Reducing the Impacts of Withdrawals on the Water Distribution in Main Irrigation Canals Based on a Modified Smith Predictor Control Scheme

The main function of irrigation canals is to transport water efficiently from a source to target locations, but flow disturbances caused by farmer withdrawals often reduce water delivery efficiency to the destination. The dynamics of these canals involve a significant time delay. To address this, control systems based on the Smith predictor suitable for time-delayed systems have been proposed. However, the classical Smith predictor struggles with disturbance rejection, prompting recent modifications to enhance this capability. This paper addresses a new robust Smith predictor control scheme that outperforms previous modifications. Our study utilized a laboratory irrigation canal platform to identify its dynamics, including those caused by flow disturbances. The proposed control system was then designed and evaluated for disturbance rejection and robustness. Simulations comparing the scheme with other methods highlight its superiority, which was further validated through practical experiments, demonstrating the improved rejection of flow disturbance effects over the standard Smith predictor.