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Title: RESPONSE TO THE ASCE TASK COMMITTEE TEST CASES TO OPEN-LOOP CONTROL MEASURES

Author
item BAUTISTA, EDUARDO - CONSULTANT
item Clemmens, Albert

Submitted to: Journal of Irrigation and Drainage Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/23/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Inadequate control of water flow in irrigation canal systems can result in inaccurate, unequitable, and unreliable water deliveries to users. Improving the control of water flow in open channels is, however, a challenging technical problem. Several procedures have been proposed over the last 30 years for improving the operation of such systems. Many of these procedures have been difficult to implement in the field because the require computerized control. Although recent advances in computer technology may facilitate the application of some of these canal control procedures, there are still practical constraints that may hinder their effectiveness. In this study, we examine the performance of an existing procedure that schedules the operation of canal gates for a predetermined schedule of water demands. Simulation tests were conducted to determine how the effectiveness of the control degrades when constraints are imposed on the magnitude and frequency of gate changes. Also studied was the impact of inaccurate information about canal conditions. Results show that the effect of imposing constraints on the gate movements is very small in comparison with the effect of inaccurate information. This means that modern computerized canal scheduling methods can be effective but only if used in combination with control techniques that use actual measurements of water levels to compensate for inaccuracies of the design data.

Technical Abstract: Automated open- and closed-loop control systems can enhance the performance of irrigation delivery systems. This paper examines the response of the canal test cases developed by the ASCE Task Committee on Canal Automation Algorithms to a particular anticipatory open-loop control technique, gate-stoking. The performance of the ideal gate-stroking solution is compared to the performance of an approximate gate-stroking schedule that was generated by imposing practical constraints on the frequency and magnitude of the gate adjustments. Also analyzed were the performance of a nonanticipatory open-loop control scheme and the effect of model parameter uncertainties on the effectiveness of the control. For the test cases, the approximate gate-stroking schedules performed similarly to the ideal schedules. For two of the test cases, delivery performance was similar with and without anticipation but was substantially different for the other two tests. For all cases, the quality of the control degraded severely as a result of errors in model parameters. Results point out the importance of combining open- and closed-loop control measures to improve the overall effectiveness of the control.