Gibe III Hydropower Project

The Gibe III Hydropower project is approximately 450 km south-west of the capital Addis Abeba on the banks of the Omo River.

The works involved the design and construction of the tallest RCC dam in the world at the time of its completion, and an open-air power plant with 10 Francis turbines, which have a total installed power of 1,870 MW and an expected energy output of 6,500 GWh per year.

The project also involved three diversion tunnels and two twin adduction tunnels, two intake structures, two horizontal tunnels, four vertical shafts and two distributors.

The project is the natural extension of the biggest complex along the Gilgel Gibe River with the two other hydroelectric dams Gibe I (completed and operational since 2004) and Gibe II (operational since 2010).

The works involved a RCC dam (Roller Compacted Concrete) 250 m high, the first of its kind in the world, with a crest length of 630 m and a total volume of 6,214,000 m³ of concrete.

The project also included a 7-span spillway with radial gates and two halfway outlets; two adduction pressure tunnels, with a section lined in concrete with a diameter of 11 m and a total length of about 2 km, two intake structures; two shafts each approximately 126 m deep for the movement of the gates, two balancing shafts 140 m high and with an excavation diameter of 27 m, two pressure pipes with steel lining, inclusive of two vertical shafts about 110 m deep, and two collectors each with 5 lines; a 400 KV substation. 

The river diversion operations included diversion tunnels (a 3.2 km-long tunnel), an upstream cofferdam, about 600,000 m³ in volume, and a downstream cofferdam. Other permanent works covered by the contract were a bridge over the Omo River and camps and facilities for the client. 

The plant forms a reservoir with a surface area of 200 km2 with a storage capacity of 14,000,000,000 m³.

Client: Ethiopian Electric Power