ABSTRACT
A dam spillway consists of three distinctly different portions, namely the: overflow zone or headworks; chute zone or transport structure; and terminal zone or outlet and dissipation structure. The chute has become an important dam appurtenant structure once dam heights are increased over several tens of meters. Spillway chutes and tunnels represent important appurtenant hydraulic structures at dams regarding their safety. Floods are evacuated from reservoirs by the spillway chute, so it is an important dam safety element. On spillway chutes, cavitation damage typically occurs on the invert but rarely along the sidewalls, so that invert aeration is often sufficient. The layout of stepped chutes is similar to that of smooth chutes on concrete gravity dams, consisting of control structure, spillway chute and terminal structure. Stepped chutes do not mandatorily include smooth concrete surfaces, but can involve rough faces as gabions or damaged concrete, for instance.
