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Lecture Notes on CVL 412: Irrigation Engineering

UNIT-A: IRRIGATION
(Benefits and ill-effects of irrigation. Methods of irrigation. Status of development of irrigation in
India. Functions of irrigation water in plant growth. Delta, Duty, and Base period of crops. Assessment of
requirement of irrigation water for various crops. Crop rotation. Depth and frequency of irrigation. Irrigation
efficiencies. Drainage of irrigated land. Command Area Development & Participatory Irrigation Management
Programs.)

Irrigation is defined as the process of artificial application of water to soil for the purpose of
supplying the moisture essential for full-fledged nourishment of the crops throughout the crop
period in addition to the water already available to the crops from precipitation, soil moisture
in the crop root zone due to flooding and capillary rise from ground water.

It is an age-old art practiced by farmers, science for agricultural scientists, commerce for
entrepreneurs, engineering for irrigation engineers/civil engineers, and management for
administrators.

Irrigation Engineering is planning, survey, investigation, design, construction, operation

and maintenance of an efficient, low cost, socio-economically, ecologically and
environmentally viable irrigation system, including all the structures connected with
irrigation at every phase.

Dry land farming is done by rain water retention only.

Rain-fed farming is done by rain water only as and when it occurs.

Irrigated farming is done by supplementation of irrigation water, as and when required by

the crops, of specific quantity and quality artificially to soil depending upon soil water
already available to crops because of precipitation, flooding and capillary action of ground
water.

NECESSITY OF IRRIGATION: Adequate quantities of good quality water, spatially as

well as temporally, should be readily available in the soil within the root zone for
nourishment of plant life. Such water if not present in the soil naturally it has to be
supplemented by irrigation. Nearly one-third of the earth’s surface receives less than 250mm
of yearly rainfall, another one-third receives only 250mm to 500mm of rainfall annually and
even in the remaining areas rainfall is received within a few monsoon months during the year
like monsoon rainfall in India from mid- June to mid- October. India has total land area 328
million hectares out of which the cultivated area is 208.5 million hectares and irrigated area
of 72.1 million hectares (34.65% of cultivated area).

Following factors necessitate irrigation:

(i) Inadequate precipitation, (ii) Uneven distribution of precipitation, both spatial and
temporal, (iii) Growing a number of crops during a year, (iv) Growing superior crops of high
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yielding varieties, and (v) Increase food, fodder and fibre production commensurate with
requirement of the State/National population of human and cattle.

BENEFITS OF IRRIGATION: (i) Increase in food production, (ii) Protection from

droughts and famines, (iii) Cultivation of superior (cash) crops like sugarcane, tobacco,
cotton, etc. (iv) Addition of wealth of country due to revenue generation and export of food
grains and other farm produces, (v) Increase in overall prosperity of people, (vi) Provide
work for labour, more pisciculture, recreational facilities (boating, fishing, and swimming),
(vii) Generation of hydro-electric power from canal falls, (viii) Domestic and industrial water
supply, (ix) Inland navigation through canal system, (x) Improvement of communication, (xi)
Plantation along canal banks, (xii) Increase in ground water recharge, (xiii) Aid in
civilisation, (xiv) Social upliftment of people, (xv) Elimination of mixed cropping, and (xvi)
Reduces damages due to floods.

ILL-EFFECTS OF IRRIGATION: Irrigation itself has no defects or ill-effects. The ill-

effects associated with irrigation are caused due to over irrigation, bad farm management,
improper tillage, and bad planning. The possible ill-effects are:

(i) Pollution of stream flows and ground water through seepage of nitrates and other toxic
materials applied as fertilizers and pesticides in irrigated agriculture, (ii) Increase in breeding
places for mosquitoes spreading Malaria/ Dengue, (iii) Salt-efflorescence-Salinity &
Alkalinity, (iv) Excessive seepage and water logging, (v) Damp climate resulting in marshy
land and low production, (vi) Revenue loss due to large subsidy in canal irrigation, (vii) Loss
of agricultural land due to construction of dams, reservoirs ,barrages, canal network, and
(viii) Shifting of cultural monuments, roads, railway lines, etc. from the reservoir area.

METHODS OF IRRIGATION:

(TECHNIQUES OF WATER APPLICATION/DISTRIBUTION ON FARMS):

Objectives:

(i) Adequate amount of water is stored in root zone of plants, (ii) Uniform application of
water is made possible, (iii) Minimum soil erosion takes place, (iv)Minimum wastage of
water, and (v) Re-use of water is made possible.

FACTORS AFFECTING CHOICE OF METHOD OF IRRIGATION:

(i) Soil characteristics of land to be irrigated, (ii) Slope and roughness of surface, (iii) Size of
stream supplying irrigation water, (iv) Available water supply and rate of advance, (v) Length
of run and time required to irrigate, (vi) Crop water requirement and growth type, (vii)
Infiltration rate of soil, (viii) Depth of root zone of plants, (ix) Depth of groundwater table,
(x) Possible erosion hazard, and (xi) Amount of water to be applied during each irrigation.
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1. Traditional Irrigation Methods:

(i) Uncontrolled or Wild Flooding,

(ii) Controlled or Free Flooding,

(iii) Border strip Irrigation,

(iv) Check Basin Irrigation,

(v) Ring/Basin Irrigation,

(vi) Furrow Irrigation,

(vii) Corrugation Irrigation, and

(viii) Sub-surface Irrigation.

2. Modern Irrigation Methods:

(ix) Sprinkler Irrigation,

(x) Drip/Trickle/Ooze Irrigation, and

(xi) Pot Irrigation Method.

1. Traditional Irrigation Methods:

(i) UNCONTROLLED OR WILD FLOODING: It is practiced where irrigation water is

abundant and inexpensive and the purpose of application of flood flows is to recharge the
crop root zone’s soil moisture to grow a crop after the flood season, or when the value of the
crop is small or the field is used for grazing. Water is spread or flooded over a rather smooth
flat land without much control or prior preparation. Crop lands are irrigated without regard to
efficiency or uniformity.

(ii) CONTROLLED /FREE FLOODING: Water is spread over the land, with proper methods
to control the depth of application. Water is stopped when it reaches other end of the plot.
Since the flow is not guided by ridges, there is wastage of water and does not ensure uniform
depth of irrigation.
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(iii) Border Strip Irrigation Method:

In border strip irrigation method, fields are divided into strips of different sizes. A boundary
called ‘Med’ is formed to separate the strips. These strips are constructed according to the
slope. The source of water is situated at the highest place in the field from where the whole
field can get the flow of water.

The width of strips is decided as per quantity of water. More wastage of water is caused if
strips are wider. Length of strip is decided by the slope of land and its structure. Effect of soil
composition is also visible on it.

Advantages:
1. It is possible to irrigate more area at a lesser expenditure.
2. It requires less labour.
3. Method of irrigation is easy and it causes lesser erosion.
Disadvantages:
1. It is not suitable for all types of crops.
2. It is not possible to get balanced supply of water.
3. It is not suitable for all soil compositions.
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From which dt= (y.dA)/(q-IA)

Considering I and y as constants and integrating, we get

t=- y/I [ln(q-IA)]0A =y/I[ln(q-IA)-ln q]

At t=0, A=0 and at t=t, A=A

t=2.303(y/I) log q/ (q-IA)

MAXIMUM AREA THAT CAN BE IRRIGATED FROM KNOWN ‘I’ AND ‘q’ VALUES:

log (q/(q-IA)=It/2.303y=x

10x=q / (q-IA)
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A= (10x-1)q/I.10x.I=q/I since (10x-1) / 10x =1

(iv) Check Basin Method:

In this method, the whole field is divided into small plots (basins) according to the capacity
of water. Basins are connected through a small drain type flow way, which has raised earthen
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walls on both sides. The flow way is of two types, one is the main and the other is connected
to basins. Sizes of basins are made according to the inflow of water.

The width of drains is affected by factors like flow of water, percentage, slope and structure
of the ground etc. The length of flow way is different depending on the basis of slope and
formation of the fields. This method is also prevalent in India as it does not cause any burden
on the farmer.

