A CASE STUDY ON PROTECTIVE IRRIGATION IN A CANAL COMMAND, AREA

Abstract

Protective irrigation means irrigation with limited quantity of water spread thinly over as large area as possible so as to protect crop from total failure. The issue of protective irrigation in the Command of Right main distributary of Deoband Branch Canal (U.G.C. System,. U.P.) has been analysed using ground water balance study. For water balance study a lumped ground water balance model has been developed to assess the ground water potential for conjunctive use of available surface water and ground water. The study area covers an area of 5890 ha. Surface irrigation supplies to the area are provided through right main distributary and its branches. Right main distributary takes off from Deoband branch canal at a chainage of 7.26 km. Ground water is also utilized substantially for irrigation purpose through a large numbers of private tube well, state tubewells and pump sets. Crop water requirement has been worked out on the basis of existing cropping pattern in the command of right main distributary. The deficit between available surface water and crop water requirement has been calculated. The present surface water only irrigates 70 percent of command area. The remaining 30 percent is being supplemented by ground water. Ground water balance study indicates that there is an annual rise of 24 cm in ground water level for the existing cropping intensity 144% and normal rainfall. For 170% cropping intensity and normal rainfall the annual rise will be 6.3 cm. Thus more area can be irrigated without causing mining of ground water. There is an excess canal supply during monsoon period (July to September). If the excess supply in the above month is not given, there is annual fall of ground water level by 4.5 cm. In the case of drought period, and existing cropping intensity of 144%, water level falls by 49.5 cm. Thus the ground water can protect the crop during drought period without causing excessive mining.