IT GIVES AN IDEA OF IRRIGATION ENGINEERING

1. IRRIGATION
UNIT-III
Preparedby
P DIVAKAR
Assistant Professor

2. IRRIGATION
It may be defined as the process of artificially supplying water to soil for raising crops.

3. NECESSITY OF IRRIGATION
• Less rainfall
• Non-uniform rainfall
• Growing a number of crops during a year
• Growing perennial crops
• Commercial crops with additional water
• Controlled water supply

4. Advantage of
irrigation
• It can significantly increase crop yields,
improve crop quality, and enhance
agricultural productivity.
• It allows farmers to control the timing,
frequency, and amount of water applied to
crops, which can optimize plant growth and
development.
• It can support the cultivation of a wide range
of crops, including those that require large
amounts of water, such as rice and
sugarcane.
• It washes out or dilutes salts in the soil

5. ILL-EFFECTS OF
IRRIGATION
• Breeding places for mosquitoes
• Water logging
• Damp climate

6. TYPES OF IRRIGATION

7. FLOW IRRIGATION
• Water is allowed to flow over the soil surface and soak into the ground by gravity.
This type of irrigation is also known as surface irrigation.

8. PERENNIAL
IRRIGATION
• It is a type of irrigation system that
provides a continuous and reliable
water supply to crops throughout
the year, regardless of the season
or weather conditions.
• In this system some storage head
works, such as dams and
storage weirs or barrages are
required to store the excess water
during floods and release it to
crop as and when it is required

9. INUNDATION
IRRIGATION
• It is carried out by deep flooding
and thoroughsaturationof the
land to be cultivatedwhich is then
drained off prior to the planting of
the crop

10. FLOW IRRIGATION
• Depending upon the source from which the water is drawn flow irrigation can be further
subdivided into three types:
• Direct irrigation (River canal irrigation)
• Storage irrigation (storage scheme)
• Combined storage and diversion scheme

11. DIRECT
IRRIGATION
• The water is directly diverted to the
canal without attempting to store
the water.
• For such a system, a low diversion
weir or diversion barrage is
constructed across the river
• This raises the water level in the
river and thus diverts the water to
the canal taking off upstream of the
weir
• It is a smaller magnitude compared
to other

13. STORAGE IRRIGATION
• A solid barrier such as a dam or a storage weir
is constructedacross the river and water is
stored in the reservoir or lake so formed.
• Depending upon the following the
storagevolume is decided
• Water requirement of crops
• Hydroelectricity power generation
• Flow of water in the river
• It is comparatively of a bigger magnitude and
involves much more expenditure than a direct
irrigation scheme

15. COMBINED SYSTEM
• In this system a combined scheme is adopted in which the water is first stored in the reservoir
formed at the upstream side of the dam and this water is used for water power generation
• After that the water is flows in down-stream of the dam again the water is diverted by
constructing a weir or barrage

17. LIFT IRRIGATION
• The water supply is at too low a level to run by gravitation on to the land
• In such circumstances water is lifted up by mechanical means
• Irrigation from wells is an example of lift irrigation, in which sub-soil water is lifted up to the
surface and is then conveyed to the agricultural fields

18. METHODS OF APPLICATION OF IRRIGATIONWATER

19. WILD FLOODING
• Water is spread or flooded on a rather
smooth flat land, without much
control or prior preparation
• This method is generally used in the
inundation irrigation system in which
water is forced to spread over vast
tracts during the season of high stream
flow
• It is wasteful use of water
• It is practiced largely where irrigation
water is abundant and inexpensive

20. FREE FLOODING
• It is a controlled floodingirrigation method
• Water is spread over the land,with proper
methods to control the depth ofapplication
• It consists of dividingthe entire land to be
irrigated into small strips bya number of
field channels known as laterals
• It will construct right angles to the sides of
the field or right angles to the contour lines
• And provides supplychannel to supply
water for irrigation and waste channels
situated for collectingexcess waste from
the laterals
• Use for flat/steep lands.

