21-06-2013, 04:34 PM
SYSTEMS OF IRRIGATION
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Defined Irrigation:
The process of artificial application of water to the soil for the growth of agricultural crop is termed as Irrigation otherwise it is practically a science of planning and designing a water supply system for the agricultural land to protect the crops from bad effect of drought of law rainfall.
Necessity of Irrigation:
Water is required for root zone of the plants for their growth.
(a) Insufficient rainfall:
When the seasonal rainfall is less than the minimum requirement for the satisfactory growth of crops, the irrigation system is essential.
(b) Uneven distribution of rainfall:
When the rainfall is not evenly distributed during the crop period or throughout the culturable area, the Irrigation is extremely necessary.
BENEFITS OF IRRIGATION.
a. Yield of Crops.
b. Protection from famine.
c. Improvement of Cash Crops.
d. Prosperity of revenue.
e. Source of revenue.
f. Navigation.
g. Hydroelectric Power Generation.
h. Water Supply
i. General Communication
j. Development of Fishery
Advantages of Lift Irrigation:
The farmers can supply water to their fields according to the requirement and hence there is no possibility of over irrigation.
Initial cost is low as there is no necessity of constructing hydraulic structures.
As water is supplied directly to the fields, there is no water loss due to conveyance.
The maintenance cost is low.
More than one crop can be grown in a year on the same land.
Disadvantages of Lift Irrigation:
In summer the surface water may be dried up and the water label may go down below the suction head Hence the lift Irrigation from the surface and from the shallow tube well may fail in summer.
The Well water has no silt content. The yield of Crop therefore depends on chemical fertilizer, which is costly.
The lift irrigation in consideration with the yield of crop is not cost effective.
Perennial System of Irrigation
In this system a weir or a barrage is constructed across the perennial river(i.e the river which flows throughout the year in its full capacity)to raise the water level on the up stream side or a dam is constructed to form a storage reservoir.