Sectoral Conjunctive Use Planning for Optimal Cropping under Hydrological Uncertainty

Abstract

The canal command of the Hirakud multipurpose major irrigation project of Orissa in eastern India is under severe threat of waterlogging in the monsoon season and acute shortage of irrigation water in the nonmonsoon season. An irrigation scheduling model (ISM) and a linear-programming optimization model (LPM) under hydrologic uncertainty were developed with a view to manage the available land and water resources of the canal command effectively. The ISM was used to predict actual crop yield under different irrigation strategies—namely, full and deficit depths of irrigation. The crop yield obtained by the ISM under different irrigation management strategies was used in the LPM to optimize the land and water resources of the canal command at different probability of exceedances of net irrigation requirement and canal-water availability. The net annual return was found to decrease with the increase in the level of deficit with maximum return under full irrigation strategy. Hence, from the benefit point of view, crops must be provided with adequate irrigation. Most beneficial crops with comparatively lower water requirements, like pulses and vegetables, should be given priority, and the present practice of extensive rice cultivation should be limited to minimum possible extent for sustainable protection against global warming. It was also found that the uncertainty factor does not show any visible effect on the cropping pattern, which in turn is reflected in the overall water resources utilization pattern of the canal command. From the sensitivity point of view, cropping area should be given emphasis, followed by the market price and cost of cultivation of different crops during the course of further study.