Energy dissipation and flow resistance on flat slope stepped spillways

A range of stepped spillway configurations typical of embankment dam were studied with slopes between 8.9 and 26.6 degrees. Detailed air-water flow data were compared with earlier results. For all configurations, the residual energy was calculated at the chute downstream end and the Darcy friction factor was estimated in the air-water flow region. The results showed that the stepped chutes could be differentiated into four different slope groups. For each group, the residual energy was similar and a simple design criterion to assess the energy dissipation performances. The design guidelines are applicable for a wide range of discharges in transition and skimming flows. Overall the stepped chute design with theta = 21.8 degrees was the most efficient in terms of rate of energy dissipation.