Tekezé Dam

BW

The Tekeze dam in the Ethiopian province of Tigre is since February 2009 with 188 m height, the highest dam in Africa. She stands in around 1000 m altitude on the eastern slope of the Ras Daschän Massif, the highest mountain with 4533 m of Ethiopia, and impounds Tekeze, a tributary of the Atbara, which flows into the Nile. It exceeds in height the 185 -meter-high Katse Dam in Lesotho, but will in turn surpassed by the already under construction dam Gilgel Gibe III.

Description

The Tekeze dam is used primarily in power generation. It has a catchment area of ​​30,390 km ² with an average annual rainfall of 850 mm, which, however, almost exclusively focused on the rainy season in the months of July, August and September. The reservoir fills the narrow and winding mountain valley of Tekeze over a length of 70 km. Its storage capacity is a maximum of 9,310 million cubic meters, of which 5,343 million cubic meters can be used for the operation of the power plant.

The double-curved arch dam concrete is 188 m high and has a crest length of 420 m. It is 5.6 m thick at the base and 28 m at the crown. The concrete work for the dam lasted 36 months. Has at approximately half the height of the four lower discharge gates to a cross section of 8 x 5.6 m.

From the 75 -meter-high intake structure, the water flows through penstocks and a vertical pressure shaft into a cavern with four Francis turbines with a capacity of 75 MW. About a switchyard and a 105 km long high voltage line of electricity in Mek'ele is fed into the Ethiopian power grid.

Details of the construction process

Before the construction of the dam had first to be created, a 40 km long access road. Then the river was diverted into two tunnels with 7.0 and 7.8 m in diameter and lengths of 430 and 370 m. To save costs, the tunnels were measured only on the basis of small amounts of water the dry season. In the originally foreseen major tunnel cross sections and broad drain gates in the dam has been omitted. Instead, the concrete work in the lower part of the dam are staggered so that three Betonierblöcke were significantly lower than the others. During the flood period of 2006, the flood flowed from this deeper Betonierblöcke without causing significant damage. For the flood period in 2007 had been left open two Betonierblöcke in the now higher dam. This was already started before serving first as a heavyweight dam the lower part of the dam with the filling of the reservoir, while the concreting progressed further. The next high tide was flowing 81 days long from over the two Betonierblöcke and the small diversion tunnel, with up to 1,313 m³ / s poured into the gorge below the dam. The surfaces of the concrete culverts suffered only slight damage caused by cavitation, which could be eliminated easily in the course of further work.

Through these operations, the filling of the reservoir could be much earlier than usual completed and the electricity begin earlier.

Party

In 1995, the site of the project was selected and created the preliminary planning phase. In 1998 the engineering firm MHW with the revision of these designs and the plans for the dam. 2002 it was announced that the government Ethiopian Electric Power Corporation ( EEPCo ) had a joint venture of several Chinese and an Ethiopian company awarded the contract for the project. The joint venture included SINOHYDRO - CWHEC, CGGC, China Wanbao Engineering Corp., JPPC and CCC. . Supplier of the turbines was Dongfang. Among the losing bidders were Strabag, Salini Impregilo, Kajima, Enka and Skanska.

The $ 365 million estimated cost of the project ( including planning, construction management, etc.) were supposed to be entirely financed by Ethiopia. Some assume, however, that cheap Chinese loans played a significant role.

Ethiopia was the 2009/10 nor more hydropower plants inaugurate: Gilgel Gibe II with 420 MW and Tana Beles 460 MW. Current, which is not used in Ethiopia, is to be exported to Djibouti.