22. FLOODING BY CONTOUR LATERALS
• This is a special case of free flooding in which the field channels or laterals are aligned
approximately along the contour lines
• It is applicable for steeper terrain

24. BORDER STRIPS
FLOODING
• The farm is divided into a series of strips 10 to
20m wide and 100 to 300m long
• These strips are separated by low levees or
borders and run down the predominant or
any other desired slope

26. CHECK FLOODING
• It similar to free flooding except that the water is controlled by surrounding the check area
with low, flat levees surrounding each check while in free flooding no such levees are
provided and strips are divided by field channels
• It is the mostcommon method used in India
• The method is also known as irrigation by plots since the entire area is divided into several
plots obtained by subdividing the entire area by levees

28. ZIG-ZAG METHOD
OF FLOODING
• It is special method of flooding where water
takes circuitous route before reaching the
dead end of each plot
• The whole area is divided into a number of
square or rectangular plots; each plot is then
subdivided with the help of low bunds or
levees
• It is suitablefor level plots
• It is highly unsuitable for farming operations
with modern farm machinery

30. FURROW
METHOD
• It is used for row crops like
maize, jowar, sugarcane, cotton,
tobacco, groundnut, potatoes
etc.
• A furrow consists of a narrow
ditch between rows of plants
• Commonly the length of furrow
is adopt 100 to 200 m

32. CONTOUR
FARMING
• Contour farming is a soil conservation
technique that involves cultivating
crops along the contours of the land.
• The primary objective of contour
farming is to reduce soil erosion by
slowing down the flow of water across
the land.
• Contour farming helps in conserving
soil fertility, retaining moisture, and
minimizing water runoff.

33. SUB-SURFACE IRRIGATION
• It consists of supplying water directly to the root zone of the crop.
• Following are the favorable conditions for the sub-surface irrigation
• Existence of high water table
• Permeable soil such as loam or sandy loam in the root zone of the soil
• Uniform topographic conditions
• Moderate slopes
• Good quality irrigation water
• It may be of two classes:
• Natural sub-irrigation
• Artificial sub-irrigation

34. NATURAL SUB-IRRIGATION
• Water is suppliedto the root zone of the plantsby controllingthe level of localwater table
• Such a high level of water table in the area may be available due to water seeping from earthen canals,
drains, rivers etc.
• In order to maintain the ensure the requisite supply of water to the root zone it is essential to maintain the
desired water level by artificial means.

35. ARTIFICIAL SUB-
IRRIGATION
• Supplying water directly to the root zone of
crops through a network of buried perforated
pipes
• Water is made to pass under pressure,
through these underground perforated pipes
• It suitable only for the conditions of high
horizontal permeability and low vertical
permeability so that percolation losses are
minimized
• The pipes are buried 0.3 to 0.4 m deep and
spaced 0.4 to 0.5 m horizontally for uniform
distribution of water

36. SPRINKLER
IRRIGATION
• Itconsists of applying the water in the
formof a spray
• This method is moreusefulwhere:
• The land cannotbe prepared for
surfacemethods
• Slopes are excessive
• Topography is irregular
• Soil is erosive
• Soil is excessively permeable or
impermeable
• The cost of land preparation is less but
initial investmentis high in the purchase
of the appurtenances

37. TYPES OF
SPRINKLERS
• Fixed nozzle pipe system
• Perforated pipe system
• Rotating sprinklers system

38. DRIP IRRIGATION
• It is also known as trickle irrigation, water is
applied in the form of drops directly near the
base of the plant
• This technique also known as feeding bottle
technique where by the soil is maintained in
the most congenital form by keeping the soil
water air proportions in the optimum range
• It is firstly introduced by Israel
• This type of irrigation is suitable for vegetable
crops such as tomatoes, peppers, cucumbers,
lettuce, and carrots, field crops like corn,
soybeans, wheat, and cotton.

39. Arrangement for Drip irrigationsystem

40. Advantages of drip
irrigation
• Less requirement of irrigation water
• Water supply at optimum level
• Water logging avoided
• High yield
• Cultivation of cash crops
• No soil erosion
• Suitable for any topography

41. QUALITY OF IRRIGATION WATER
• pH Level: Impact on nutrient availability and plant growth
• Salinity: Effects on water uptake and crop yield
• Total Dissolved Solids (TDS): Influence on crop growth and quality
• Specific Ion Concentrations: Impact on soil and plant health
• Toxic Elements: Risks to plant growth and human health
• Organic Contaminants:Effects and safety compliance
• Microbial Contamination: Risks, testing, and mitigation
• Water Availability: Impact on salt concentration and contaminants
• Water Sources: Evaluation of water quality based on source
• Water Treatment and Management: Techniques for improving
water quality

42. CLASSIFICATION OF IRRIGATION WATER
• Classification based on total concentration of soluble salts
• Classification based on sodium concentration
• Classification based on electrical conductivity (EC), total salt content
(TDS), sodium concentration (ESP), boron concentration etc.