This method has the following advantages:

1. It is the best method of irrigation for levelled fields, like paddy fields.
2. It does not require any technical knowledge.
3. This method is more useful in soils having lesser infiltration.
4. In this method, rain water stays in basins; hence soil erosion is not caused.
5. It has lesser economic investment.
6. It irrigates more area.
7. Crops get sufficient water.

Following are disadvantages of check basin method:

1. Due to seepage in drains, wastage of water is caused.
2. Machines cannot be used in this method because during spray of insecticides or fertilizers,
the earthen walls of basins are damaged.
3. There is imbalance in distribution of labour. After growth of crops, water reaches the
basins in disproportionate quantity thereby causing wastage of water.
4. Creation of problem of water logging.
(v) Ring/Basin Irrigation Method:
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This irrigation method is more suited for horticulture development. In this method, a raised
platform called ‘Thala’ is formed as a ring around trees or bushes and they are connected
with each other through drains and the water reaches from one tree to the other. This method
is not suitable for crops.

Advantages:
1. It saves time. Once the inlet of water is opened, water reaches rings of other trees
automatically.
2. Its economic investment is less.
3. It is beneficial for more trees.
Disadvantages:
1. It is not useful for all crops.
2. Wastage of water is caused in it.
3. Diseases spread in trees.
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Furrow irrigation method is resorted to where crops are one grown in rows. Along the side of
rows of crops, ‘Dol’ is formed, and in between two such ‘Dols’, a furrow is formed in which
water flows for irrigation. The quantity of flow of water depends on demand of water by
plants and the rate of infiltration.
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In different situations, different furrow methods are used. They are mainly of five
Advantages:
1. Large areas can be irrigated at a time.
2. It saves labour since once the furrow is filled, it is not necessary to give water a second
time.
3. It is a comparatively cheaper method.
4. Plants get suitable quantity of water by this method.
Disadvantages:
1. Due to imbalance in flow of water, wastage of water is caused in it.
2. It is not suitable in all types of crops.
3. Making ‘Dol’ for drains requires more labour information.
4. Due to filling of excess water, there is risk of underground salts coming up to the surface
layer.
(vii) Corrugation Irrigation: This method is similar to the Furrow method of irrigation,
except that the size of corrugation is comparatively much smaller. Sugarcane is grown by
corrugation method.
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Sprinkler system consists of the pump to provide the needed pressure, the main pipe lines and
laterals, risers and sprinkler heads. Aluminium, polyethylene and steel pipes are used for the
mains and laterals. Riser pipes on which the sprinkler heads are mounted are made of mild
steel. Sprinkler heads are made of brass or other alloys. Based on the arrangements for
spraying irrigation water, the sprinkler irrigation system can be categorized as rotating head
system and perforated pipe system. The rotating head type system are classified as Portable
type, Semi-portable type, semi-permanent type, solid set type, Permanent system, and Centre
pivot system.
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Disadvantages of Sprinkler System of Irrigation:

(i) Wind may distort spreading of irrigation water from sprinkler system,

(ii) A constant water supply is needed for commercial use of sprinkler equipment system,

(iii) Water must be clean and free from sand, etc.

(iv) The power requirement is high, and

(v) Heavy soils with poor intake cannot be irrigated efficiently.

In present times, when water crisis is developing very fast everywhere, we should adopt
improved techniques of irrigation to encourage suitable water management. Sprinkler
irrigation method is an easy and simple method of irrigation in present times.

The whole land becomes available for cultivation of crops, whereas in traditional irrigation
methods, 15 to 20 per cent land remains vacant in depressions and boundaries. Modern
equipment’s can also be used in it due to absence of depressions and boundaries. Rate of
infiltration is higher in sandy soils where frequency of watering is more. Hence, sprinkler
irrigation method is more suited to sandy soils.

In sprinkler irrigation method, water is taken from source to the fields through pipes, whereas
in surface irrigation methods only 30-45 per cent water reaches the crops. Such loss of water
is avoided in sprinkler irrigation method. The problem of water logging may be caused in
case of excess water from surface irrigation, whereas no such problem is caused in sprinkler
irrigation method. The balance of groundwater is also maintained.

For development of sprinkler irrigation method, the following circumstances are

essential:
1. It is done in areas having scarcity of water.
2. Uneven ground level where irrigation is not possible by other irrigation methods.
3. Places having maximum temperature where crops might get destroyed, sprinkler irrigation
method maintains humid environment for the crops.
4 .Where soil textures may be of different nature, for example, sandy soil at some places and
stony soil at others places.
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5. It requires lesser number of labourers hence, it can be developed even where there are less
workers.
6. Irrigation may be required in large areas.
7. There should be average technical knowledge.
In areas where change in temperature of earth, environment and humidity is required for
growth of crops, sprinkler irrigation method is possible to a certain extent. Due to continuous
spray of water, there is improvement in physical conditions of earth and composition of soil.
In saline or reh soils, land can be improved by sprinkler irrigation, whereas surface irrigation
needs much more water for it.

Thus, it is a suitable irrigation method for sustainable development of water resources

in present times. It is installed in fields by three methods:
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In this case,
the whole arrangement is temporary and their places can be transferred as per requirement. In
this method, more irrigation is possible with lesser investment. It of course needs more
labour.
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Working System of Sprinkler Irrigation Method:

Due to different surface levels, location of tube wells and size of farm lands are different,
hence sprinkler irrigation method has not been considered as a suitable method in all cases.

While fixing sprinkler system on the farm, the following facts should be kept in mind:
1. The main pipeline of the sprinkler system should be fitted in the middle of the farm
towards the slope so that balanced irrigation is done on both the sides.
2. Branch pipeline should be fitted across the main line inversely to the slope.
3. Direction of the air should also be kept in view and it should be fitted at 90° of the
direction of the air but in no case it should be lesser than 45°.
4. Irrigation of crops needs to be done according to time hence, crops requiring water at
similar time should be sown near each other, so that extra labour is saved.
5. Even after changing the branch lines, the number of nozzles should remain same.
In sprinkler system, parts needed are pipe, nozzle, riser, coupler, bend, reducer, foot baton,
dot, etc. While erecting this equipment in the farm, there are two types of expenditure, i.e.
initial investment, and expenditure on maintenance of the set.

Initial investment depends on location of the tube well and area of the field. Maintenance is
more beneficial in case of tube well as compared to well and an engine. Initial expenditure is
55-60 per cent whereas maintenance expenditure ranges between 40-45 per cent.

The sprinkler set is kept according to the nature of the soil of the farm and on such basis is
decided duration between one and the other irrigation. In sandy soil, sprinkler set is kept at
one place for 3-4 hours and duration of 8-10 days is kept between the two irrigations.

As per soil, the time of keeping sprinkler at one place and duration between two
irrigations should be as under:
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Advantages:
1. There is increase in production and compactness.
2. It is helpful in soil conservation and stabilization of sand dunes in desert areas.
3. Sprinkler system is considered more suitable in areas where slit is coagulated on surface of
soil after rains, prevents growth of crop.
4. This system saves the crop from extreme frost or temperature.
5. Fertilizer application as well as insecticide spray can be done by sprinkler system.
6. Waste land can be improved by less water. Physical condition and composition of soil can
be maintained in a balanced condition by continuous sprinkling.
Disadvantages/Defects:
1. Sprinkler irrigation method is expensive.
2. It requires technical knowledge.
3. Sprinkler irrigation method cannot be used in all crops.
4. Crop is damaged by changing sprinkler system again and again.
5. Water to be used in sprinkler method should be clean.
In spite of the above defects, sprinkler irrigation method is being adopted with great speed
due to increasing water crisis.

(ii)Drip Irrigation:
A newly developed irrigation system known as drip irrigation or trickle irrigation, originally
developed in Israel, is becoming popular in areas of water scarcity. In this irrigation system, a
small amount of water is applied at frequent intervals in the form of water droplets through
perforations in plastic pipes or through nozzles attached to tubes spread over the soil to
irrigate a limited area around the plant.
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A precise amount of water equal to the daily consumptive use or the depleted soil water needs
to be applied. The soil water can be maintained at the field capacity during the crop growing
period. Deep percolation losses can be completely prevented and the evaporation loss is also
reduced.

