|Van overloop, P.-j.|
Submitted to: Journal of Irrigation and Drainage Engineering
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/10/2011
Publication Date: 5/12/2011
Citation: Clemmens, A.J., Litrico, X., Van Overloop, P., Strand, R.J. 2011. Estimating canal pool resonance with auto tune variation. Journal of Irrigation and Drainage Engineering. doi:10.1061/(ASCE)IR.1943-4774.0000384. Interpretive Summary: Water supplies in arid parts of the U.S. are limited and methods are being developed to improve water utilization. Automatic control of irrigation canals is one method for improving control of water supplies. Design of canal controllers requires knowledge of canal water level response to control actions (for example gate movements). Previous research had demonstrated that the Auto Tune Variation method could be use to determine some canal pool properties. However, additional information is required for canal pools in which gate movements create oscillations, reflection waves that travel up and down the canal. In this paper, we show that the magnitude and frequency of these oscillations can also be determined from the Auto Tune Variation method. These results will be of use to irrigation and large water districts, the Bureau of Reclamation, and consultants.
Technical Abstract: The Integrator-Delay (ID) model is commonly used to model canal pools which do not exhibit resonance behavior. Simple step tests are often used to estimate ID model parameters; namely, delay time and backwater surface area. These step tests change the canal inflow at the upstream end of the pool and observe water depth variations at the downstream end. Some knowledge of the canal pool characteristics are needed to determine the amount of flow change and its duration. The Auto Tune Variation (ATV) method is one method for determining the duration of these step tests, as well as the delay time and backwater surface area. Pools that are under backwater over their entire length tend to exhibit oscillations due to resonance waves. Binary-Random-Sequence (BRS) tests have been used to determine the resonance frequency of such pools, where step tests with different durations are used. PBRS tests are difficult to implement in practice and may not provide the resonance frequency. The intent of this paper is to demonstrate on a real canal that the ATV method can determine both the resonance frequency and the resonance peak height for canal pools that are under backwater.