Lesotho Highlands water project - design of the 'Muela hydropower station

A 72 MW hydropower station is included in phase 1A of the Lesotho Highlands water project to allow Lesotho to become self-sufficient in energy production, This paper describes the design of the 'Muela underground power station and regulating reservoir formed by a 55 m high dam. Features include the accommodation of hydraulic transients arising in the 45 km long upstream tunnel, the changes made in the dam to take account of a thin clay layer in one abutment and the special consideration given to the provision of a bypass to allow water transfer to take place when the station is out of commission.