A dam is an artificial or natural barrier that impounds water or underground streams, and its primary purpose is retaining water. The reservoirs created by dams not only suppress floods but also provide water for agriculture and power generation. Dams can be constructed using a wide range of materials, including steel, timber, and mud.
Dams have a history that goes back several thousand years. In ancient Mesopotamia, dams primarily served the purpose of controlling the water level of important rivers, such as the Euphrates. In Africa, the Sadd-el-Kafara Dam, built around 2700 BC and located 25 km south of Cairo, is reputed to be the oldest. In modern times, several important dam projects have been commissioned across the continent. Below are the 5 biggest dams in Africa:
1. Grand Ethiopian Renaissance Dam, Ethiopia
Photo credit: venture Africa
The Grand Ethiopian Renaissance Dam (GERD), also known as the Hidase Dam, is a gravity dam on the Blue Nile River in Ethiopia. Construction work on the dam began in April 2011, and engineers expect the project to be completed by July 2017. The dam’s reservoir has an area of 1,561 square kilometers and a storage capacity for 79 billion cubic meters of water. Built by an Italian construction firm at an estimated cost of $5 billion, on completion, the dam is expected to generate 6,000 MW of electricity, making it the largest hydroelectric power plant in Africa.
2. Aswan Dam, Egypt
Photo credit: Mbarron
The Aswan Dam or Aswan High Dam is an embankment dam built across the Nile. Constructed between 1960 and 1970, it has an estimated cost of $1.2 billion by Russian engineers alongside their Egyptian counterparts. The Aswan Dam is 3,830 meters long, 980 meters wide at the base, 40 meters wide at the crest, and 111 meters tall. Its reservoir can hold 132 cubic km of water.
The multipurpose dam serves to generate electricity, control floods, and irrigate thousands of hectares of farmland. Following the 1952 Egyptian revolution, a government developmental blueprint considered a dam pivotal to the country’s industrialization ambitions.
3. Kariba Dam, Zambia/Zimbabwe
Photo credit: newsday zimbabwe
The Kariba Dam is a double curvature concrete arch dam in the Kariba Gorge of the Zambezi River Basin between Zambia and Zimbabwe. Constructed between 1955 and 1959, the total cost of the dam was $480 million by Italian construction firm Impresit.
The Kariba Dam generates 6,400 gigawatt hours per annum and supplies 1,626 megawatts of electricity to parts of both Zambia and Zimbabwe. Each country has its own power station on the north and south bank of the dam.
At 128 meters high and 579 meters long, its reservoir has a water holding capacity of 185 cubic kilometers. The dam forms Lake Kariba, which extends outward for another 280 kilometres.
4. Akosombo Dam, Ghana
Photo credit: Cityfmonline
The Akosombo Dam, also known as the Volta Dam, is an embankment dam on the great Volta River in southeastern Ghana. Built between 1961 and 1969 at a cost of $258 million by Italian firm Impreglio, the dam was built primarily to supply hydroelectric power to Ghana’s aluminium smelting industries.
The dam has a height of 114 meters, a length of 660 meters, and a width of 366 meters. Its reservoir has a water holding capacity of 7,900,000 cubic meters. The construction of the dam resulted in the flooding of parts of the Volta River Basin, which led to the creation of Lake Volta.
Lake Volta holds the record as the largest man-made lake in the world by surface area. It covers 8,502 square kilometres, a significant 3.6 percent of Ghana’s total land area.
5. Katse Arch Dam, Lesotho
Photo credit: African Reservations
The Katse Dam is Africa’s second largest. It is a concrete arch dam on the Malibamat’so River in Lesotho. The dam, which was completed in 1996, was built at a total cost of $8 billion by an international consortium of design and engineering firms, including Bouygues, Concor, Group 5, Hochtief, Impregilo, Kier Group, and Sterling International.
The Katse Dam was built mainly for irrigation and domestic purposes. It currently supplies about 30 cubic metres of water to neighboring South Africa, which pays Lesotho $35 million per year. The dam has a height of 185 meters and a length of 710 meters. Its reservoir has a holding capacity of 1.95 cubic kilometres.