Calibration equations for free-flowing radial gates typically provide sufficient accuracy for irrigation district operations. However, many water purveyors have difficulty in determining accurate discharges when the downstream water level begins to submerge the gate. Based on experimental laboratory studies, we have developed a new calibration method for free-flowing and submerged radial gates that allows for multiple gates and widely varying upstream and downstream channel conditions. The method uses the energy equation on the upstream side of the structure and the momentum equation on the downstream side, and thus is called the Energy-Momentum Method. An iterative solution is required to solve these two equations, but this allows calibration from free flow to submerged flow continuously through the transition. Adjustments to the energy equation for free flow are described, along with an additional energy adjustment for the transition to submerged flow. An application is used to describe the new procedure and how it overcomes the limitations of current energy-based methods.

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I. Hypothesis, Experimental Procedures, and Cropping ResultsAn irrigation/cropping management strategy has been developed to facilitate the use of brackish waters for irrigation, with the goal of expanding the available water supply and minimizing the otT-site pollution potential of drainage disposal. A field experiment conducted in the Imperial Valley of California to test the strategy has produced four years of cropping results. After seedling establishment, when the crops were in a sufficiently mature, salt-tolerant growth stage, brackish drainage water (Alamo River) was substituted for the normal water (Colorado River) to irrigate wheat and sugarbeets (in a succes- Continued inside back cover

Long-throated flumes and broad-crested weirs have become accepted standards for open-channel flow measurement during the past two decades. These structures offer the accuracy and reliability of critical-depth flow measurement, theoretically based calibrations, the lowest head loss requirement of any critical flow device, and extraordinary design and construction flexibility. Computer software developed in recent years has streamlined the design and calibration process. The software, WinFlume, has been described in several papers and a recent text. Although WinFlume is very easy to use, there is still a need for simplified design and calibration tools for situations where use of the computer model is not possible or desirable. This paper combines several previous efforts to provide such tools in both metric and English units for the most typical measurement applications encountered in irrigation and drainage systems. Pre-computed designs for trapezoidal broad-crested weirs, long-throated flumes with rectangular control sections, broad-crested weirs in circular pipes, V-shaped long-throated flumes, and portable RBC flumes are presented in easy-to-use tables that provide head and discharge ranges, Au cours des vingt dernières années, des canaux jaugeurs à col allongé et des déversoirs à crête épaisse sont devenus les normes acceptées pour les mesures de débit à surface libre. Ces structures possèdent l'exactitude et la fiabilité des mesures des débits de profondeur critique, des étalonnages théoriques, la caractéristique de perte de charge la plus basse de n'importe quel dispositif d'écoulement critique et une extraordinaire souplesse de conception et de fabrication. Un logiciel développé ces dernières années a simplifié les modalités de conception et d'étalonnage. Le logiciel, WinFlume, a été décrit dans plusieurs articles et dans un texte récent. Bien que WinFlume soit d'un emploi très facile, on a toujours besoin de conception et d'outils d'étalonnage simplifiés dans les cas où la modélisation par ordinateur n'est pas possible ou pas souhaitable. Cet article associe plusieurs efforts effectués auparavant pour fournir de tels outils utilisant des unités métriques et anglaises pour les programmes de mesures les plus courants rencontrés dans les systèmes de drainage et d'irrigation. Des conceptions précalculées pour des déversoirs à trapézoïdaux à crête épaisse, des canaux jaugeurs à col allongé à sections de contrôle rectangulaires, des déversoirs à crête épaisse dans des tuyaux circulaires, des canaux jaugeurs à col allongé en V et des canaux jaugeurs portables RBC sont présentés dans des tableaux faciles d'emploi qui indiquent les gammes de

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