The application of water and piping systems needs to be designed according to the type of
crops, topography and weather conditions typical to the geographical area.

The basic equipment for drip irrigation consists of a water supply head, a main pipe, lateral
pipes and drippers. The water flow in the pipe system is controlled with control valves and
fertilizers can be applied at the water source. As water passes through the very small outlets
of drippers, it is filtered before h is distributed in the pipe system.

Structure of Drip Irrigation Method:

The following are the main organs of drip irrigation method: water pump, main PVC,
pipeline, branch PVC pipeline connected to main line, plastic pipes connected to branch line,
drippers connected with plastic pipes, fertilizer tank for application of fertilizers, valve, water
measure, pressure controller, filter etc. Internal radius of side pipe is from 10 to 32 mm. Side
pipelines are fitted with drippers from where water falls in drops. Efficiency of drip irrigation
method depends on suitable operation of drippers. Flow rate of drippers is 2 to 10 litres per
hour.

This system of irrigation is established on the basis of type of crop, distance between plants,
requirement of water for crops and distance of water source from the field.
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Advantages:
1. In this method, water directly reaches the roots of the plants, which take water to plants in
balanced quantities.
2. Drip irrigation method saves 30 to 70 per cent water and it is possible to irrigate three
times more area with the same amount of water.
3. In this method, weeds do not spread because water reaches only near plants and does not
spread in the whole field.
4. Fertilizers and insecticides can also reach the plant directly by solution in the water and it
saves 30 to 60 per cent chemical fertilizers as well as 40 to 50 per cent pesticides along with
saving of water.
5. Even in case of uneven lands, drip irrigation method can do balanced irrigation.
6. Cultivation in saline and alkaline soil also can be done by this method of irrigation.
7. Crop production is higher by 20 to 40 per cent in drip irrigation method, because plants can
get air and water in required quantities, resulting in regular growth of crops.
8. Lesser labourers are required for irrigation work.
9. Bacteria causing diseases in crops do not grow because of dry atmosphere near plants.
Disadvantages:
1. Drip irrigation method is expensive.
2. It requires special technical knowledge for successful operation of this method.
3. In heavy soils, it creates problems of flow and water blockages.
4. Plants are able to get nutritive elements in a very limited area.
5. It is not suitable for every crop.
6. Utmost care has to be taken for holes of drippers, because soil may come along with water
at any time, which will prevent water dripping smoothing from holes.
7. Animals may cause damage to branch pipelines and dripper pipelines.
8. Most of the drippers work on pressure. Wherever land is sloppy, pressure on valves
increases by 50 to 10 per cent, which results in stoppage of working of valves on the upper
side.
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(iii) Pot Irrigation Method:

Pot irrigation method is more suitable for areas having scanty rainfall. In saline areas where
flow irrigation is not suited, pot irrigation method is successful. An earthen pitcher is used in
this method. The pitcher is fixed in the ground up to neck.

Holes are made in the pitcher and water is filled in it so that seepage of water through the
holes keeps the nearby soil moist. Water is filled in these pitchers at regular intervals. This
method can be considered as an alternative of drip irrigation method.

Pot irrigation method can be adopted in the following conditions:

1. Unlevelled land which is uneven.
2. Area having maximum shortage of water.
3. Such difficult areas where supply of fruits and vegetables is difficult and they are costly.
4. Where there is saline water, making surface irrigation difficult.
In this method, distribution of humidity around sides of pitcher is affected by many factors,
mainly size of the pitcher, seepage of water per unit of area and type of soil. Humidity is
spread in the same proportion as the size of the pitcher. Distance of pitcher also affects the
moist area. Normally, distance between two pitchers should be kept so much that the humid
area between them does not overlap.

Advantages:
1. In this method, only the area near the pot gets irrigated and not the whole area.
2. Evaporation of water is minimum in this method.
3. Water seepage below the ground is also in minimum quantity.
4. It is the best method for horticulture crops and vegetables.
5. Once the pitchers are fixed, irrigation can be done for six years, which reduces
expenditure.
6. It needs minimum technical knowledge.
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Defects:
1. Irrigation in this method is possible in a limited area.
2. This method requires clean water because unclean water would cause blockage of minor
holes, which would not be able to provide moisture any longer.
3. It is costly to draw out pitchers again and again and re-fix them.
4. It is not suitable for every crop.

DRIP/TRICKLE/OOZE/MICRO-IRRIGATION:

It is based on the basic concept of irrigating only the root zone of the crop, rather than the
entire land surface. Water flows from the emission points (nozzles) through the soil by
capillary and gravity. The soil moisture content of the crop root zone is maintained at near
optimum levels to facilitate optimum crop growth and production. This will involve frequent
applications of small quantities of water. Losses due to evaporation and percolation are
minimized. This method is highly economical and beneficial in acute water scarcity areas and
salt problem areas to grow orchards and plantation crops like coconut, tea, coffee,
cardamom, citrus, grapes, banana, papaya, mango, guava, pineapple, and watermelon; row
crops like sugarcane, cotton, groundnut, strawberry and vegetable crops like tomato, potato,
flower plants.

Drip irrigation system involves laying of system of head, mains, sub-mains, laterals and drop
nozzles. Water oozes out of these small drip nozzles uniformly at slow rate at depth of root
zone varying from 25 cm to 60 cm. Drip nozzles are fixed on laterals at regular interval of
about 0.5 meter to 1 meter discharging at very small rate of order of 2 two 10 litters per
hours.

Head consists of a pump to lift water so as to produce the pressure of about 2.5 atmosphere.
For proper flow of water through the system the lifted irrigation water is passed through
fertilizer tank, so as to mix the fertilizer directly in irrigation water and then through a filter
so as to remove the suspended particles in the water to avoid clogging of drip nozzles. Mains
and sub-mains are small size pipe made of flexible material like black PVC. These are buried
or laid on ground, their sizes be sufficient to carry design discharge of the system. Laterals
are very small sized, usually 1 cm to 1.3 cm diameter black PVC pipes taking off from mains
or sub-mains. Laterals can usually be up to 50 m long and one lateral line is laid for each row
of crops.

ADVANTAGES OF DRIP IRRIGATION: (i) 20% to 50% higher crop yield in fruit crops,
vegetable crops, and commercial crops due to maintenance of optimum soil moisture in crop
root zone throughout growing period of crop, (ii) Improved quality of harvested produce of
crop, (iii)) Savings in irrigation water, (iv) Increased efficiency in fertilizer use, (v) Reduced
energy consumption due to low operating pressure required, (vi) Tolerance to windy
atmospheric condition, (vii) Reduced labour cost, (viii) Better control of disease and pest
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control, (ix)Feasibility of irrigating undulating terrain and sloppy land, (x) Suitability for
common soils, (xi) Improved tolerance to salinity, (xii) Promotes congenial soil physical
condition in root zone, (xiii) Promote better infirmity in irrigation water application, (xiv)
Easy in operation, (iv) Facilitates automation, and (16) Adopted to irrigate crop in green
houses.

PROBLEMS IN DRIP IRRIGATION: (i) Emitter clogging, (ii) Restricted root development
of crops, (iii) Salt accumulation at the root zone periphery, (iv) Damage from rodents and
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other animals, (v) High cost system.

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Status of development of irrigation in India:

Irrigation potential & Actual Achievement:

As per report of the National Commission on Integrated Water Resources Development

(NCIWRD-1999), India has about 4% of the world’s fresh water resources. India receives an
average precipitation of about 1170 mm which corresponds to an annual precipitation 4000
BCM. There is considerable variation in precipitation both temporally and spatially. Nearly
75% of this i.e. 3000 BCM occurs during the monsoon season confined to 3 to 4 months in a
year. The more important fact is that average actual rainy days are ranging from 25 to 30 days
over a period of 4 year, conservation and management of this monsoon water is the key to
ensure food, water and energy security of the country. The average annual water availability
in the country is 1869 BCM. The remaining water is lost to the atmosphere through
evapotranspiration from barren lands, forests, natural vegetation, rain fed agriculture, natural
ponds, lakes, etc. It is estimated that owing to topographic, hydrological and other
constraints, the utilizable water with conventional approach is 1121 BCM which comprises of
690 BCM of surface water and 431 BCM of replenishable ground water resources.

