Lift irrigation

Lift irrigation is a method of irrigation -in which water is not transported by natural flow (as in gravity-fed canal systems) but is lifted with pumps or other means.

Lift irrigation schemes must accomplish two main tasks: first, to carry water by means of pumps from the water source to the main delivery chamber, which is situated at the top most point in the command area. Second. they must distribute this water to the field of the beneficiary farmers by means of a suitable and proper distribution.

Of these two issues, distribution is the most complex, for several reasons. First, whereas the system for collecting water at the main delivery chamber makes use of pumps, the distribution system is typically completely gravity-based, and have to be designed solely on the basis of the available hydraulic head. In addition, the area to be irrigated is scattered and has varying topography, and each farm is of a different size, so it can be a challenge to design a gravity-based system that allots each farmer a fair amount of water. Several mechanisms have been developed to meet these challenges.

In the most prevalent system, the area under irrigation is divided into different blocks according to topography determined by contour plan. The water requirement for each block is determined, and pipe lines are designed for these blocks depending on the available head and required discharge. Field delivery chambers are then constructed on the distribution pipe lines, and valves are fitted to control the flow of the pipe lines, with flow from the main delivery chamber controlled by these valves. In this system, lines for lower fields have more discharge, because the force of gravity is greater, so water distribution can be unequal.

In other systems, the area is divided into three or four equal parts, and each part is given the entire discharge for one day. This means each part gets rotation of the full design discharge on the fourth or fifth day. Again, however, water distribution can be unequal, and alternate methods of distribution have been proposed to deal with this problem.

In LI water is lifted from lower level to higher level with the help of pumps and other equipment. Construction of dams and canals helped tremendously to increase the irrigated area lying at lower level than the dam level, but scarcity of water remained the problem for higher level areas. So as to bring higher level area under irrigation L.I.S. are taken up.The 8% of Maharashtra irrigation is occupied by lift irrigation.

In India, the National Bank for Agriculture and Rural Development reports that there are 1401 lift irrigation schemes financed by them. These schemes irrigate 22000 hectares of land, and have a total financial outlay of Rs. 6462.5 million. However, as many as 573 of these schemes are defunct, mainly due to poor distribution of water. Other schemes have been financed by the government, sugar factories, or individual farmers.

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