Contents preface (VII) introduction 1—37

4.2. WELL IRRIGATION
In view of the large amount of utilisable ground water, higher agricultural yield of tubewell-irrigated lands in comparison to that of canal-irrigated lands (see Table 1.3), and favourable impact of its use on waterlogging, it is only logical to develop ground water resources for irrigation and other activities. Most of the existing canal systems in India are of a protective nature, i.e., they provide protection against famine. They were not designed to promote intensive farming. Well irrigation ensures more reliable irrigation and, therefore, enables the farmers to grow more remunerative crops with improved yield. The following are the main requirements for the success of well irrigation:
(i) Presence of a suitable aquifer which can yield good quality water in sufficient quan-tity.
(ii) Availability of energy, preferably electric power, for pumps. (iii) Well distributed demand for irrigation throughout the year.

(iv) Suitable configuration of command area with the highest ground around the centre of the command area.

GROUND WATER AND WELLS

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In general, well irrigation is more efficient than canal irrigation. The following are the comparative features of the two types of irrigation:

(i) In the canal irrigation system, major structures, such as headworks, main and branch canals, etc. must be constructed prior to the start of proportionate agricultural activ-ity which grows gradually because of the availability of irrigation facility. But, wells can be constructed gradually to keep pace with the development of the agricultural activities of the area.
(ii) Transit losses in well irrigation are much less than those in canal irrigation system. (iii) Isolated patches of high lands can be better served by well irrigation.

(iv) Well irrigation offers an effective anti-waterlogging measure of the affected lands and reduces the chances of waterlogging of canal-irrigated lands.

(v) Well irrigation ensures relatively more reliable supply of water at the time of need. This results in better yield. Besides, farmers can switch over to more remunerative crops due to the availability of assured supply.
(vi) Well irrigation needs energy for pumping. Installation and maintenance of pumps and the cost of running the pumps make well irrigation costlier.
(vii) Failure of power supply at the time of keenest demand may adversely affect the yield in case of well irrigation systems.
It is thus obvious that both irrigation systems have advantages as well as disadvantages. Therefore, both must be used in a judicious manner to obtain maximum benefits, such that there is no waterlogging and the ground water resource can be maintained indefinitely.