The total ultimate irrigation potential (UIP) of the country is assessed as about 140 Million
hectare (Mha)). Recognising the importance of irrigation as a crucial input in India's
agricultural development, harnessing of water resources for irrigation has been given an
important place in our successive five-year Plans (FYP). The ultimate irrigation potential of
the country from major and medium projects is assessed at 58.5 million hectare (Mha). The
irrigation potential from minor projects is estimated at 55 Mha, which is undergoing
reassessment in view of the possible improvements in water management practices. As
against this, the irrigation potential created during the pre-plan period was 22.6 Mha. Further,
an estimated 62 Mha of additional irrigation potential has been created during 1951-96.
Consequently, up to 1996, 74.5 per cent of the total irrigation potential has been harnessed for
expanding irrigation facilities. Major and medium irrigation programmes accounted for 38
per cent of the additional irrigation potential created while the remaining 62 per cent of the
added irrigation potential came through minor irrigation programmes. Initially, starting from
I FYP, major and medium irrigation programmes contributed around two-third of the
additional irrigation potential created. Minor irrigation programmes contributed the
remaining one-third. This emphasis was gradually changing and completely reversed from IV
FYP onwards extending up to VIII FYP. As a result of this, both surface and ground water
resources were harnessed at varying levels across space and time with resultant variations in
their multiple impacts, which are highlighted later.

Irrigation development in India accounted for a financial outlay of Rs. 690 billion during I
FYP to VIII FYP. The outlay on irrigation includes major, medium and minor irrigation
projects and CADA but excludes the flood control programmes. The CADA was initiated in
1974/75 as a Centrally sponsored programme to ensure efficient utilisation of created
irrigation potential for optimising agricultural production from irrigated lands. The outlay on
minor irrigation projects includes both state and institutional sources but exclude private
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sources. Within minor irrigation projects, institutional sources accounted for nearly half of
the outlay during VIII FYP as compared to negligible level during I FYP. This shift in the
funding source from state to institutional source for supporting minor irrigation programmes
started almost from II FYP onwards and stabilised at around 50 per cent from IV FYP
onwards with only marginal variations. Such a shift in the funding source for minor irrigation
development also provided the fillip for increased share of minor irrigation in the additional
irrigation potential created from IV FYP onwards.

At all India level, canals dominated the source of irrigation with 41.5 per cent in 1972,
closely followed by wells with 38.7 per cent. However in 1982, wells became the dominating
source of irrigation with a share of 46.5 per cent, which further increased to 53 per cent in
1993. Consequently, the share of canals in the irrigated area has come down to 34.1 per cent
in 1993. Tanks as a source of irrigation also came down from 11.9 to 6.5 percent during the
period 1972-93.

Among the states, despite continuous decline in the share of canal irrigated area in the total
net irrigated area during this period, canals continued its domination as the major source of
irrigation in case of Andhra Pradesh, Haryana, Jammu and Kashmir, Karnataka, Orissa and
West Bengal. The share of canal irrigation in the net irrigated area has consistently declined
in every state during this period, 1972-93 excepting Gujarat, Himachal Pradesh, Karnataka
and Maharashtra.

In case of tanks as a source of irrigation, only Maharashtra has retained its share at around 15
per cent during this period. Every other state has recorded decline in the share of tanks in the
net irrigated area during 1972-93. Drastic decline in the tanks' share in irrigated area is
observed in Karnataka, Andhra Pradesh and West Bengal.

Orissa and West Bengal registered maximum increase in the share of wells as a source of
irrigation during 1972-93. The share in irrigated area by wells has more than doubled in
Andhra Pradesh and Bihar. Except in Gujarat and Maharashtra where the wells' share in
irrigated area has marginally declined, in most of the other states, this share has continuously
increased during this period.

Well-irrigated area has gone up from 6.7 Mha to 9.1 Mha during this period registering an
annual growth rate of 1.81 per cent. Tubewell irrigated area recorded an increase of around
10 Mha with an annual average growth rate of over 10 per cent. Relative to tubewell irrigated
area expansion; well irrigated area remained more or less stagnant during this period. Among
all farm holdings, least annual growth of around one per cent was observed in the marginal
farm holdings obviously because of unviable farm size to make capital investment in wells.
Large holdings of more than 10 ha registered marginal decline in the area irrigated by wells
during the same period.
26
 27

FUNCTIONS OF IRRIGATION WATER IN PLANT GROWTH:

(i) Provide essential moisture in the soil required for proper tillage of land, (ii) Provide
essential moisture required for proper germination of seed, (iii) Cool down the soil
temperature for proper germination of seeds, (iv) Act as solvent for nutrition present in soil
for absorption by roots through osmosis, (v) Activates useful bacteria to convert available
chemical compounds in soil into the forms usable by plants in association with air, (vi)
Activate some soils present in soil to provide nourishing food product, (vii) It washes out or
dilutes undesirable salts in soil, (viii) It saver plants from death because of frost action
during extreme winter, (ix) It provides humidity control required for tobacco, and (x) All
chemical and biological processes including photosynthesis require presence of water.
28
29
30
31
32
 33

Depth and frequency of irrigation:

Crop water requirement

It is essential to know the water requirement of a crop which is the total quantity of water
required from its sowing time up to harvest. Naturally different crops may have different
water requirements at different places of the same country, depending upon the climate, type
of soil, method of cultivation, effective rain etc.
The total water required for crop growth is not uniformly distributed over its entire life span
which is also called crop period. Actually, the watering stops same time before harvest and
the time duration from the first irrigation during sowing up to the last before harvest is called
base period. Though crop period is slightly more than the base period, they do not differ from
practical purposes. Figure 1
 34

indicates the relative usage of water for a typical crop during its entire growth period.
Sometimes, in the initial stages before the crop is sown, the land is very dry. In such cases,
the soil is moistened with water as t helps in sowing the crops. This is known as paleo
irrigation. A term kor watering is used to describe the watering given to a crop when the
plants are still young. It is usually the maximum single watering required, and other
waterings are done at usual intervals.
The total depth of water required to raise a crop over a unit area of land is usually called
delta. Some typical values of delta for common crops in some regions of India are as follows:
Rice
• 1000mm to 1500mm for heavy soils or high water table
• 1500mm to 2000mm for medium soils
• 2000 to 2500 for light soils or deep water table
• 1600mm for upland conditions

Wheat
• 250mm to 400mm in northern India
 35

• 500mm to 600mm in Central India

• Barley: 450mm

Maize
• 100mm during rainy season
• 500mm during winter season
• 900mm during summer season
• Cotton: 400 – 500mm

Sugarcane
• 1400mm to 1500mm in Bihar
• 1600mm to 1700mm in Andhra Pradesh
• 1700mm to 1800mm in Punjab
• 2200mm to 2400mm in Madhya Pradesh
• 2800mm to 3000mm in Maharashtra

This information has been gathered from the Handbook of Agriculture (fifth edition, 2000)
published by the Indian Council of Agricultural Research.

Duty of water
The term duty means the area of land that can be irrigated with unit volume of irrigation
water. Quantitatively, duty is defined as the area of land expressed in hectares that can be
irrigated with unit discharge, that is, 1 cumec flowing throughout the base period, expressed
in days.
Imagine a field growing a single crop having a base period B days and a Delta Δ mm which is
being supplied by a source located at the head (uppermost point) of the field, as shown in
Figures 2 and 3.
36
 37

The water being supplied may be through the diversion of river water through a canal, or it
could be using ground water by pumping (Figure 4).
Version 2 CE IIT, Kharagpur
 38

If the water supplied is just enough to raise the crop within D hectares of the field, then a
relationship may be found out amongst all the variables as:
Volume of water supplied = B*60*60*24 m3
Area of crop irrigated = D*104 m2
Volume of water supplied per unit area = D1000086400= DB64.8
Hence, knowing two of the three variables B, D and Δ the third party may be found out.
The duty of irrigation water depends upon a number of factors; some of the important ones
are as follows:
• Type of crop: As different crops require different amount of water for maturity, duties
are also required. The duty would vary inversely as the water requirement of crop.

