Design review of the headrace system for the Upper Tamakoshi project, Nepal

One way to reduce the cost of construction of hydroelectric projects with underground waterway systems is to allow the rock mass to act as natural concrete and to adopt unlined/shotcrete-lined pressure tunnels to the extent that the rock mass permits. This article reviews engineering geological design aspects and design changes adopted for the headrace system of Upper Tamakoshi hydro project in Nepal, as more studies were done to increase knowledge of the geological characteristics of the rock mass and in situ stresses in the project area.