02. Methods of Irrigation.pdf

CE-402 Irrigation Engineering
1
02. Methods of Irrigation
B.Sc. Civil Engineering 8th Semester
Muhammad Ajmal (PhD)
Lecturer
Agri. Engg. Deptt.
Surface Irrigation Sprinkler Irrigation Drip Irrigation

Irrigation
Flow Irrigation Lift Irrigation
Perennial
Irrigation
Inundation
Irrigation
1. Direct Irrigation (River Canal Irrigation): Diversion Scheme
2. Storage Irrigation (Reservoir Irrigation): Storage Scheme
3. Combined Irrigation: Storage and diversion scheme
Methods of Irrigation
Based on Water Source

 Based on Water Application
Irrigation Methods
Surface
irrigation
Sprinkler
irrigation
Flooding
method
Furrow
method
Contour
farming
Wild flooding Controlled flooding
Free
flooding
Contour
laterals
Border
strips
Basin
flooding
Check
flooding
Zig-zag
method
Drip
irrigation
❖ Application of water to
crops may be of any of the
three basic methods

The basic requirement for adoption of any method are:
(i) Uniform distribution of 6-20 cm depth of water depending on the nature of
crops,
(ii) Economical conveyance structure,
(iii) Large discharge of water causing for reduction of conveyance losses, and
labour cost, and
(iv) Mechanised farming is possible

 Surface Irrigation
❖ Water is applied to the soil surface and the water flows by gravity either
through furrows, strips or basins.
❖ Water is applied from a channel located at the upper reach of the field.
❖ Loss of water by conveyance and deep percolation is high and the
efficiency of irrigation is only 40-50% at field level in this method of
irrigation.
❖ Controlled: Water is applied from the head ditch and guided by
corrugations, furrows, borders, or ridges.
❖ Uncontrolled: Wild flooding.

Common Types of Surface Irrigation
1. Furrow irrigation
2. Border irrigation
3. Basin irrigation

 Furrow Irrigation

❖In this method water is applied on the field is directed to flow through
narrow channels dug between the rows of crops, instead of distributing the
water throughout the whole field evenly.
❖The furrows must all have equal dimensions, in order to guarantee that the
water is distributed evenly.
❖Furrow irrigation is a cheap method in areas where water is inexpensive.
❖Suitable for mild slope and problematic in steep slope terrain's due to
erosion problem.

❖ Shape of furrows mainly depends on the type of soil and the size of the
stream
❖ Deep, narrow V-shaped furrow - suitable for sandy soil

❖ Wide, shallow furrow suitable for clay soil

➢ Shape and Spacing of Furrows:
❖Heights of ridges vary between 15 cm and 40 cm
❖ The range of spacing commonly used is from 0.3 to 1.8 m with 1.0 m as
the average.

➢ Shape and Spacing of Furrows:
❖Heights of ridges vary between 15 cm and 40 cm
❖ The range of spacing commonly used is from 0.3 to 1.8 m with 1.0 m as
the average.
❖Maximum slope for different soil types
Soil Type Maximum slopes*
Sand 0.25
Sandy loam 0.40
Fine sandy loam 0.50
Clay 2.50
Loam 6.25

 Border Irrigation

 In this method, parallel ridges are made to guide a sheet of flowing water when
the water moves down the slope.
 The field is divided into several long parallel strips called borders that are
separated by low ridges.
 Field should be even surface over which the water can flow down the slope with a
nearly uniform depth.
 Every strip is independently irrigated by turning a stream of water at the upper
end.

 Then water spreads and flows down the strip in a thin sheet.
 Water moves towards the lower end without erosion covering the entire width of
the border.
 Border method is suitable for most of the soils, while it is best suited for soils
having moderately low to high infiltration rates.
 However, it is not suitable for course sandy and clay textured soils.

 Basin Irrigation

 This method of irrigation is adopted mainly in orchards.
 Usually round basins are made for small trees and square basin for large trees.
 These basins allow more water to be impounded as the root zones of orchard plants are
usually very deep.
 Each basin is flooded and water is allowed to infiltrate into the soil.
 Based on type of crop and soil, nearly 5-10 cm depth of water may be needed for every
irrigation.
 The advantage of basin method is that unskilled labour can be used as there is no risk of
erosion.
 Disadvantages: there is difficulty in using modern machinery and it is also labour
intensive.
 Basin Irrigation

Size of Basins
 The size of basin is related to stream size and soil type
• Table : Suggested basin areas for different soil types and rates of water flow
Soil Type (areas is in hectares for each soil type)
Flow rate Sand Sandy loam Clay Clay-loam
• ………………………………………………………………………………………………………………………..
• l/s m3 /hr
• 30 108 0.02 0.06 0.12 0.20
• 60 216 0.04 0.12 0.24 0.40
• 90 324 0.06 0.18 0.36 0.60
• 120 432 0.08 0.24 0.48 0.80
• 150 540 0.10 0.30 0.60 1.00
• 180 648 0.12 0.36 0.72 1.20
• 210 756 0.14 0.42 0.84 1.40
• 240 864 0.16 0.48 0.96 1.60
• 300 1080 0.20 0.60 1.20 2.00
• Note: The size of basin for clays is 10 times that of sand as the infiltration rate for clay is low leading to higher
irrigation time. The size of basin also increases as the flow rate increases. The table is only a guide and
practical values from an area should be relied upon. There is the need for field evaluation.