• Climate season and type of soil: Some water applied to the field is expected to be lost
through evaporation and deep percolation.
 39

Evaporation loss has a direct bearing on the prevalent climate and percolation may be
during drier seasons when the water table is low and soil is also dry. Percolation loss
would be more for sandy soils than silty or clayey soils.

• Efficiency of cultivation methods: If the tillage and methods of water application are
faulty and less efficient, then the amount of water actually reaching the plant roots
would be less. Hence, for proper crop growth more water would be required than an
equivalent efficient system. Also, if the water is conveyed over long distances through
field channels before being finally applied to the field, then also the duty will rise due
to the losses taking place in the channels.

3.3.3 Crop growing seasons in India

Each crop has its own sowing and harvesting seasons and it is important to have a knowledge
of this which may help to decide the total water demand in a field having mixed crops.
In India, the northern and north eastern regions have two distinct cropping seasons. The first
coinciding mostly with the South western monsoon is called kharif , which spans mostly
from July to October. The other, called rabi, spans generally over October to March. The
summer season crops are planted sometime between April and June. In southern part of India,
there is no such distinct season, but each region has its own classification of seasons.
Generally, the kharif is characterized by a gradual fall in temperature, more numerous cloudy
days, low intensity, high relative humidity and cyclonic weather. During Rabi, there is a
gradual rise in temperature, bright sunshine, near absence of cloud days, and a lower relative
humidity.
The following table indicates some Season Local name Growing month
the regional cropping calendars in
India. State
Andhra Pradesh Kharif Serva or Abi July – December
Rabi Dalwa or Tabi December – April
Summer In limited areas March/April – June
Assam Pre-monsoon Ahu Mar/April–
June/july
- Sali June/July- Nov/Dec
- Boro Nov - May
Bihar Summer - March – July/Aug
Autumn - May/June–
Frequency of Irrigation

Irrigation frequency refers to the number of days between irrigation during periods
without rainfall. It depends on consumptive use of rate of a crop and on the amount of
available moisture in the crop root zone. It is function of crop, soil and climate. Sandy
soils must be irrigated more often than fine texture deep soils. A moisture use ratio
varies with the kind of crop and climate conditions and increases as crop grows larges
and days become longer and hotter.

In general, irrigation should start when about 50 percent and not over 60 percent of the
available moisture has been used from the root zone in which most of the roots are
concentrated. The stage of crop growth with reference to critical periods of growth is
also kept in view while designing irrigation frequency.
 40

The interval that can be safely allowed between two successive irrigations is known as
frequency of irrigation:

                                 Allowable soil moisture depletion

Irrigation interval = ---------------------------------------  
                                  Daily water use

Problem: Calculate irrigation interval when F.C=20.0% dry weight basis

PWP = 8.0 dry weight basis, BD = 1.4 g/cc
Root depth = 60cm   ET ratio = 0.5 cm/day

Allowable soil water depletion is equal to 25% of available soil water

                                            

Solution:

                                                   (20.0 – 8.0) X 1.40

                Available water    = ------------------------------- X 60
                                                           100
        
                                             = 10.08cm

                                                25 X 10.08          2.52

Allowable soil water depletion = ---------------- = -------- = 5.04 = 5 days
                                                  10.0                 0.5

Irrigation must be given at 5 days interval.

Irrigation efficiencies: Efficiency is the ratio of the water output to the water input, and
is usually expressed as percentage. Input minus output is losses. If losses are more, output is
less and, therefore, efficiency is less. Hence efficiency is inversely proportional to the losses.

(i) Efficiency of water-conveyance: It is the ratio of water delivered into the fields from the
outlet point of the channel, to the water entering into the channel at its starting point. I may be
represented by ɳc. It takes the conveyance or transit losses into consideration.

(ii) Efficiency of water application: It is the ratio of the quantity of water stored into the
root zone of the crops to the quantity of water actually delivered into the field. It may be
represented by ɳa. It may also be called on farm efficiency, as it takes into consideration the
water lost in the farm.

(iii) Efficiency of water storage: It is the ratio of water stored in the root zone during
irrigation (i.e. field capacity- existing moisture content). It may be expressed by ɳs.

(iv) Efficiency of water use: It is the ratio of the water beneficially used, including leaching
water, to the quantity of water delivered. It may be represented by ɳu.
 41

(v) Uniformity coefficient or Water distribution efficiency: The effectiveness of irrigation

may also be measured by its distribution efficiency, ɳd. It is defined below:

ɳd=[1-(d/D)] where D=Mean depth of water stored during irrigation.

d=Average of the absolute values of deviations from mean.

The water distribution efficiency represents the extent to which the water has penetrated to a
uniform depth, throughout the field. When the water has penetrated uniformly throughout the
field, the deviation from the mean depth is zero and the water distribution efficiency is 1.0.

Drainage of irrigated land:

In many irrigation projects, crop yields are reduced due to waterlogging and salinization of
the land. In some cases, there is total loss of production and therefore the land is abandoned.
Waterlogging may also cause human health problems, particularly malaria, because of
ponded water. Of the estimated 235 million ha of irrigated land in the world, 10 to 15 percent
has been affected by waterlogging and salinization.
Two important causes of waterlogging and salinization are: (a) excessive application
of irrigation water; and (b) lack of adequate drainage. Thus provision of adequate drainage is
a solution to the waterlogging and salinization problems of irrigated lands. However, it must
be pointed out that improving drainage should not be a substitute for reducing excessive
application and that improved drainage should not be implemented without first assessing
whether waterlogging may be reduced by optimizing application.

In the field, irrigation water, together with any rainfall, will be partly stored on the soil
surface and will partly infiltrate into the soil. If rain or irrigation continues for long
periods, pools may form on the soil surface. This excess water on the soil surface is called
ponded water. It needs to be removed.
Ponding is the accumulation of excess water on the soil surface.
Part of the water that infiltrates into the soil will be stored in the soil pores and will be used
by
the crop; another part of the water will be lost as deep percolation. When the
percolating water reaches that part of the soil which is saturated with water, it will cause the
water table to rise. If the water table reaches the root zone, the plants may suffer (Figure
3). The soil has become waterlogged. Drainage is needed to remove the excess water and
stop the rise of the water table.
Waterlogging is the accumulation of excess water in the root zone of the soil.
Even if irrigation water is of very good quality, it will contain some salts. So, bringing
irrigation water to a field also means bringing salts to that field. The irrigation water is used
by the crop or evaporates directly from the soil. The salts, however, are left behind (Figure 4).
This process is called salinization. If these salts accumulate in the soil, they will hamper the
growth of crops.
Salinization is the accumulation of soluble salts at the soil surface, or at some
point below the soil surface, to levels that have negative effects on plant growth
and/or on soils.
 42

