17.5. TERMINAL STRUCTURES FOR SPILLWAYS Some kind of energy dissipation is usually required before the spillway discharge is returned to the downstream river channel. An energy dissipator at the toe of the spillway is necessary to avoid or minimise erosion of river bed on the downstream side of the dam. A hydraulic jump is one of the best means to dissipate the excess energy of the falling water. Hence, wherever the tail-water conditions are suitable for the formation of a hydraulic jump, it is usual to provide hydraulic jump-type stilling basins which have been comprehensively studied by USBR
(9). Alternatively, bucket type energy dissipators are provided.
