Irrigation is a process of the supplying water to the dry land as a supplementation of rain water for cultivation. There are various types of systems of irrigation practices in different parts of India. Irrigation in India is carried on through wells, tanks, canals, Perennial canal, Multi-purpose river valley projects, etc. About one-third part of the net sown area of India is irrigated. According to 2008-09, the total irrigated land in India is about 631.96 lakh hectare. There is the need for development of the means of irrigation for agriculture in India because of tropical climate and indefinite, unequal and short period monsoon rain. Here, three major means of irrigation are in vogue:
• Canals (Surface water resources)
• Wells and tube wells (Underground water resources)
• Tanks (Ponds) (Surface water resources)
Several canals and ponds were built during the British period. Sarhind Canal, Eastern and Western Yamuna Canal, Detai Canal of the Kaveri and Anicut Canal were the major canals during this period. Canals were the major means of irrigation till 1950 and its share in the total irrigation area was 39.9 %. Since independence, area irrigated by canals has gradually increased (about two times) but its share in comparison to other means of irrigation has decreased. The share of irrigation by canals in total irrigated area of the country during 2008-09 had remained 26%.
There has been an increase in the areas irrigated by wells and tube wells due to the use of diesel and electric pump sets. During 2008-09 the share of irrigated areas by them was 61 % in comparison to 29.7 % in 1950.
Nearly 1/10th of the total area of our country receives an annual rainfall of over 200cm. on the other hand, almost 1/3rd of it total area receives an annual rainfall between 0 to 10cm. as a result, some parts of the country are affected by floods while others have scanty rainfall leading to drought condition. In the catchment areas of planting trees is undertaken. It is known as afforestation. It helps in conserving both water and soil. Water falling downstream from the dams is used for turning turbines. It in turn produces electricity, called hydro-electricity. This is an inexhaustible source of electricity at low-cost, which is clean and non-polluting.
The Damodar valley project in Bihar and West Bengal was the first multi-purpose river valley project in independent India. The Bhakra Nangal is another project on river Satluj. The Bhakra dam with a height of 225ms is the world’s highest gravity dam. The states of H.P., Punjab, Haryana, Rajasthan and Delhi are benefited by this project. An effort is being made to develop a national water grid linking the Himalayan and the peninsular rivers so that water can be transferred from water-surplus to water-deficit river basins.
Irrigation Planning in India by Planning Commission
• Major Irrigation Plan: Those irrigation projects are included in it which is implemented for irrigation in cultivable command areas of 10, 000 hectare or more. Often large canals and multipurpose river valley projects are included in it.
• Medium Irrigation Plan: Those irrigation projects are included in it which is implemented for irrigation in cultivable command areas of 2000 hectare or more but less than 10, 000 hectare.
• Minor Irrigation Plan: Those irrigation projects are included in it which is implemented for irrigation in cultivable command areas of less than 2000 hectare.