3. DEFINITION
• Irrigation – Supply of water by artificial methods to the fields for
cultivating the crops.
• IE – controlling and harnessing various natural sources of water -
dams, reservoirs, canals and headworks – distributing water to
agricultural fields
4. NECESSITY OF IRRIGATION
• India – agricultural country, resources depends on agricultural output.
• Rainfall – ill-timed or insufficient.
• Maximum yield – supply optimum quantity of water & maintain
correct timing.
• Systematic irrigation system – collecting water during excess rainfall
and releasing when needed.
5.
6.
7. NECESSITY OF IRRIGATION
1) Less rainfall
• Total rainfall less than needed for crops – artificial supply necessary.
• Irrigation work constructed at place where water is available – convey
to area with deficiency.
• Eg: Rajasthan canal – arid zones with 100-200mm rainfall.
8. NECESSITY OF IRRIGATION
2) Non – uniform rainfall
• Rainfall not uniform during crop period.
• Rain available at early period of crop, not available at the end – yield
• Collection of water during this excess period, stored and supplied at the
deficient period.
• Eg; rainfall during winter is scarce – artificial supply.
9. NECESSITY OF IRRIGATION
3) Commercial crops with additional water
• Rainfall sufficient for usual crops.
• Commercial and cash crops may need additional water eg- sugar cane.
4) Increase in cultivable areas
• Areas with nominal rainfall prone to draught conditions.
• Irrigation of such areas increases the cultivability of land.
10. PURPOSE OF IRRIGATION
• Adds water to soil – increasing soil moisture.
• Saves crops from drying during droughts.
• Cools soil and atmosphere – favourable for plant growth.
• Washes/dilutes salts in soil
• Reduces hazard of soil piping
• Softens tillage pans.
11. SCOPE OF IRRIGATION ENGINEERING
• Engineering aspects-
• Storage, diversion & lifting of water.
• Conveyance of water to agricultural fields.
• Application of water to agricultural fields.
• Drainage and relieving water logging.
• Development of power.
13. SCOPE OF IRRIGATION ENGINEERING
• Agricultural aspect
• Proper depth of water in single application of water
• Distribution of water uniformly and periodically.
• Capacities of different soil for irrigation water & flow of water in soils
• Reclamation of waste and alkaline lands.
14. ADVANTAGES OF IRRIGATION
1) Increase in food production
• Controlled and timely supply of water – yield is increased.
• Assured supply of water – superior crops are cultivated, value of crops are
increased.
• Optimum quantity of water for a crop determined experimentally and
applied scientifically on field.
15. ADVANTAGES OF IRRIGATION
2) Protection from famine
• Construction of irrigation works helps during famine and drought.
• During construction of irrigation employment is created providing relief
during famine.
• After construction, continuous water supply is maintained during drought.
3) Cultivation of cash crops
• Irrigation helps in cultivation of water intense cash crops such as sugar cane,
indigo, tobacco, cotton.
16. ADVANTAGES OF IRRIGATION
4) Addition to wealth of the country
• Irrigation projects generate revenue to the state.
• Water tax is collected from the farmers
• Increased crop production due to irrigation – self – sufficient in food
requirement, saving foreign exchange.
5) Increase in prosperity of people
• Due to irrigation facility – value of land is increased.
• Increase in yield of crops, ability to grow cash crops – living standards are
improved.
17. ADVANTAGES OF IRRIGATION
6) Generation of Hydro – Electric Power
• Major river valley Irrigation projects planned for hydro electric power.
• Falls on irrigation channels can be utilised to generate electricity.
7) Domestic and industrial water supply
• Irrigation reservoirs also supply water to nearby urban and rural areas.
• Canals provide facilities for bathing, cattle watering, boating etc.,
8) Inland navigation
• Large canals can be used for inland navigation, easy transportation of
agricultural products to the market.
18. ADVANTAGES OF IRRIGATION
9) Improvements of Communication.
• Irrigation channels are provided with inspection roads.
• Paving the roads helps in increased communication, accessibility to rural areas.
10) Canal Plantations
• Trees can be planted along the banks of the canals, water courses and field
boundaries. This improves the timber wealth of the country and environment.
11) Improvements in ground water storage
• Due to constant percolation and seepage, ground water table is raised in irrigated
areas. (but GWT must not reach root zone)
19. DISADVANTAGES OF IRRIGATION
1) Breeding place for mosquitoes.
• Excess application & leakages depressions filled with water – breeding place
for mosquitoes.
2) Water logging
• GWT near ground surface, over irrigation leads to rise in GWT. Saturates the
root zone, causes efflorescence & results in water logged area.
3) Damp climate
• Areas which are damp and cold becomes more damper and colder due to
irrigation.
21. TYPES OF IRRIGATION
Broad classification:
- Surface irrigation
- Subsurface irrigation
Water available at higher level supplied to lands on lower level via gravity
through canals - Flow irrigation
Water available at lower level lifted via mechanical means to supply water on
higher level land- Lift irrigation
