ABSTRACT
Energy dissipation is particularly important at the base of high dam structures. Usually, the energy dissipation takes place at a well-defined location, such as a stilling basin, a dissipation chamber or even a plunge pool. Various types of drop structures have been developed such as: the single and the cascade drop. This chapter considers the very rough channels as appear in mountains. It focuses on cascade drops and presents a design equation. Baffled apron drops constitute a well-defined drop structure. Uniform flow in a rough channel in achieved only in an average sense, and is therefore not comparable to the phenomenon occuring in smooth pipes or channels. In a drop, the impact of flow is an essential element of energy dissipation, whereas what is called skimming flow may occur over steps. The multiple rows of baffle blocks on the chute prevent excessive acceleration of the flow and provide a suitably low terminal velocity, regardless of the height of drop.
