A spillway system is an aperture designed to spill safely the flood waters and dissipate the turbulent kinetic energy of the flow before it rejoins the natural river channel. The construction of steps on the spillway may assist with the energy dissipation, thus reducing the size of the downstream stilling structure. The construction of stepped spillways is compatible with the placement methods of roller compacted concrete and gabions. The main characteristics of stepped spillway flows are the different flow regimes depending upon the relative discharge, the high turbulence levels and the intense flow aeration. Modern stepped spillways are characterised by a relatively steep slope and large flow rates per unit width. The chute toe velocity may be estimated using a graphical method, and the downstream energy dissipator must be designed accurately with the knowledge of the air-water flow properties. As the flow patterns of stepped spillways differ from those on smooth chutes, designers must analyse carefully stepped chute flows and their design is far from trivial.
Stepped spillway research at the University of Queensland has been very active for the past 25 years. Combining field observations with physical experiments, new theoretical models were developed. The video summarises the current state-of-the-art.
CHANSON, H. (2001). "The Hydraulics of Stepped Chutes and Spillways." Balkema, Lisse, The Netherlands (ISBN 90 5809 352 2).
CHANSON, H., BUNG, D., and MATOS, J. (2015). "Stepped spillways and cascades." in "Energy Dissipation in Hydraulic Structures." IAHR Monograph, CRC Press, Taylor & Francis Group, Leiden, The Netherlands, H. CHANSON Editor, pp. 45-64 (ISBN 978-1-138-02755-8).
ZHANG, G., and CHANSON, H. (2017). "Self-aeration in Smooth and Stepped Chutes." Environmental Fluid Mechanics, Vol. 17, No. 1, pp. 27-46 (DOI: 10.1007/s10652-015-9442-z).