HYDRAULICS OF EMBANKMENT WEIRS

Embankment weirs, often found in engineering applications with a side slope 1V:2H, are considered in this paper. For free overflow, the disc harge coefficient is determined in terms of relative crest length for long broad-crested, broad-crested, short-crested, and thin-crested wei rs. A considerable increase of capacity is noted when compared to broa d-crested weirs with vertical faces. For submerged overflow, four regi mes are identified: (1) A-jump; (2) plunging jet; (3) surface wave; an d (4) surface jet. Particular attention is focused on plunging jets an d surface waves. The flow regimes are discussed in terms of submergenc e, crest length, and modular limit. A description is given of the forw ard and backward (recirculation) zones with indications of typical len gths. Also, the entire velocity field is described, including the maxi mum forward and backward velocities, and the velocity distribution in arbitrary sections of the tailwater region. It is found that plunging jets and surface jets are hydraulically similar, and that the profile of one regime can be transformed into the other profile by inversion a bout the median. All results are generalized and can be directly appli ed.