Evacuateurs de Turkwel et de Katse

Turwel and Katse spillways

Ingénieurs hydrauliciens SOGREAH

Abstract

This article presents the particular design features of the surface spillways and bottom outlets of Katse and Turkwel, two arch dams in Africa. For the bottom outlets, the design involves throttling the water stream at the outlet by converging side walls, allowing the impact zone to be spread out over a wider area and further from the dam, thereby improving energy dissipation. For the Katse surface spillway (170 m head), the design includes a very long chute (30 m head), accelerating the water to very high speeds to spread the stream flow and move the jet impact further away from the base of the dam. Improved aeration combined with flow dividing blocks increase water stream break-up and jet atomisation. The combination of these specially designed systems enhances energy dissipation and minimises scour effects downstream of the dams.