Irrigation

The process of supplying water to crops by artificial means such as canals, wells, tube-wells, tanks, etc. from the sources of water such as rivers, tanks, ponds or underground water is called irrigation.

Means of Irrigation

Wells, including tube wells, canals and tanks are three main sources of irrigation in India. Their relative significance varies in different parts of the country depending upon the geographical conditions.

(i) Wells

A well is hole dug in the ground to obtain the subsoil water. An ordinary well is about 3-5 metres deep but deeper wells upto 15 metres are also dug. This method of irrigation has been used in India from time immemorial. Well irrigation is popular in areas where sufficient sweet groundwater is available. These areas include a large part of the Great Plain, the deltaic regions of the Mahanadi, the Godavari, the Krishna and the Cauvery, parts of the Narmada and the Tapi valleys and the weathered layers of the Deccan Trap and crystalline rocks and the sedimentary zones of the Peninsula. However, the greater part of the Peninsular India is not suitable for well irrigation due to rocky structure, uneven surface and lack of undergound water. Large dry tracts of Rajasthan, the adjoining parts of Punjab, Haryana, and Gujarat and some parts of Uttar Pradesh have brackish groundwater which is not t for irrigation and human consumption. However, some parts of these states have sufficient amount of sweet ground-water and are t for well irrigation. At present nearly two-thirds of the total irrigation area of India is irrigated by wells and tube wells.

The largest concentration of well irrigation is in three states of Uttar Pradesh, Rajasthan and Madhya Pradesh. These three states account for more than half of well irrigation in India. These are comparatively drier areas which do not receive sufficient rainfall. As such there is shortage of surface water and these areas have to depend upon the availability of groundwater. Consequently, well irrigation forms an important sector of farming activity in these areas. Punjab, Gujarat, Maharashtra, Bihar, Andhra Pradesh, Haryana, Tamil Nadu and, Karnataka are the other states where well irrigation is used to supply water to the crops. However, well irrigation is prevalent only in those areas where ground is available, ground water level is not very deep and soil is soto facilitate digging of wells.

(ii) Tank Irrigation

A tank consists of water storage which has been developed by constructing a small bund of earth or stones built across a stream. Tanks are of varying size but most of the tanks are of small size and are built by individual farmers or groups of farmers. There are about 5 lakh big and 50 lakh small tanks irrigating over 20 lakh hectares of agricultural land. e ratio of tank irrigated land to the total irrigated area of the country has reduced from 14 per cent in the 1960-61 to about 3.5 per cent in 2010-11, primarily due to increase in canal and well irrigation and partly due to fall in the tank irrigation.

Tank irrigation is popular in the peninsular plateau area of India where Andhra Pradesh Telangana and Tamil Nadu are the leading states. Andhra Pradesh and Telangana have the largest area of 662 thousand hectares which is about one-third of the total area under tank irrigation in the country. Most parts of these two states, except the Godavari-Krishna delta, receive irrigation from tanks. About 575 thousand hectares are irrigated by tanks in Tamil Nadu. s amounts to about 28 per cent of the total tank irrigated area of India. Tank irrigation accounts for over 21 per cent of the total irrigated area of Tamil Nadu. The other states where tanks constitute an important source of irrigation are Uttar Pradesh, Karnataka, Madhya Pradesh, Bihar and Rajasthan.

(iii) Canals

Canals used to be the most important source of irrigation upto 1960s, but in the 1970s they yielded first place to wells and tube wells and now constitute the second most important source of irrigation in India. The percent age of canal irrigation area to total irrigated area in the country has fallen from about 39.77 per cent in 1950-51 to 26.31 per cent in 2010-11.

Canals can be an effective source of irrigation in areas of low level relief, deep fertile soils, perrenial source of water and extensive command area. Therefore, the main concentration of canal irrigation is in the northern plain of India, especially the areas comprising Punjab, Haryana and Uttar Pradesh. The digging of canals in rocky and uneven areas is difficult and uneconomic. Thus the canals are practically absent from the Peninsular plateau areas. However, the coastal and the delta regions in South India do have some canals for irrigation.

Important Irrigation Canals in India:

Uttar Pradesh: Upper Ganga Canal, Lower Ganga Canal, Sharda Canal, Eastern Yamuna Canal, Agra Canal and Betwa Canal

Punjab: Upper Bari Canal, Sirhind Canal, Bhakra Canal, Bist Doabe Canal

Haryana: Western Yamuna Canal, Bhakra Canal, Jui Canal, Gurgoan Canal

Bihar: Eastern Sone Canal, Western Sone Canal, Eastern Kosi Canal, Western Kosi Canal, Eastern Gandhak or Tishu Canal, Western Gandak or Saran Canal, Triveni Canal

Rajasthan: Indira Gandhi Canal, Chambal Project, e Gang or Bikaner Canal, Jawai Project, Parbati Project, Gudha Project, Ghaggar Canal, Pichura Canal, Banas Canal, Bharatpur Canal

Madhya Pradesh: Chambal Project, Mahanadi Canal, Wainganga Canal, Tandula Canal, Tawa Project, Barna Project

Multipurpose Projects

Multipurpose projects aim at water storage, flood control, irrigation, hydroelectric generation, checking soil erosion, development of inland navigation reclamation of waterlogged areas, development of fisheries and tourism etc.