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Irrigation Efficiency should be around 80-90 % few percent are neglected as losses.
Irrigation may be defined as the science of the artificial application of water to the land following the crop water requirements throughout the crop period for the full-fledge nourishment of the crops.
1. Necessity of Irrigation
Rainfall differs broadly in place, time, and amount. The intensity of rainfall is very high during the period of the monsoon season and less during the summer seasons.
So crops can not be increased actually over the whole land without supplying artificial irrigation of fields.
The necessity of irrigation is as follows:
a. Non-uniform rainfall throughout the year.
b. Less rainfall than the requirement
c. Increasing food demand
d. Controlled water supply
2. Irrigation Efficiency
Irrigation Efficiency may be defined as the ratio of the water delivered to the water received and is usually expressed in terms of percentage.
The water deliver subtracted from water received to the irrigation field is nothing but losses, and hence, if losses are high, the water received is less, and therefore efficiency is less.
Hence, Irrigation efficiency is indirectly proportional to the losses. Water is lost in irrigation during different processes and therefore, there are various kinds of irrigation efficiencies, as given below:
a. Efficiency of water conveyance
The efficiency of water conveyance is the ratio of the water delivered into the irrigation fields to the water supplied or diverted from the reservoir. It takes the conveyance or transit losses into consideration.
b. Efficiency of water- application
It is the ratio of the amount of water gathered in the root zone of the crops at the time of irrigation to the amount of water delivered to the farm. It may also be called on-farm efficiency, as it takes into consideration the water lost on the farm.
c. Efficiency of water-storage
It is the ratio of the water stored in the root zone during irrigation to the water needed in the root zone prior to irrigation (i.e. field capacity – existing moisture content).
d. Efficiency of water use
It is the ratio of the water beneficially used, including leaching water, to the quantity of water delivered.
e. Uniformity coefficient or Water distribution efficiency
The effectiveness of irrigation may also be measured by its water distribution efficiency. The water distribution efficiency represents the extent to which the water has penetrated to a uniform depth, throughout the field.
When the water has penetrated uniformly throughout the field, the deviation from the mean depth is zero and the water distribution efficiency is 1.0.
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