Submitted to: Workshop on Modernization of Irrigation Water Delivery Systems
Publication Type: Proceedings
Publication Acceptance Date: 10/21/1999
Publication Date: N/A
Interpretive Summary: Improving water flow control in large open-channel delivery systems can improve the accuracy of water deliveries to farmers and, consequently, promote better water management on-farm. Unlike pipelines, open channels respond slowly to changes in upstream inflow or to other control actions. Therefore, an alternative for improving canal control is to schedule the operation of control structures in anticipation of the known or predicted demands. This control approach is referred to as anticipatory feedforward control. Anticipatory control methods currently being used rely on empirical rules and operator experience. A mathematically sophisticated computerized anticipatory control method has been proposed in the past, but it is not being used because it cannot be easily implemented in the field. This paper describes a simple computerized anticipatory control system for open-channel flows. The proposed method overcomes the practical limitations sof the earlier more sophisticated control system. The paper also compares the performance of the two methods, and results show great potential for the newly proposed approach. Irrigation districts and engineering consultants should find this technology valuable.
Technical Abstract: A simple approach for computing an anticipatory open-loop (i.e, feedforward) control schedule to satisfy known water demand changes in open channels has been developed. The methodology assumes a succession of steady states and takes into account pool volume changes and delay times to generate a schedule of check flow rate changes. This paper describes the method and compares its performance with an alternative scheduling method, gate-stroking, for two canals with different physical characteristics and flow conditions.