Control of an irrigation canal

A control algorithm to maintain a constant water depth at every pool of a multireach irrigation canal is presented. A simplified model of the dynamic response of the downstream water depth is obtained as a three-parameter exponential. This model, which predicts the future error signal, incorporates actual canal information and is used in the calculation of control adjustments. The effectiveness of the control algorithm is demonstrated by three examples of computer model simulation of a real irrigation canal, with variable reach characteristics. Perturbations of an equilibrium are considered, which simulate the opening or closing of an offtake. Using information about the actual water levels and gate openings in the canal, the controller restores the set-point downstream water depth. Results show the controller to be accurate, fast, and stable, despite the variable characteristics of the canal reaches involved.