Observations on dam overtopping protection: RCC stepped spillway research

Research conducted over the last decade has led to improved understanding on the design and hydraulic performance of stepped spillways applied to embankment dams for overtopping protection. This research has demonstrated that the free-surface inception point (Li), step height to critical flow depth ratio (h/dc), chute slope (θ), clear water flow depth (ycw), and mean air concentration (Cmean) are vital parameters in the design of stepped chutes applied to embankment dams as well as the associated stilling basin for these structures. Relationships based on data obtained from this research have led to improved design criteria for these structures and addressed knowledge gaps on their performance. Correct and proper interpretation of the data are vital to limit the introduction of model scale effects into the results. © 2018 Association of State Dam Safety Officials.