Kissimmee River Structures, Central and Southern Florida Flood Control Project: Hydraulic Model Investigation

Abstract : Kissimmee River structures S-65E, S-65D, and S-65B were reproduced in a 1:20-scale model in order to study ways of eliminating scour of the downstream riprap blankets by means of structural modifications of operating procedures. All of the models had low ogee type spillways with vertical lift gates. The models and testing conditions were reproduced according to prototype data received from the U. S. Army Engineer District, Jacksonville, and the South Florida Water Management District. The only structure that has baffle blocks in the stilling basin is S-65E, and it has experienced a negligible amount of scour. Results show that little or no scour damage should have occurred downstream from the structure under normal operating conditions. Structures S-65D and S-65B experienced heavy scour of the downstream riprap blankets during a high discharge period in 1969. Two methods were evaluated to reduce the scouring action: placing baffle blocks in the stilling basin and replacing the existing 18-inch riprap with larger sizes of stone. Economic analysis by the U. S. Army Engineer District, Jacksonville, showed that it would be more economical to add baffle blocks to the stilling basins than increase the size of the riprap. Thus, only structure S-65D was tested with larger sizes of riprap. The test results showed that the scour potential will be greatly reduced by adding two rows of baffle blocks to the stilling basins. (Author)