Some crops are more tolerant to salts than others. Highly tolerant crops can
withstand a salt concentration up to 10 g/l in the saturation extract. Moderately tolerant crops
can withstand up to 5 g/l, and sensitive crops up to 2.5 g/l.
If sensitive crops are to be grown, drainage is needed to remove the salts.
So, drainage is used to control ponding at the soil surface, to control waterlogging in the
soil, and to avoid salinization.
Drainage is the removal of excess water and dissolved salts from the surface
and subsurface of the land in order to enhance crop growth.
Drainage can be either natural or artificial. Most areas have some natural drainage; this
means that excess water flows from the farmers' fields to swamps or to lakes and rivers.
Sometimes, however, the natural drainage is inadequate to remove the extra water or salts
brought in by irrigation. In such a case, an artificial or man-made drainage system is required.
A man-made drainage system is an artificial system of surface drains and/or subsurface
drains, related structures, and pumps (if any) to remove excess water from an area.
Therefore drainage is needed for successful irrigated agriculture because it controls
ponding, waterlogging and salinity.
DRAINAGE TO CONTROL PONDING
To remove ponding water from the surface of the land, surface drainage is used. Normally,
this consists of digging shallow open drains. To make it easier for the excess water to flow
towards these drains, the field is given an artificial slope. This is known as land shaping or
grading.
Surface drainage is the removal of excess water from the surface of the land by diverting
it into improved natural or constructed drains, supplemented, when necessary, by the
shaping and grading of the land surface towards such drains.
DRAINAGE TO CONTROL WATERLOGGING
To remove excess water from the root zone, subsurface drainage is used (Figure 6). This is
done by digging open drains or installing pipes, at depths varying from 1 to 3 m. The excess
water then flows down through the soil into these drains or pipes. In this way, the water table
can be controlled.
Subsurface drainage is the removal of excess water and dissolved salts from soils via
groundwater flow to the drains, so that the water table and root-zone salinity are controlled.
DRAINAGE TO CONTROL SALINIZATION
To remove salts from the soil, more irrigation water is applied to the field than the crops
require. This extra water infiltrates into the soil and percolates through the root zone. While
the water is percolating, it dissolves the salts in the soil and removes them through the
subsurface drains. This process, in which the water washes the salts out of the root
zone, is called leaching.
Leaching is the removal of soluble salts by water percolating through the soil.
The extra water required for leaching must be removed from the root zone by drainage,
otherwise the water table will rise and this will bring the salts back into the root zone.
Therefore salinity is controlled by a combination of irrigation and drainage.
BENEFITS OF DRAINAGE
One of the benefits of installing a drainage system to remove excess water is that the soil is
better aerated. This leads to a higher productivity of crop land or grassland because:
. The crops can root more deeply.
. The choice of crops is greater.
. There will be fewer weeds.
. Fertilizers will be used more efficiently.
. There will be less denitrification.
. The grass swards will be better.
 43

Other benefits of well-drained soils are:

. The land is more easily accessible.
. The land has a greater bearing capacity.
. The soil has a better workability and tilth.
. The period in which tillage operations can take place is longer.
. The activity of micro-fauna (e.g. earthworms) is increased, which improves permeability.
. The soil structure is better, which also improves permeability.
. Soil temperatures are higher, so that crops (particularly horticultural crops) and grasses
can be grown earlier.
When drainage makes it possible to control the water table, the benefits that follow are:
. The root zone cannot become salinized by the capillary rise of saline groundwater.
. Leaching is made possible.
In its turn, the benefits of leaching are:
. It prevents increases in soil salinity in the root zone, thus making irrigated land use
sustainable in the long term.
. By removing salts, it allows salt-sensitive crops, or a wider range of crops, to be grown.
. It makes it possible to reclaim salt-affected soils, thus bringing new land into cultivation.

COMPONENTS OF A DRAINAGE SYSTEM

As shown in Figure 8, a drainage system has three components:
. A field drainage system, which prevents ponding water on the field and/or controls the
water table.
. A main drainage system, which conveys the water away from the farm.
. An outlet, which is the point where the drainage water is led out of the area.
The field drainage system is a network that gathers the excess water from the land by
means of field drains, possibly supplemented by measures to promote the flow of water to
these drains.
The field drainage system is the most important component for the farmers. More details
on field drainage systems are given in the following section.
The main drainage system is a water-conveyance system that receives water from the
field drainage systems, surface runoff and groundwater flow, and transports it to the outlet
point.
The main drainage system consists of some collector drains and a main drainage canal. A
collector drain collects water from the field drains and carries it to the main drain for
disposal.
Collector drains can be either open drains or pipe drains.
The main drain is the principal drain of an area. It receives water from collector drains,
diversion drains, or interceptor drains (= drains intercepting surface flow or groundwater flow
from outside the area), and conveys this water to an outlet for disposal outside the area. The
main drain is often a canalized stream (i.e. an improved natural stream), which runs through
the lowest parts of the agricultural area (Figure 9).
The outlet is the terminal point of the entire drainage system, from where the drainage
water is discharged into a river, a lake, or a sea.
An outlet can be one of two kinds: a gravity outlet or a pumping station. A gravity outlet
is a drainage structure in an area which has outside water levels that rise and fall. There, the
drainage water can flow out when the outside water levels are low (Figure 10). In delta areas,
drainage by gravity is only possible for a few hours a day when tides are low. In the upstream
regions of a river, drainage by gravity might not be possible for several weeks, during periods
when river levels are high.
A pumping station is needed in areas where the water levels in the drainage system are
 44

lower than the water level of the river, lake or sea.

FIELD DRAINAGE SYSTEMS
A field drainage system can be a surface drainage system (to remove excess water from the
surface of the land) or a subsurface drainage system (to control the water table in the soil). In
surface drainage, field drains are shallow graded channels, usually with relatively flat side
slopes.
In subsurface drainage, field drains can be either open drains or pipe drains. Open drains
and pipe drains have the same function. The difference between them is the way they are
constructed: an open drain is an excavated ditch with an exposed water table; a
pipe drain is a buried pipe.
Surface drainage systems
A surface drainage system always has two components:
. Open field drains to collect the ponding water and divert it to the collector drain.
. Land forming to enhance the flow of water towards the field drains.
A surface drainage system is a system of drainage measures, such as open drains and
land forming, to prevent ponding by diverting excess surface water to a collector drain.
Land forming means changing the surface of the land to meet the requirements of surface
drainage or irrigation. There are three land-forming systems: bedding, land grading and land
planing.
Bedding:
Bedding is the oldest surface drainage practice. With this system, the land surface is formed
into beds. This work can be done by manual labour, animal traction, or farm tractors. The
beds are separated by parallel shallow, open field drains, oriented in the direction of the
greatest land slope (Figure 13). The water drains from the beds into the field drains, which
discharge into a collector drain constructed at the lower end of the field and at right angles to
the field drains.
Bedding is a surface drainage method achieved by ploughing land to form a series of low
beds, separated by parallel field drains.
The bedding system is normally used for grassland. In modern farming, bedding is not
considered an acceptable drainage practice for row crops, because rows near the field drains
will not drain satisfactorily. To overcome the disadvantages of the bedding system, the two
other methods of land forming have been developed: land grading and land planing.
Land grading:
Land grading for surface drainage consists of forming the land surface by cutting, filling and
smoothing it to predetermined grades, so that each row or surface slopes to a field drain. It is
a one-time operation.
Land grading for surface drainage differs from land levelling for irrigation in that, for
drainage, the grades need not be uniform. They can be varied as much as is needed to provide
drainage with the least amount of earthmoving.
Land grading is forming the surface of the land to predetermined grades, so that each row
or surface slopes to a field drain.
Compared with bedding, land grading reduces the number of field drains, thus reducing
the need for weed control and maintenance. Land grading also means that more land is
available for use.
Land planning
Land planning is the process of smoothing the land surface to eliminate minor depressions
and
irregularities, but without changing the general topography (Figure 15). It is often done after
land grading, because irregular micro-topography in a flat landscape, in combination with
heavy soils, can cause severe crop losses.
 45