 Free Flooding or Ordinary Flooding
 In this type of irrigation, ditches are excavated in field, either on contour (known as
contour flooding) or up and down known as free flooding.
 Water application on field with out levees is known as wild flooding and if levees are
available then it is called controlled flooding.
 Checks Flooding
 It similar to flooding method except flow is controlled by levees.
 Levees can be constructed along the contours or along the slope of a field.
 This method is suitable for permeable as well as less permeable soil.

 Contour farming

 Zig-zag Irrigation Method

 Sprinkler Irrigation
Methods Irrigation

❖ In this type of irrigation water is applied plants like natural rainfall.
❖ Water is distributed through a system of pipes usually by pumping.
❖ Water under pressure is carried and sprayed into the air above the crop through
a system of:
✓ Overhead perforated pipes, nozzle lines, or through nozzles fitted to riser pipes
attached to a system of pipes laid on the ground.
✓ Nozzles of fixed type or rotating under the pressure of water are set at suitable
intervals in the distribution pipes.
✓ Sprayed water wets both the crop and the soil and, hence, has a refreshing
effect.
❖ Water is applied at a rate less than the intake rate of soil so that there is no
runoff.
❖ Measured quantity of water is applied to meet the soil water depletion.
Sprinkler Irrigation

 Layout

 Suitability
❖ Sprinkler irrigation is suited for most row, field and tree crops and water can be
sprayed over or under the crop canopy.
❖ Large sprinklers are not recommended for irrigation of delicate crops such as
lettuce because the large water drops may damage the crop.
 Suitable slopes
❖ Sprinkler irrigation is adaptable to any farmable slope, whether uniform or
undulating.
❖ Lateral pipes supplying water to the sprinklers should always be laid out along
land contour.
❖ This will minimize the pressure changes at the sprinklers and provide a uniform
irrigation.

 Suitability
❖ Uniform application by “artificial rain”
❖ Good application efficiencies (0.7 – 0.8)
❖ Dependent on wind, temperature, humidity
❖ Fairly terrain independent (but design must take terrain into account)
❖ Can have a low labor content
However,
❖ More initial cost
❖ High maintenance cost due to pumping
❖ Can be complex to run

 In this irrigation system:
❖ Water is applied directly to the crop ie. entire field is not wetted.
❖ Water is conserved
❖ Weeds are controlled because only the places getting water can grow weeds.
❖ There is a low pressure system.
❖ There is a slow rate of water application somewhat matching the consumptive
use. Application rate can be as low as 1 - 12 l/hr.
❖ There is reduced evaporation, only potential transpiration is considered.
❖ There is no need for a drainage system.
Drip or Trickle Irrigation

 In this irrigation system:
❖ Water is applied close to plants so that only part of the soil in which the roots
grow is wetted i.e. entire field is not wetted.
❖ Water is conserved
❖ Weeds are controlled because only the places getting water can grow weeds.
❖ There is a low pressure system.
❖ There is a slow rate of water application somewhat matching the consumptive
use.
❖ Application rate can be as low as 1 - 12 l/hr.
❖ There is reduced evaporation, only potential transpiration is considered.
❖ There is no need for a drainage system.

 Suitability
❖ Drip irrigation is adaptable to any farmable slope.
❖ Normally the crop would be planted along contour lines and the water supply
pipes (laterals) would be laid along the contour also.
❖ This is done to minimize changes in emitter discharge as a result of land
elevation changes.
❖ Drip irrigation is suitable for most soils.
❖ On clay soils water must be applied slowly to avoid surface water ponding
and runoff.
❖ On sandy soils higher emitter discharge rates will be needed to ensure
adequate lateral wetting of the soil.

 Suitability
❖ One of the main problems with drip irrigation is blockage of the emitters.
❖ All emitters have very small waterways ranging from 0.2-2.0 mm in diameter
and these can become blocked if the water is not clean.
❖ Thus it is essential for irrigation water to be free of sediments.
❖ ]If this is not so then filtration of the irrigation water will be needed.
❖ Blockage may also occur if the water contains algae, fertilizer deposits and
dissolved chemicals which precipitate such as Ca and Fe.
❖ Filtration may remove some of the materials but the problem may be complex
to solve and requires an experienced professional.

35
Least Efficient
Most Efficient
Flood Irrigation
Furrow Irrigation
Basin Irrigation
Drip Irrigation
Efficiency of Irrigation Methods

02. Methods of Irrigation.pdf

Recommended

Recommended

More Related Content

Similar to 02. Methods of Irrigation.pdf

Similar to 02. Methods of Irrigation.pdf (20)

More from MuhammadAjmal326519

More from MuhammadAjmal326519 (20)

Recently uploaded

Recently uploaded (20)

02. Methods of Irrigation.pdf