What is irrigation ?
Irrigation was defined as the supply of water by artificial methods to the field for cultivating the crops.
Necessity of irrigation :
There is no growth of plantlife without the supply of water. India is basically an agricultural country and it's resources totally depend on the agricultural output.in order to get maximum yield, it is essential to supply the optimum quantity of water and maintain correct timings of supply. This is possible only through a systematic irrigation system.
Advantages and disadvantages of irrigation :
Advantages :
1, increase cultivation of cash crop's like sugar-cane, coffee, etc.,
2, irrigation provide's employment.
3, fish cultivation through tanks.
4, increase in revenue by power generation from hydel power stations.
5, irrigation increase food production and green revolution.
6, irrigation reservoirs control flood's by detaing them.
7, rise in social-standard.
8, by the water supply growing ornamental timber and fruit growing trees.
9, irrigation canals provide water supply for towns, villages etc.,
10, provide navigation facilities.
11, projects can provide hydro-electric power.
12, irrigation facilities are available, valuable crops like sugarcane, cotton, paddy, etc., Can be grown.
13, provide employment to the people.
14, it gives good returns in the form of irrigation charges.
15, prevents famines .
Disadvantages :
1, high initial investment is required.
2, damp and humid climate is not good for human life.
3, distribution of river water on down-stream areas is decreased because of dam-construction.
4, submergence of land on up-stream side because of reservoir construction.
5, climate humid and leads to out break of malaria.
6, water logged areas lose fertility.
7, more money is required to make them fertile again.
8, seepage water from canals fills up the fields on both sides and makes it water-logged.
Types of irrigation :
Irrigation may be classified into two types.
a, flow irrigation
b, lift irrigation
a, flow irrigation :
Water is supplied from higher level to lower level by the action of gravity is called flow irrigation.
Flow irrigation is of two types.
1, perennial irrigation.
2, inundation or flood irrigation.
1, perennial irrigation:
* Continuous water supply is ensured to the crops as per crop requirements throughout the crop period.
* Water is supplied through storage canal head-work and canal distribution system.
* Water is directed into the canal by the constructing a weir or a barrage across the river it is called 'direct irrigation'.
* Dam is constructed across a river to store water during mansoons so as to supply water into the off take canals during periods of low flow it is termed as storage irrigation.
2, inundation or flood irrigation:
* Soil is thoroughly kept submerged and flooded with water so as to cause complete saturation of the land.
* Moisture absorbed by the soil.
b, lift irrigation :
1, water is lifted by a pumps means supplie of water from lower level to higher level is called Lift irrigation.
2, under ground water is available at very low level and cannot be supplied by gravity.
3, irrigation from Wells is a good example of lift irrigation.
4, lift irrigation is of two types :
a, open well irrigation.
b, tube well irrigation.
5, open well irrigation : diameter of well range from 12 to 16 m and the water lifting devices are erected on the surface of the ground.
6, tube well irrigation : diameter of the well ranges from 0.18 to 0.27 m submergible pumps are kept below the ground level.
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