Mathematical Semi-analytical Model of Combined Flow over Weir and under Gate by Different Geometries

The most important advantage of applying the combined weir and gate is to maximize its performanceunder sedimentation conditions. In this paper, a new mathematical model is presented to determine therelationship between stage and discharge for structures consisting of the weirs and gates by differentgeometries in different flow conditions. Since the geometry of these structures has lateralcompression, velocity distribution in transverse section is not uniform. Therefore, the energy andmomentum correction coefficients should be used, and in this research, these coefficients arecalculated using optimization approach. One great important advantage of this procedure is the use ofrelatively simple hydraulic principles. To verify the given method, different combinations of weir andgate as a physical model are tested in the laboratory. From the laboratory data it is concluded that theproposed method is capable of calculating stage-discharge relationship by reasonable accuracy.