HOW THE LAKE WAS CREATED
ECOLOGY AND WEATHER
SSSSSSIn the ’40s the Federation of Rhodesia and Nyasaland (now Zimbabwe, Malawi and Zambia) looked for ways to generate electricity for copper mines.
In 1955 plans were made to build a hydroelectric dam at one end of the Kariba Gorge, a natural valley through which the Zambezi River flowed.
Hydroelectricity is generated by harvesting the force of falling water. Water released through the floodgates of a dam spins the blades of a giant turbine, which is connected to a generator that makes electricity as the blades spin.
The dam was designed by French engineer and inventor André Coyne and built by Italian construction company Impresit.
The building of the dam caused the Zambezi River to flood the Kariba Gorge – a controversial decision that displaced 57 000 Batonga people living along the river. During construction 86 workers died. The dam was completed in 1959 and the lake was filled by 1963. Queen Elizabeth the Queen Mother, mom of Britain’s current queen, officially opened the dam in 1960. The name Kariba comes from the word “kariva”, which means “trap”. The mass of the water in the lake. This enormous weight has caused 20 earthquakes in the area with magnitudes of more than five on the Richter Scale. The weight of the water puts pressure on faults in Earth’s crust. The change in pressure when water flows into the lake and then pours out through the floodgates can lead to sudden movement along the faults, which can cause earthquakes.
SSSZambezi Valley Zambezi River flowing out
The flooding of the Kariba Gorge put thousands of wild animals in the area at risk. Operation Noah was launched to save them. Led by conservationist Rupert Fothergill, who later had an island in Lake Kariba named after him, the operation rescued more than 6 000 animals caught on islands formed in the lake by flood waters.
The animals rescued included elephants, rhinos, lions, zebras, antelopes, warthogs and snakes. They were relocated to Matusadona National Park on the southern shore of the lake.
Before the lake was flooded, the vegetation in the gorge was burnt to create a thick layer of fertile soil that formed the lake bed. This created the base for an ecosystem in the lake and allowed fish species to be introduced, such
SSS579m Floodgates 128m Plunge pool The double-curvature arch dam wall made of concrete was built on a bed of basalt rock that seemed solid. But water released through the floodgates over the past 50 years has eroded this rock bed, creating a 91m-deep pit called a plunge pool underneath. Since the ’60s only three of the six floodgates have been opened at a time for fear of enlarging the plunge pool.
Engineers warn that without urgent repairs the wall could collapse, unleashing a tsunami through the Zambezi Valley that could reach the Mozambique border in just eight hours.
This could knock out 40% of Southern Africa’s hydroelectric capacity and put 3,5 million lives at risk. In November 2017 it was reported that a $294 million (R3,5 billion) repair project, to be completed by 2025, is on track. as the kapenta which supports a commercial fishery and provides food for sea eagles and cormorants. Gamefish such as tigerfish attract tourists. Crocodiles and hippos also live in the lake. WEATHER
Lake Kariba is generally hot all year round. The area is at its most humid during the rainy season from October to April when short, intense thunderstorms are interspersed with periods of bright sunshine.
During August and September there’s lots of wind, which makes the lake quite choppy – so it’s not a good time to visit if you get seasick.
The best time to visit Lake Kariba is during May and July when the weather is dry, calm and slightly cooler.