Irrigation is the Science of providing water to the lands in accordance with
the requirements of the crops grown therein. It has been found to increase the
productivity of rain-fed lands by as much as five times in a tropical country
like India. The annual fresh water supply (runoff) in India in 1869 b.cum.
However, the present utilisation (1997) is only 605 b.cum for all its uses. Out
of this, about 500 b.cum, i.e. about 83%, is being used for irrigation alone.
Even with such a huge percentage of utilisation of water for irrigation, we are
just able to