The Kariba Dam is a dual-curve (curves both horizontally and vertically) concrete arch dam- that curves upstream in the Kariba Gorge of the Zambezi River basin between Zambia and Zimbabwe. Arch dams are designed such that the water pressing against them compresses and strengthens the structure as it pushes into its foundations. The dam stands 128 meters (420 ft) high, 579 meters (1,900 ft) long and 13 meters (43 ft) wide at its crest, and 24 meters (79 ft) wide at the base. Lake Kariba, formed by the Kariba dam, is the largest man-made lake in the world, which extends for 280 kilometers (170 mi) and can hold back 185 cubic kilometers (150,000,000 acreft) of water.

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Overview of the dam_©httpswww.lifegate.comkariba-dam-power-crisis

Why the name Kariba?

The name Kariba was derived, by Europeans from the regional Shona word ‘kariva’ or ‘kariwa’ meaning ‘little trap’ or ‘bridge’. One of the many explanations for this is that before the dam was erected, the Zambezi River, at this ravine was channeled into a narrow corridor not more than 100 meters wide. The mighty water sculpted its way through a big granite block, leaving the top to form a natural bridge. The incident has various mythological stories affiliated with it. This arch appeared like a large traditional fish trap, hence the denotation.

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The river basin and the dam_©httpsrazel-bec.fayat.comenmajor-projectsthe-kariba-dam-in-zambia

Lake Kariba’s construction timeline

The Kariba Dam was built across the Zambezi River between 1956 and 1959. Constructing the dam and its reservoir forced the resettlement of around 57,000 Tongan people residing along the Zambezi River in both Northern Rhodesia and Southern Rhodesia.

1955, August: The Federation of both Rhodesia & Nyasaland called for tenders for the construction of Kariba Dam;

1956, July: The tender was awarded to the Italian establishment Impresit (presently Salini Impregilo);

1956 September: Construction started with the excavation for the foundation;

1957: Rare flooding happened at Kariba ruining the equipment, and access drives;

1958: An even major flood tide megahit, destroying the access ground, coffer dam, and regions of the main wall as well;

1958: In December, the Zambezi River clogged at Kariba;

1958 to 1964: Operation Noah – a rescue operation to save thousands of creatures from the flooding of Kariba Dam;

1959, December: The first generator was commissioned;

1960, May 17th: The Kariba Hydro Electric Scheme was officially inaugurated by the late Queen Elizabeth II.

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Construction o fthe dam_©httpsrazel-bec.fayat.comenmajor-projectsthe-kariba-dam-in-zambia

Hydroelectric power generation by Kariba

Kariba is a significant source of hydroelectric power for the regions of Zimbabwe and Zambia. Zambia’s 1,080 megawatts (MW) North Bank Power Station and Zimbabwe’s 1,050 MW South Bank Power Station, also known as The Kariba Hydro Power Station get water from the Kariba Dam. The scheme supplies 1,626MW of electricity to Zambia and Zimbabwe and is shared between them where each country has its power station – one on the north bank and another one on the south bank of the dam. The Chinese firm Sinohydro, in recent years, has upgraded the two power stations by adding 360 MW to the North Bank Power Station and 300 MW to the Kariba Power Station. The Dam is conjointly operated by Zambia and Zimbabwe through the Zambezi River Authority.

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Water force at the dam_©httpsnewsaf.cgtn.comnews2023-12-31Kariba-Dam-rehabilitation-project-now-80-pct-complete-managing-body-1pUzEjWYQbCp.html

Energy crisis looms

Currently, the water levels in the dam are extremely low threatening the continuation of electricity generation at the power station. It might lead to taking severe measures such as load shedding in the country. The officials are turning towards investing in more renewable energy, which will have an impact on the generations to come.

After 56 long years of operation, there are strong concerns that the Kariba Dam could collapse. Water streaming through the floodgates has sculpted a 91m deep cavity – or plunge pool – at its foothold. The pool is around 40m from the structure’s foundation. If it reaches the foundation, the dam is likely to give way.

Rehabilitation of Kariba Dam

The Kariba Dam is currently undergoing a restoration scheme since 2017 to reshape the plunge pool and refurbish the spillway gates, for its continued safe operation. The project will extend the life of the dam and is expected to be completed by 2025. It will ensure an interminable water force for both the Kariba North power station and the Kariba South power station.

The rehabilitation project of the Kariba Dam wall is now 80% complete, as reported by the Zambezi River Authority (ZRA), a bi-national association managing the dam on behalf of the governments of Zambia and Zimbabwe. Comprising of three factors- the reshaping of the plunge pool, refurbishment of the overflow channels upstream control complex, and institutional strengthening- the project is expected to be completed by the first quarter of 2025, as per ZRA. 

As reported by the ZRA chief,  After completion, the Kariba Dam Rehabilitation Project (KDRP) will be noted in history as the first project of this magnitude ever taken over with open-pit excavation at the bottom of a 60-year-old dam with underground powerhouses on either bank of the river in full operation. 

The $294 million project is being financed by the European Union, the World Bank, the African Development Bank, the government of Sweden, and the Zambezi River Authority on behalf of the governments of Zambia and Zimbabwe, through an amalgamation of subsidies and loans.

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Refurbishment of the dam_©httpsrazel-bec.fayat.comenmajor-projectsthe-kariba-dam-in-zambia

Tracing back to its origin, the traditional tribe of Tonga knew the Zambezi and was aware that a river keeps time, not like a clock but like a chronicle. The people knew that you don’t stop a river; you move over, through, and with it. You follow its paths. You may step into it as frequently as you wish, but you do not stay.

References:

Donna Slater (2022). Kariba Dam Rehabilitation Project progressing in line with 2025 completion date. [online]. Available at: https://www.engineeringnews.co.za/article/kariba-dam-rehabilitation-project-progressing-in-line-with-2025-completion-date-2022-02-07 [Accessed 25 February 2024].

Mike Mwenda (2023). Power crisis looms in Zambia as world’s largest man-made dam dries up. [online]. Available at: https://www.lifegate.com/kariba-dam-power-crisis [Accessed 25 February 2024].

Kariba Dam. [online]. Available at: https://www.siyabona.com/kariba-dam-history.html [Accessed 25 February 2024].

Kariba Dam. [online]. Available at: https://www.victoriafalls-guide.net/kariba-dam.html [Accessed 25 February 2024].

Author

Khushi is a young architect who is always trying to look for new things to learn and experience new cultures, especially through an architectural lens. Having been an inquisitive mind, critical thinking has always been an integral part of her. She believes in the process of bringing harmony to society and nature while preserving its identity.