Abstract:
Stepped spillways are known to have a higher energy dissipation potential when
compared to a smooth invert chute of identical slope. Therefore, the length of downstream energy
dissipators can be reduced. To date, little is known about the effect of the stepped profile on the
stilling basin performance. Therefore, new measurements were carried out on a large-scale stepped
spillway model in combination with a USBR type III stilling basin, where conventional and
modified chute blocks were analysed. Pressure heads and flow depths along the basin were
measured systematically for several flow rates and tailwater conditions. The results follow the
recommendations by the USBR for type III basins except at the basin entrance, similarly as
observed in previous studies. The conventional or modified chute blocks were found to have a
minor influence on the pressure head.
