal irrigation.

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The canal system consists of
1. Main canal
2. Branch canals
3. Distributaries also called major distributaries
4. Minors
5. Water courses
1.Main canal: The canal constructed or aligned along the
ridge and some what central to the command area
receiving water from reservoir or river is called main canal.
Main canal is not required to do any irrigation.. The canal
must, therefore, be aligned very carefully, and has to be
generally excavated in deep cuttings below NSL(Natural
surface level). Sometimes, it has to cross various drainage
lines.
Lecture-7(contd.)

25. 25
Lecture-7(contd.)
2.Branch canal: Branch canals are taken off from the main canal on
either side to take irrigation water to the whole tract required to be
irrigated
3. Distributaries: Small channels which take off from the branch
canals and distribute their supply through outlets into minors or
water courses, are called distributaries. They are aligned either as
ridge canals or as cotor canals.
Photograph:Distributaries

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4. Minor: Sometimes distributaries outlet and the farmer’s field is
very long, say more than 3 km or so on. In such a case, small
channels called minors are taken off from distributaries, so as to
supply water to the cultivators.
5. Water courses : The small channels, which are excavated
and maintained by the cultivators, at their own costs, to take
water from the government-owned outlet points, provided in the
distributaries or the minor.
Lecture-7(contd.)
Photograph:
waterdistributionby
artificialcanalsystem