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ARS Home » Pacific West Area » Maricopa, Arizona » U.S. Arid Land Agricultural Research Center » Water Management and Conservation Research » Research » Publications at this Location » Publication #234857

Title: Field calibration of submerged sluice gates in irrigation canals

item Clemmens, Albert

Submitted to: Journal of Irrigation and Drainage Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/15/2009
Publication Date: 3/18/2009
Citation: Lozano, D., Mateos, L., Merkely, G.P., Clemmens, A.J. 2009. Field calibration of submerged sluice gates in irrigation canals. Journal of Irrigation and Drainage Engineering. 135(6):763-772.

Interpretive Summary: Agricultural water purveyors are being pressed by other water users to improve water measurement, control, and accounting, while their water users are demanding more flexible water deliveries so they can compete in the marketplace and implement water conservation measures on farm. Operation of irrigation-water delivery systems can be improved by providing canal operators with better tools for measuring flow rates. Vertical sluice gates are commonly used to control and measure flow rates within irrigation canals. Unfortunately, calibration of these gates has been problematic, particularly when the downstream water level is high (that is, the gate is submerged on the downstream side). This paper presents the results of field studies on the calibration of sluice gates for an irrigation district in Southern Spain. A variety of calibration equations are used. The new energy-momentum calibration equation provided acceptable calibrations, but did not provide better results than other, more empirical equations. These results should be of use to irrigation districts, consultants, and the U.S. Bureau of Reclamation. Ultimately better management of irrigation water supplies will conserve water and benefit the environment.

Technical Abstract: Four rectangular sluice gates were calibrated for submerged-flow conditions using nearly 16,000 field-measured data points on Canal B of the B-XII irrigation scheme in Lebrija, Spain. Water depth and gate opening values were measured using acoustic sensors at each of the gate structures, and the data were recorded on electronic data loggers. Several gate calibration equations were tested and it was found that the rectangular sluice gates can be used for accurate flow measurement. The Energy-Momentum equations proved to be sound. The calibration of the contraction coefficient, to be used in the Energy equation, allowed good estimations of the discharge under three of the four gates studied. The gate for which the Energy-Momentum method did not perform satisfactorily was located at the head of the canal with a singular placement. Alternatively, we investigated the performance of the conventional discharge equation. The variation of the discharge coefficient, Cd, with the head differential, delta h, and the vertical gate opening, w, suggests that Cd be expressed as a function of these two variables. For the sluice gates considered in this study, the best empirical fit was obtained by expressing Cd as a parabolic function of w, although an exponential expression tested previously by other authors also produced satisfactory results. The greatest uncertainty in the variables considered in this study was found to be in the calculated coefficient of discharge. And, based on the uncertainty analysis, it is possible to quantify the uncertainty in the estimated discharge through a calibrated sluice gate. The discharge uncertainty in each of the four gates in this study decreases with increasing gate opening, and it decreases slightly with increasing head differentials.