02. Methods Of Irrigation 1q2p4w

CE-402 Irrigation Engineering

02. Methods of Irrigation B.Sc. Civil Engineering 8th Semester Muhammad Ajmal (PhD) Lecturer Agri. Engg. Deptt.

Surface Irrigation

Sprinkler Irrigation

1

Drip Irrigation

Methods of Irrigation Based on Water Source Irrigation

Lift Irrigation

Flow 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 Application  Application of water to crops may be of any of the three basic methods

Irrigation Methods

Flooding Furrow method method

Wild flooding

Sprinkler irrigation

Surface irrigation

Drip irrigation

Contour farming

Controlled flooding

Contour Free flooding laterals

Border Check Basin strips flooding flooding

Zig-zag method

Methods of Irrigation 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

Methods of Irrigation  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

Common Types of Surface Irrigation  Furrow Irrigation

Common Types of Surface 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.

Common Types of Surface Irrigation  Furrow Irrigation

Common Types of Surface Irrigation  Furrow Irrigation

Common Types of Surface Irrigation  Furrow Irrigation  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

Common Types of Surface Irrigation  Furrow Irrigation  Wide, shallow furrow suitable for clay soil

Common Types of Surface Irrigation  Furrow Irrigation  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.

Common Types of Surface Irrigation  Furrow Irrigation  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

Common Types of Surface Irrigation  Border Irrigation

Common Types of Surface Irrigation  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.

Common Types of Surface Irrigation  Border Irrigation  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.

Common Types of Surface Irrigation  Border Irrigation

Common Types of Surface Irrigation  Basin Irrigation

Common Types of Surface Irrigation  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.

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.

Common Types of Surface Irrigation  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.

Common Types of Surface Irrigation  Contour farming

Common Types of Surface Irrigation  Zig-zag Irrigation Method

Methods Irrigation  Sprinkler Irrigation

Sprinkler 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

Sprinkler Irrigation  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.

Sprinkler 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 )  Can have a low labor content

However,  More initial cost  High maintenance cost due to pumping  Can be complex to run

Drip or Trickle Irrigation

Drip or Trickle Irrigation  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.

Drip or Trickle Irrigation  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.

Drip or Trickle Irrigation  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.

Efficiency of Irrigation Methods Least Efficient Flood Irrigation Furrow Irrigation Basin Irrigation Sprinkler Irrigation Drip Irrigation

Most Efficient 35

Questions?