David Lozano

Field calibration of submerged sluice gates in irrigation canals.

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 (E-M) equations proved to be sound. The calibration of the contraction coefficient, to be used in the energy equation, allowed good estimations of the discharge for three of the four gates studied. The gate for which the E-M method did not perform satisfactorily was located at the head of the canal with a unique nonsymmetric approach flow condition. Alternatively, we investigated the performance of the conventional discharge equation. The variation of the discharge coefficient, Cd , with the head differential,...

Energy and momentum velocity coefficients for calibrating submerged sluice gates in irrigation canals.

There is renewed interest in developing calibration methods for gates operating in submerged conditions in irrigation canals. In the present study, a new method based on a generalization of the standard energy-momentum method that accounts for variations in the energy and momentum velocity coefficients is proposed, for the following reasons. First, it was found that the assumption of uniform submerged jet velocity to account for the kinetic energy head and momentum flux is in reality equivalent to assuming a parabolic relationship between the Coriolis and Boussinesq coefficients. Second, literature investigations showed that the coefficients for the downstream side of submerged gates are notably greater than unity, and the implicit parabolic relationship between these coefficients in the standard energy-momentum method is inadequate, at least for high submergence conditions. The proposed energy-momentum method was evaluated using the data obtained from four gates operating in an irrigation canal in Southe...

Simulation study on the influence of roughness on the downstream automatic control of an irrigation canal

AbstractThe controllability of an irrigation canal depends on its physical characteristics, on the control algorithm used, and on the actual condition of the canal in relation to the algorithm tuning conditions. The flow conditions and controllability in an irrigation canal may change if the hydraulic friction changes. Great variations in friction were observed in an irrigation canal in Spain owing to the presence of Rhizoclonium hieroglyphicum, a type of algae that grows in clear water. Such large variations in friction may have a significant effect on the stability and performance of automatic canal controllers. Using the unsteady-state model Simulation of Irrigation Canal (SIC), the influence of roughness on the performance of the study canal under distant downstream control of its four coupled pools was investigated. A set of proportional-integral (PI) controllers was tuned for different values of Mannings n. The controller’s performance under real conditions is sensitive to the roughness conditions ...

Evaluating the Effects of Constructing a Tail Reservoir in a Canal with Automatic Distant Downstream Control

AbstractAlthough canal control automation has been generally disregarded in the irrigation modernization projects in Spain, regulation reservoirs formed part of most projects. Recent projects combining storage reservoirs with automatic canal control lack clear design criteria, although they are influenced by the evident benefits from the construction of reservoirs at the tail of large canals with upstream control. A case study is presented herein that evaluates the effects of enlarging the downstream pool of one of the few irrigation canals that is operated automatically in Spain using distant downstream control. The study used an unsteady flow hydraulic model that proved to be a very useful tool for demonstrating to district managers the advantages and disadvantages of alternative control strategies, including the construction of a reservoir at the canal tail.