Kariba Dam

The Kariba Dam is a massive double curvature concrete arch dam. It is located in the Kariba Gorge within the Zambezi river basin. This structure sits on the border between Zambia and Zimbabwe. By blocking the flow of the Zambezi River, the dam creates Lake Kariba. This reservoir is a vital source of electricity for much of Southern Africa.

This dam generates power through hydroelectricity. Hydroelectricity is the process of using moving water to create electrical energy. The dam features two separate power stations on opposite sides of the river. The Kariba South station belongs to Zimbabwe and has operated since 1960. It originally used six generators with a capacity of 150 megawatts each. The Kariba North station belongs to Zambia and began operating in 1976. This station uses four generators with a capacity of 100 megawatts each.

Construction of the dam was a complex and expensive undertaking. It was ordered by the Government of the Federation of Rhodesia and Nyasaland. This was a federal colony within the British Empire. The project was led by consulting engineers from several firms. These included Sir Alexander Gibb & Partners and Coyne et Bellier. The first stage of construction took place between 1955 and 1959. This initial phase cost $135,000,000 and focused on the South power cavern.

Political issues delayed the completion of the entire project. The addition of the Kariba North Power cavern was not finished until 1977. The total cost for the entire project reached $480,000,000. Construction was also dangerous for the people building it. During the building process, 86 construction workers lost their lives. Queen Elizabeth the Queen Mother officially opened the dam on 17 May 1960.

The creation of the lake caused major environmental and social changes. The rising water forced the resettlement of about 57,000 Tonga people. These people lived along the Zambezi on both sides of the river. Many people have different views on the aid provided to them. Some writers, like Jacques Leslie, described it as a major disaster. To save wildlife, people started Operation Noah from 1958 to 1961. They rescued around 6,000 large animals from the rising waters.

Engineers have recently faced serious concerns about the dam's structural integrity. The water from the spillway has caused erosion on the bedrock. This erosion carved a large crater that undercuts the dam's foundations. If the dam were to fail, a wall of water could reach the Mozambique border in eight hours. This event could affect 3.5 million people and 40% of southern Africa's hydroelectric capacity. To prevent this, the Kariba Dam Rehabilitation Project began in 2017. This project aims to fix the plunge pool and the spillway gates by 2025.

Climate and water levels also impact how the dam works. In 2016, water levels dropped to just 12% of the reservoir's capacity. Low rainfall and heavy water use can cause power shortages. In early 2023, an energy crisis caused levels to fall to 1% capacity. Because of these challenges, some suggest building a 250 MW floating solar plant. This would help make the electricity supply more reliable for the region.