Computerized scheduling for irrigation management and pumping operations in the watercourse command

Abstract

A model to simulate the irrigation schedules of a watercourse command was developed to predict cropping intensity, net farm return, farm water use, percent water utilized, deep percolation at farm level, rainfall contribution, and extra tubewell water pumped. Schedules for three selected farms on a watercourse command in Sargodha, Pakistan were simulated with three fixed-rotation strategies and compared to a demand strategy. The fixed-rotation strategies were also compared for evaluation of the allowable depletion criteria. Evaluation of simulations (1973–1982) showed that the three fixed-rotation strategies reduced the net farm return by 28–43% from that of a demand strategy. The fixed-rotation system also had 17–39% of extra water pumped from a public tubewell. Therefore, when the existing operation schedules of the tubewells are matched with the actual crop water needs an ultimate saving of 17–39% in water pumpage and energy consumed will be reached in a fixed-rotation system. The change of the fixed-rotation system to a demand system will significantly increase the net farm return in addition to improved water allocation to various farms on a watercourse command. The demand strategy will provide saving in energy due to scheduled pumping operations and effective utilization of canal water supplies.