ABSTRACT
A physical model of a low-head ogee spillway located on the Kissimmee River in Florida was used to determine the location and extent of maximum clear-water scour depth downstream of the structure under flow conditions of: (a) Uncontrolled Submerged flow (US); (b) Uncontrolled Free flow (UF); (c) Controlled Submerged flow (CS); and (d) Uncontrolled Jet flow (UJ). Two different lengths of riprap aprons were tested to determine their effectiveness at minimizing the scour downstream of the hydraulic structure. The study showed that doubling the length of the riprap apron had no effect on the depth of the scour for the UJ case, but it did decrease maximum clear-water scour depths significantly for the UF case and for both submerged flow conditions (CS and US). As additional protection afforded by longer riprap aprons, the maximum scour depth moved further downstream from the structure for both submerged flow and free flow cases.
