Irrigation scheduling and water availability at watercourse command

Abstract

A model that simulated the irrigation schedules of a farm at watercourse command was developed to predict net farm return, benefit-cost ratio, water use, percent water utilized, deep percolation, rainfall contribution and net return per unit of water applied including rainfall. Schedules for three selected farms on a watercourse command of Tw #62394L from MONA, Sargodha, Pakistan were simulated with 3 fixed-rotation and 2 demand strategies to evaluate the allowable soil water depletion criteria. Evaluation of the simulations (1973–82) showed that the water availability reduced the net farm return of 15 and 31% at the middle and tail farms, respectively, from that of the head farm. Therefore, the existing water allocation procedure (WARABANDI) should include watercourse conveyance losses to provide equitable water distribution on a watercourse command. Demand water availability can increase the net farm return of 25 and 26% in strategies 4 and 5, respectively, by changing the fixed-rotation system to a demand system. Changing the fixed-rotation system to a demand system requires either the use of existing private tubewells or the installation of new private tubewells.