Land planning is smoothing the land surface with a land plane to eliminate minor
depressions and irregularities without changing the general topography.
In the field, surface drainage systems can have two different layouts: the random field
drainage system, and the parallel field drainage system.
Random field drainage system
The random field drainage system is applied where there are a number of large but shallow
depressions in a field, but where a complete land-forming operation is not considered
necessary. The random field drainage system connects the depressions by means of a field
drain and evacuates the water into a collector drain (Figure 16). The system is often applied
on land which does not require intensive farming operations (e.g. pasture land) or where
mechanization is done with small equipment.
Parallel field drainage system
The parallel field drainage system (Figure 17), in combination with proper land forming, is
the most effective method of surface drainage. The parallel field drains collect the surface
runoff and discharge it into the collector drain. The spacing between the field drains depends
on the size of fields that can be prepared and harvested economically, on the tolerance of
crops to ponding, and on the amount and costs of land forming. The system is suitable in flat
areas with an irregular micro-topography and where farming operations require fields with
regular shapes.
Subsurface drainage systems
A subsurface drainage system is a system for the removal of excess water and dissolved salts
from the soil, using the groundwater as a "vehicle".
A subsurface drainage system is a man-made system that induces excess water and
dissolved salts to flow through the soil to pipes or open drains, from where it can be
evacuated.
If it is decided to install a subsurface drainage system, a choice has to be made between
open drains or pipe drains. Open drains have the advantage that they can receive overland
flow and can thus also serve as surface drainage. The disadvantages are the loss of land, the
interference with the irrigation system, the splitting up of the land into small farm blocks,
which hampers farming operations, and that they are a maintenance burden.
The choice between open drains or pipe drains has to be made at two levels: for field
drains and for collector drains. If the field drains are to be pipes, there are still two options for
the collectors:
. open drains, so that there is a singular pipe drainage system;
. pipe drains, so that there is a composite pipe drainage system.
In a singular pipe drainage system, each field pipe drain discharges into an open collector
drain.
A singular drainage system is a drainage system in which the field drains are buried
pipes and all field drains discharge into open collector drains.
In a composite system, the field pipe drains discharge into a pipe collector, which in turn
discharges into an open main drain. The collector system itself may be composite, with sub-
collectors and a main collector.
A composite drainage system is a drainage system in which all field drains and all collector
drains are buried pipes. For subsurface drainage, a distinction can also be made between
different types of systems. A random system connects scattered wet spots, often as a
composite system. If the drainage has to be uniform over the whole area, the drains are
installed in a regular pattern. This pattern can be either a parallel grid system, in which the
field drains join the collector drain at right angles (Figure 20B), or a herringbone system, in
which they join at sharp. Both regular
patterns may occur as singular or composite systems.
 46

Combined drainage systems

Sometimes, combined surface and subsurface drainage systems are used. Whether this is
needed or not depends on a combination of factors: the intensity and duration of the rainfall,
surface
storage, the infiltration rate, the hydraulic conductivity (which is a measure of the water
transmitting capacity of soils, , and the groundwater conditions. Some examples of combined
systems are:
. In irrigated areas in arid and semi-arid regions, where the cropping pattern includes rice
in rotation with "dry-foot" crops (e.g. maize and cotton), as in the Nile Delta in Egypt
. Subsurface drainage is needed to control salinity for the dry-foot crops,
whereas surface drainage is needed to evacuate the standing water from the rice fields
(e.g. before harvest).
Three layouts for a subsurface drainage system: (A) random system; (B) parallel grid
system;
(C) herringbone system
Areas with occasional high-intensity rainfall (say more than 50 mm/day), which causes
water to pond at the soil surface, even when a subsurface drainage system has been installed.
In both of these examples, the standing water could be removed by the subsurface drainage
system, but this would either take too long or require drain spacing that are so close
as to be economically unjustifiable. In such cases, it is generally more efficient to remove the
ponded water by surface drainage.

Command Area Development Program:

During the post-independence period high priority was accorded to increase agricultural
production and productivity for providing food security to the people and as such a number of
irrigation projects were constructed. The surface irrigation potential, which stood at 22.6
M.ha. till 1950-51 had increased to 33.6 M.ha. by mid-sixties. In the later years, it was
realized that the irrigation potential created was not being fully utilized and substantial gap
existed due to which the purpose of irrigation projects was not fully met. The gap between
irrigation potential created and irrigation potential utilized prompted the Irrigation
Commission in 1972 to make specific recommendations for systematic and integrated
development of commands of irrigation projects. Following this, a Committee of Ministers in
1973 suggested creation of a broad-based Area Development Authority for every major
irrigation project to undertake the work of comprehensive area development and
management. On the basis of the recommendations of the Committee of Ministers,
Government of India launched a Centrally Sponsored Scheme of Command Area
Development Programme in 1974-75. The primary objective of the CAD Programme has
been to bridge the gap between the irrigation potential created and that utilized through
increase in irrigated areas and thereon to increase efficient utilization of irrigation water and
improve the agricultural productivity in the irrigation commands. The programme envisaged
an integrated and co-ordinated approach to the development and management of command
 47

areas by constituting a multi-disciplinary team under the overall control of the Command
Area Development Authorities.

COMPONENTS OF THE PROGRAMME:

1. On-Farm Development (OFD) works:

(i) Development of field channels and field drains within the command of each Outlet

(ii) Land levelling on an outlet command basis

(iii) Reclamation of waterlogged areas (Since April 1996)

(iv) Enforcement of a proper system of "Warabandi" and fair distribution of water to

individual fields

(v) Realignment of field boundaries, wherever necessary

(where possible, consolidation of holding should also to be combined)

(vi) Supply of all inputs and services - including credit

(vii) Strengthening of extension services

(viii) Encouraging farmers for Participatory Irrigation Management (PIM)

2. Selection and introduction of suitable cropping pattern.

3. Development of ground water to supplement surface irrigation (conjunctive use

under Minor Irrigation sector).

4. Development and maintenance of the main and intermediate drainage system

(irrigation sector).

5. Modernisation, maintenance and efficient operation of the irrigation system up to the

outlet of one-cusec capacity (irrigation sector).

PROGRAMME COVERAGE

Beginning with 60 Major and Medium Irrigation Projects in 1974-75, the Programme now
covers 227 projects with a culturable command area of 22.16 million hectares spread over 23
States and 2 Union Territories.

PROGRAMME IMPLEMENTATION

The Command Area Development Wing of the Ministry of Water Resources coordinates and
monitors the implementation of the Command Area Development Programme at the national
level. Proposals received from the States for inclusion of new Projects under the Programme
are examined and, if found techno-economically feasible, are included under the Programme.
The progress is measured through physical and financial progress reports of the programme
as received from the States ; and, the quality of works is ensured through technical guidelines
 48

and suggestions provided to the State functionaries from time to time and through various
meetings, workshops, seminars etc. The programme is being implemented by the State
Governments through Command Area Development Authorities (CADAs) set up by them.
However, in some States, namely, Arunachal Pradesh, Himachal Pradesh, Meghalaya,
Nagaland, Tamil Nadu and Tripura, CAD Authorities have not been constituted and the
Programme is being administered through the line Departments concerned.

FINANCING PATTERN

The financing of the activities carried out under the Programme comes from the following
three sources viz; (i) State outlays; (ii) Central assistance on matching basis for certain
identified activities; and, (iii) Institutional finance. The financing pattern for providing the
Central Assistance to the States keeps on changing from Plan to Plan as per the past
experience. The financing pattern in force from April 1996 is, however, as follows:

1. Grants will be admissible on matching basis to the State Governments for the
‘establishment’, topographical and soil surveys, planning and design of OFD works,
supervision of OFD works, construction of field channels and field drains, enforcement of
Warabandi, adaptive trials, demonstration and training, crop compensation, subsidy to small
and marginal farmers on identified items, evaluation studies sponsored by the States,
reclamation of waterlogged areas and one-time functional grant to the Water Users’
Associations.

2. Cent per cent grant from the Central Government is given for orientation training for senior
level officers which is sponsored by the Central Government and also for evaluation studies,
if they are sponsored by the Central Government.

3. Subsidy will be admissible for land levelling and shaping, Ground Water development and
sprinkler and drip irrigation to small and marginal farmers for these items of work, on the
pattern followed under the Integrated Rural Development Programme (IRDP).

4. Loan for the purchase of equipment and machinery will be provided to the States on a
matching basis. FINANCIAL ACHIEVEMENTS An amount of Rs. 1980.57 crore has been
released as Central Assistance under the CAD Programme since its inception up to March,
1999. During the year 1998-99, an amount of Rs. 175.32 crore was spent against a Revised
Estimate of Rs. 176 crore. An outlay of Rs. 176.36 crore has been provided under the Central
Sector for implementation of the Programme during 1999- 2000 and Rs. 142.84 crore has
been released up to 02.03.2000.

PHYSICAL ACHIEVEMENT

The core components of physical works are construction of field channels and field drains,
implementation of warabandi (rotational water supply) and land levelling and shaping whose
achievements since inception to March 1999 are given below: -

Item of Work Target Anticipated Achievement

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1. Field channels 3.23 lakh ha. 145.02 lakh ha.