43. CLASSIFICATION BASED ON TOTAL
CONCENTRATION OF SOLUBLE SALTS
• Irrigation watermay containvarioustypes of salts such as sodium, calcium, magnesium and potassium etc.
• Those salts may prove to be injuriousto the crops
• Excess quantityof these salts reduce the osmotic activity of the plants, thus preventingthe absorptionof
nutrientsfrom the soil
• It is expressed in
• parts per million (ppm) or milligram per liter (mg/l)
• Milli equivalents per liter (meq/l)
• Electrical conductivity (mS/cm or micro-mhos/cm)
• The salinityconcentrationof soil solution(Cs)
C = conc. of salts in irrigationwater
Q = totalquantityof water appliedto the soil
Cu = consumptive use of water
Peff = useful rainfall

45. CLASSIFICATION BASED ON SODIUM
CONCENTRATION
• If the % of sodium is more, the aggregation of soil grains break down and the soil
becomes less permeable
• Even on sandy soils, water of 85% sodium or higher are likely to make soil
impermeable after prolonged use
• Constant irrigation with high sodium water, the soil becomes plastic and sticky
when wet and forms clods and crust on drying
• Irrigation water is classified on sodium concentration on the basis of a factor
called sodium absorption ratio (SAR)

47. CLASSIFICATION BASED ON ELECTRICAL CONDUCTIVITY (EC), TOTAL SALT
CONTENT (TDS), SODIUM CONCENTRATION (ESP), BORON CONCENTRATION ETC.
• Class 1 water are considered to be excellent for most of the plants.
• Class 2 waters are considered as good to injurious, probably harmful
to more sensitive crops
• Class 3 waters are considered unsuitable under most conditions

48. BASE PERIOD
• It is the time elapsed between first watering and last watering to a
given field of irrigation

49. Crop period
• It is the time elapsed between the instant of sowing and the instant
of harvesting

50. DUTY
• Duty of water is defined as area of land irrigated per unit discharge of water
• For example: if 1000 ha of land can be irrigated for growing any crop by supplying
1 cumec of water continuously for the entire base period of the crop then duty of
water for this crop is said to be 1000 ha/cumec
A = area in ha
Q = discharge in cumec
D = duty in ha/cumec

51. DELTA
• It is the total depth of water required by a crop to be supplied during
its base period to come to maturity.
• This Δ water will be supplied with proper distribution over the base
period of crop depending upon crop requirements.

52. DUTY AT VARIOUS
PLACES
• Duty of water varies from place to place, because of
continuous conveyance losses as the water flow; it is
minimum at source and maximum at the utilization point
(field)
• At the head of main canal --- known as Gross quantity
• At the head of branch canal --- known as Lateral quantity
• At the outlet of a canal --- known as outlet factor
• At the head of land to be irrigated ---- known as Net
quantity

54. UNITS OF VOLUME OF IRRIGATION WATER
• ha-m = 10,000 m2 x 1 m
= 10,000 m3
• Cumec-day = 1m3/s x 1 day
= 1m3/s x 86400 s
= 86400 m3
1 Cumec-day = 8.64 ha-m

55. RELATION BETWEEN DUTY AND DELTA
Consider an irrigation field of area D hectares, with water application for a depth of Δ meter volume of water delivered to the
total field
= DΔ ha-m
= DΔ x 104 m3 ----(1)
This water volume is nothing but supply of water to the field at the rate of 1 cumec for a period of B days. ie
= 1 (B) cumec-days
= 1 x B x 24 x 60 x 60 m3 ----- (2)
From equation (1) and (2)
D(Δ ) 104 = B x 24 x 60 x 60
D = duty in hectares/cumec
Δ = total depth of water supplied (in m)
B = baseperiod in days

56. FACTORS AFFECTING
DUTY
• Methodsof irrigation
• Mode of applyingwater to the crops
• Method of cultivation
• Time and frequency of tilling
• Type of the crop
• Base period of the crop
• Climaticconditionsof the area
• Quality of water
• Method of assessment of irrigationmethod
• Canalconditions
• Characterof soil and sub-soil of the canal
• Characterof soil and sub-soil of the irrigationfields

57. METHODS OF IMPROVING
DUTY
• The land should be properly ploughed and levelled
before sowing the crops
• Suitablemethod of applicationof water to the
crops
• Lined canalsmust be used
• Rotationof crops must be practiced
• Volumetric method of assessment must be used
• Farmers must be given proper training so that
moisture contentof the field should not exceed
field capacity
• Canalalignment should be in sandy soil
• Frequent cultivationof the land must be adopted

58. THANK YOU