2013 – Design considerations for the Kashimbila Multipurpose Dam and hydropower station

Bertrand Rochecouste Collet, Dawid van Wyk and Emmanuel Adanu

The preliminary design of the Kashimbila Multipurpose Dam on the Katsina-Ala River in the Taraba State, Nigeria was initially focussed solely on it functioning as a buffer dam in the case of failure of the natural embankment of Lake Nyos in Cameroon. The failure of Lake Nyos could generate an extreme flood endangering the population in south-eastern Nigeria. As the design process progressed with a more holistic and multipurpose approach, the capacity of the dam was increased to provide irrigation and potable water to the surrounding towns and villages, as well as the generation of hydropower. The dam is a composite structure consisting of a mass concrete gravity uncontrolled spillway, a clay-core rockfill embankment, a 40 MW hydropower station and an outlet works with twin 1.4 m diameter pipes feeding the irrigation pumpstation and water treatment works. This paper covers the design considerations of the Kashimbila Multipurpose Dam and Hydropower Station, with particular emphasis on hydrological challenges and related design solutions.