Design Examples Of Stilling Basins Downstream Of Stepped Spillways

Advances of roller compacted concrete (RCC) in the construction of concrete dams has significantly influenced the development of stepped spillways. The latter are now more frequently implemented in the rocky abutments of embankment dams. The energy dissipation downstream of stepped chutes is mostly ensured by stilling basins. Such stilling basins are typi-cally designed according to guidelines developed for basins below smooth chutes. A systematic experimental research study revealed that these design guidelines are not applicable for stilling basins with stepped chute approach flows. The aim of this paper is thus to present a practical design guide-line for stilling basins downstream of stepped chutes based on two design examples that highlight the significant differences with smooth approach flows.