Alternative Delivery Scheduling for Improved Canal System Performance

Alternative delivery scheduling approaches intended to overcome the problem of low efficiency in Indian irrigation projects are presented. The features of the historical delivery schedules in the Right Bank Main Canal system of Kangsabati irrigation project, located in the state of West Bengal, India, have been studied, and nine modified schedules of varied rate rotation (variable discharge, constant duration, and constant frequency) prepared. Daily water balance simulation of the command area in the Kharif (rainy) season has been used to compare the performance of alternate schedules. An alternate schedule with three irrigations of 20 to 21 days’ duration, followed by 20 days of canal closure after each irrigation, was found to perform the best. The proposed alternate schedule results in a better match between supply and demand and results in 13% water saving when compared to the existing schedules. The irrigation periods of this schedule cover the expected dry spells and critical rice growth stage. An added advantage of the proposed schedule is an improvement in the reliability of supply, which will encourage farmers to invest more on other inputs resulting in enhanced water use efficiency and improved yields.