Irrigation Water Utilisation
Agriculture is the most fundamental form of human activity. The word ‘agriculture’ has its roots in Latin word ‘agri’ meaning soil and ‘culture’ meaning cultivation. It is said that agriculture sustains the society while irrigation sustains agriculture.
The gross irrigated area in India was only 22.6 M-ha in 1950-51. The net irrigated area was 20.9 M ha, comprising of 9.71 M ha (8.3 M ha net) by major and medium projects, 6.4 M ha by minor surface water schemes and 6.5 M ha by groundwater. Since the food production was much less than the requirement, sincere efforts were made by the Govt. of India for expansion of irrigation through surface and ground water projects. An ambitious target for large-scale water resources development was set and efforts initiated to achieve it through five-year plans.
In India, irrigation projects are classified as major (having culturable command area or CCA more than 10,000 ha), medium (CCA between 2,000 ha to 10,000 ha), and minor (CCA below 2,000 ha). The source of water in major and medium schemes is surface water while the dominant source in minor schemes is ground water. The ultimate total irrigation potential from major, medium, and minor irrigation schemes has been estimated as 140 M-ha. Out of this, 76 M-ha would come from surface water and 64 M-ha from ground water sources. The ultimate potential from major and medium projects is about 59 M-ha and it is 81 M-ha from minor projects.
In India, progress of irrigation development is reported through three sets of figures: irrigation potential created; potential utilized; and irrigation by source (surface or ground water). The potential created by the year 1997 was about 91 M-ha comprising of 45 M-ha by surface water and 46 M-ha by ground water sources. Thus about 65% of the potential had been developed by 1997. The actual utilization was about 81 M-ha; the share of major and medium projects was 28 M-ha and 53 M-ha was the contribution of minor projects. Source-wise utilization was 39 M-ha from surface and 42 M-ha from ground water.
At the time of independence, canals provided irrigation to large commands over the country. Major systems included Sirhind canal (providing irrigation to 0.6 M ha), Upper Bari Doab canal (0.33 M ha), Sone canal (1.35 M ha), Yamuna canals (0.68 M ha), and Upper Ganga canal (0.7 M ha). According to Vaidyanathan (1999), total irrigation from diversion based systems was about 80% of the irrigation from major and medium projects. Proponents of diversion schemes argue that adverse social and environment impacts of these structures are much less than those of big dam projects. But it may be noted that as far as command area is concerned, both have the same impact and storages are often needed to improve reliability of diversion schemes.
Cumulative Irrigation Potential Created and Utilized for Each Five-Year Plan
Statewise Irrigation Potential, Potential Created and Gap from Surface Water and Ground Water(all in 1,000 ha)
Percentage of Net Irrigated Area to Total by Wells and Tube-wells
(Source : www.ncert.nic.in)
Although irrigation is the major water user, due to more pressing and competing demands from other sectors, its share in the total demand is bound to decrease from the present 83%. It is also expected that the price of water for agriculture will rise in future so as to recover a part of expenditure in operation and maintenance of irrigation works and this will result in higher water use efficiency. Estimates show that a 10% increase in the efficiency in irrigation will yield enough water to irrigate an additional 14 M-ha land. This much improvement in efficiency will require very moderate investment and user education. Consequently, the share of agriculture in total water demand by the year 2025 is expected to be about 75 percent.
Water Requirement for Irrigation