2. Field drains 0.65 lakh ha. 9.15 lakh ha.

3. Warabandi 3.34 lakh ha. 92.44 lakh ha.

4. Land levelling and shaping 0.23 lakh ha. 21.53 lakh ha.

The targets and anticipated achievements for the year 1999-2000 are as follows:-

Item of work Targets Anticipated achievements

1. Field channels: 2.23 lakh ha. 2.23 lakh ha.

2. Field drains: 0.22 lakh ha. 0.22 lakh ha.

3. Warabandi: 2.15 lakh ha. 2.15 lakh ha.

4. Land levelling and shaping: 0.30 lakh ha. 0.30 lakh ha.

GUIDELINES OF CAD&WM PROGRAMME DURING XII PLAN

1.0 Introduction

1.1 The Command Area Development and Water Management (CAD&WM) Programme has
to be implemented in a holistic manner pari-passu with irrigation project under Accelerated
Irrigation Benefits Programme (AIBP) so that irrigation potential created (IPC) with
hydraulic connectivity gets utilized soon after its creation, improves water use efficiency,
increases agricultural productivity and production and brings sustainability in the irrigated
agriculture in a participatory environment. All aspects of the CAD&WM Programme need be
taken up in an integrated and coordinated manner so as to achieve the envisaged objectives of
raising food grains production to meet the increasing need for growing population.

1.2 During XII Five Year Plan, following broad activities are to be covered under the
scheme: • Coverage of ongoing CAD&WM projects, completed/ on-going and new projects
and for Extension, Renovation & Modernization (ERM) of old CAD&WM projects; • At
least 10% of the CCA of each project under Micro-irrigation in lieu of OFD; • Survey,
planning, design and execution of On-Farm Development (OFD) works, construction of field,
intermediate & link drains, correction of system deficiencies and reclamation of waterlogged
areas; • Software activities like trainings, monitoring, evaluation, demonstration w.r.t. water
use efficiency and adaptive trials; • To provide one time functional grant & infrastructure
grant to registered Water Users’ Associations (WUAs) in project areas to be covered, • New
components to be taken up for mechanised land leveling in hilly areas & special category
States and laser leveling in selected areas; and • To provide one time central assistance to
WALMIs/IMTIs for strengthening of infrastructure.

2 2.0. Inclusion of Projects under approved CAD&WM Programme The inclusion criteria
will be as under: a) New Project proposals received in the Ministry of Water Resources after
technical examination by the Regional offices of CWC are to be considered in the Ministry
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and will be included with approval of the Secretary (WR). b) Any new project having
investment clearance by the Planning Commission on CAD&WM component of the project
and having provision in the State Budget will be eligible for inclusion under the Programme.
However, selection of projects from the bunch of projects received from the States will be
carried out subject to availability of funds under the scheme. However, projects receiving
central assistance under CAD&WM programme will not be allowed to be discontinued
abruptly without its completion /proper justification. c) The projects with micro-irrigation,
water audit, volumetric water distribution would get preference amongst the eligible projects
while consideration of inclusion. d) A Memorandum of Understanding (MoU) has to be
signed by the States to receive the central assistance as per the XII Five Year Plan.

3. Funding Pattern

3.1 The following components under CAD&WM Programme may be undertaken by the
States: Sl. No. Components Cost sharing1 between Centre and States a. Survey Planning and
Design 50 : 50 b. On-Farm-Development (OFD) works 50 : 50 c. Construction of Field,
Intermediate and Link Drains 50 : 50 d. Correction of system deficiencies 50 : 50 e.
Reclamation of Waterlogged Areas 50 : 50 f. (i) Functional grant to registered WUAs (ii)
Infrastructure grant to registered WUAs 45 : 45 75 : 25 g. Software components such as
demonstrations including on micro-irrigation, training, monitoring & evaluation, adaptive
trials 75 : 25 h. One time Grant to WALMIs/ IMTIs for strengthening of infrastructure (13
Nos.) 75 : 25 i. CAD&WM Establishment (limited to 10% of b,c,d & e) 50 : 50

Participatory Irrigation Management Program:

The concept of PIM though exists in the country for quite some time now but has not yet
blossomed. The National Water Policy - 2012 involves Water Users Associations in decision
making and participation in planning the project advocating WUAs to be entrusted with
statutory powers to collect and detain a portion of water charges, management volumetric
quantum of water allotted to them and maintain the distribution system in their jurisdiction.

Ministry of water Resources has been making efforts to promote farmers participation under
CADWM programme since 1987. The Ministry recognised the need for a legal framework in
the country and during 1998 circulated a Model Act to be adopted by the State Legislature for
enacting New Irrigation Acts/ amending existing Irrigation Acts. The legal framework
provides for creation of farmers organisations at different levels of irrigation systems. In
accordance with Model Act 17 States have enacted/ adopted Legislation for involvement of
farmers in irrigation management at different levels i.e. Water User Associations covering
cluster of outlets or a minor, distributary committee and project committee.

National Convention of Water User Association Presidents has been convened on 7th & 8th
November, 2014 with a vision to provide a platform for multi-stakeholders, consultation and
brain storming for making Water User Associations functionally effective, where they
already exist and creating an environment for establishing Water User Associations where
they are needed. The Agenda of the Convention has been so designed that it ensures
providing a free voice to farmers and Water User Associations enabling them to raise their
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concerns, limitations and challenges for making Water User Associations effective,
functional and enabling them to participate in evolving a viable solution to address them. The
Ministry envisages providing an open forum for the farmers and Water User Associations to
discuss candidly the role of Union Ministry, State Government and Water User Associations
at the Forum. Convening the National Level Convention is an initiating step for strengthening
Participatory Irrigation Management in the country.

PARTICIPATORY IRRIGATION MANAGEMENT (PIM)

The National Water Policy 1987 advocated involvement of farmers in the management of
irrigation. The irrigation potential increased nearly four times since the beginning of the
planned era but brought in several problems of management of irrigation in its wake. These
included unreliable and inequitable supply of water, especially at tail-end; improper O&M of
the systems, poor recovery of water rates, indiscipline in the distribution of water and the
problem of waterlogging due to seepage from canal network on the one hand and over
irrigation on the other. To address these problems it has been recognized that participation of
beneficiaries would help greatly for the optimum upkeep of irrigation system and utilization
of irrigation water. Keeping this aspect in view, PIM is a thrust area under the Programme
during the Ninth Five Year Plan period. The participation of farmers in the management of
irrigation would give responsibility for operation and maintenance and collection of water
rates from the areas under the jurisdiction of the Water Users’ Associations of concerned
hydraulic level. Under the CAD Programme, presently a provision is existing for a one-time
functional grant to farmers’ Associations @ Rs. 500 per hectare - of which, Rs. 225 per
hectare would be provided by the Central Government and, the State Governments each and
Rs. 50/- per hectare to be contributed by the Farmers’ Association. Government of Andhra
Pradesh and the Government of Goa have enacted legislations for the establishment of the
Water Users’ Associations. Other States are also in the process of taking steps in this
direction. About 27,000 Water Users’ Associations have been formed in various States
covering an area of about 60 lakh hectares, under different irrigation projects. The Ministry of
Water Resources have also facilitated setting up of a nongovernmental Organisation called
the Indian Network on Participatory Irrigation Management (IndiaNPIM) which will
disseminate relevant information about the PIM and promote its efficient implementation.

RECLAMATION OF WATER LOGGED AREAS

Water logging, soil salinity and alkalinity are mainly caused by unscientific management of
soil, water and crops in the irrigation projects. Obstruction of natural drainage, improper
upkeep of irrigation network, sluggish drainage are some of the other causes. To tackle this
problem, a new component "Reclamation of Waterlogged Areas in Irrigation Commands" has
been included under the CAD Programme since 01.04.1996 under which, 50 per cent Central
assistance in the form of grant is available to the States as per norms. Eighty proposals with
an estimated cost of Rs. 31.55 crore, covering an area of 29,492 hectares for reclamation of
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water logged areas in the irrigation commands in six States namely, Bihar, Jammu &
Kashmir, Karnataka, Kerala, Orissa and Uttar Pradesh have been approved recently and are
currently under various stages of implementation by the State Governments.