Well and Tube Well irrigation is the most popular irrigation system in India. The first tube well was dug in 1930 in Uttar Pradesh. Today there are more than 50 lakh tube wells operating in different parts of India. It has contributed substantially for the success of Green Revolution in India. Uttar Pradesh has the largest area under well irrigation. It is followed by Rajasthan, Madhya Pradesh, Punjab, Gujarat, Maharashtra and Bihar.
Types of wells
The utilization of groundwater through dug well irrigation is an indigenous form of irrigation. A dug well is a shallow well, with its bottom on a fair depth below the water table, so that water from the surrounding aquifer accumulates in the well. Water collected in the well is lifted to ground surface through a water lift. The masonry lined dug well usually yields 7 to 8 m3 per hour (@ 2 1ps) when operated with a Persian wheel, which is the case for about 20% of the masonry wells. In the remaining dug wells, the water is lifted by animal power with leather or metal buckets, usually bullocks. These wells have very limited discharge rates and this practice is almost dispensed with due to high cost of labour and drudgery.
• Shallow tube wells are drilled to penetrate a shallow aquifer and are usually less than 30 m deep. This depth is only possible when the tube well is placed at the bottom of a dug well, so that it is a dug-cum-tube well. Shallow tube wells are usually equipped with a small centrifugal pump. The filter point wells if Cauvery deltas of Tamil Nadu in Trichy, Thanjavur, Thiruvarur, Nagapatinam districts are shallow tube wells irrigating individual farms. The electric or diesel motor is directly connected to the pump by a belt drive. The centrifugal pump is placed at the surface level and operates mainly in suction mode. These wells usually have a capacity of 20 to 30 m3h-1 (@ 7 lps).
• Medium tube wells are small diameter submersible tube wells equipped with a strainer section. These wells are usually about 45 m in depth although they may be deeper depending on the depth of the aquifer and the capacity desired. They usually have capacities of about 30 to 40 m3h-1 (@ 10 1ps) and are equipped with centrifugal pumps. Water distribution from these wells is through small unlined channels with the following lengths: masonry wells - 30 m; shallow tube wells - 200 m; and medium tube wells - 400 m.
• Deep tube wells have a large diameter and vary in depth from 40 to 300 m. Pumps are sunk into the well, operate in force mode, and are driven by submersible electric engines or by shafts connected to engines at the surface. Deep tube wells have a large discharge capacity varying from 150 to 300 m3h-1 (40 to 80 lps). As discharge capacity increases, the length of the water distribution channels increases accordingly. For example a command area of 100 ha is served by water distribution system of 4 km in state tube well commands of UP, water is distributed through unlined earthen channels.
Benefits of Well and Tube Well Irrigation
• The Green Revolution expanded through it in other areas of the Country.
• The farmers became more self-dependent. The compulsion of dependence on the government system for canal irrigation got minimized.
• Decrease in expenditure for irrigation.
• Decrease in wastage of water.
• The problem of deposition of slat and sand ended which was the main problem of the canal irrigation.