The Zambezi ­ Reservoirs of Water:
Dams on the River

#3 in a Series by Cecil Keen

The Zambezi River begins in northwestern Zambia and starts by twisting north and then south for 190 miles before it crosses into Angola. It then reemerges into Zambia about 100 miles north of the town Zambezi while flowing across the Kashiji Plain. Shortly thereafter two tributaries join the main stream in a swampy remnant of a once previous inland sea. Downstream of the swamp another two tributaries join the main flow and the Zambezi continues its southern journey across the Barotse Plain. At the first of many cracks in the basalt plateau, the river falls over a series of rapids and water falls, and changes direction to the southeast. For about 60 miles (90 km.) it flows through a gorge and suddenly emerges onto the Siloana Plains of south-western Zambia, where it broadens in width to become a meandering river - in some areas measuring more than 2 miles wide. At another series of cracks, it rolls over the Kasanga Rapids and then the Mpandwa Rapids and takes another sharp turn (at Katima Malilo) giving it from here onwards an easterly flow to the sea.

The town of Katima Malilo is the border town between Zambia and Namibia (Caprivi Strip). For the next 60 miles (90 km.) the Zambezi meanders through swampy terrain, teeming with wild animal and bird life and marks the northern border of Namibia's Caprivi Strip. At the eastern tip of the Caprivi Strip a southern tributary, the Chobe River, joins the Zambezi. This river is part of the Okavango Delta ­ a complex of inland flowing rivers and another remnant of one of Africa's vast inland seas. The town of Kazungula exists at the confluence of the Chobe and Zambezi rivers and is also the boundary point between four countries - Zambia, Namibia, Botswana and Zimbabwe.

For the next 40 miles (64 km. ) the river broadens and slows in its way towards the complex of zigzag faults that form the Victoria Falls (see Part 2). After dropping a spectacular 300 feet (90 m.) at the Victoria Falls, where it forms one of the seven ‘natural wonders of the world', the river flows through a series of zigzag gorges which, in ages past, the water-falls used to be. Twenty-five miles downstream from the Victoria Falls the river flows over a series of 19 rapids (some as narrow as just 40 feet) through the Batoko Canyon. At the end of this 20-mile canyon the river drops another 40 feet through the Moemba Falls. Alternating for the next 80 miles (128 km) between gorge and unconfined river flow, the Zambezi flows into what is now Lake Kariba ­ a lake created by one of two hydroelectric dams the Zambezi now supports.

Kariba Dam/ Lake Kariba:

For many years after its completion in 1959, Lake Kariba was the largest man-made lake in the world. The dam was opened on May 17, 1960 and built to provide hydroelectric power to Zambia and Zimbabwe. The lake has a surface area of 3,000 sq. miles (5,000 sq. km.), a maximum depth of 380 ft. (116 m.) and extends to a length of 175 miles (282 km.) with an average width of about 20 miles (32 km.). The dam wall took more than 1.25 million cubic yards (1.05 million cubic meters) of concrete and stands 420 ft. (128 m.) high. The crest of the wall is 2,025 ft. long (617 m.). While no longer the largest dam in the world, it is still among the largest hydroelectric structures, generating 705 MW of electricity for two countries in Central Africa. A road across the top of the dam links Zambia and Zimbabwe.

In 1967 a sardine like fish, Kapenta (Limnothrissa Modan) was introduced into Lake Kariba to alleviate the food shortage in Zambia. The project eventually became successful in that the sardines multiplied at an excellent rate ­ but, with a significant alteration to the ecology of the Lake. The Tiger fish of Kariba started instead to feed on the Kapenta in the deeper waters and left the Bream alone. By 1969 it was recognized that Kapenta was a valuable and viable food source and a pilot scheme was set up to catch the fish. There were good and bad months and eventually a large commercial fishing operation was given a license to catch the fish as a commercial enterprise. After some trials and errors Pursein nets, dip nets and lift nets were all approved and are presently used by both the public and commercial operators in a growing fish business.

Kapenta are light-attracted fish, with adults averaging 4-5 cm long. Their protein content is exceptionally high at 62%. The once black skies and magnificent views of the Milky Way from the shores of Lake Kariba are a thing of the past. The surface of the Lake is dotted with fishing rigs aiming powerful floodlights into the water to attract the fish to be caught in the various fishing nets. Not only is the Lake affected by ‘light pollution', there is also the incessant groan of boat engines and generators pervading the night hours as the fishing continues 7 days a week! There are seasonal fluctuations in the Kapenta catches, related to the extra nutrients brought down following the rainy season, reaching a peak fish density in July and August. With so many fish, food then becomes a problem and results in a collapse of the Kapenta population and by September and October there is a scarcity and the price of the fish goes up accordingly. This food has now become part of the staple diet for many of the people of both Zambia and Zimbabwe. It is sold at all grocery stores and is available on most menus at hotels and restaurants in these central African nations.

Downstream from Kariba: Mana Pools

The Zambezi River continues to be the border between Zambia and Zimbabwe for another 200 miles from Kariba. The main road linking Zimbabwe to Zambia and the north crosses the Otto Beit Bridge at Chirundu where the river is confined in a relatively narrow gorge. About 30 miles further downstream the Zambezi is joined by Zambia's other significant river the Kafue. Seasonally, a significant amount of water is added to the Zambezi's flow at this point and the river swells considerably. The river flow downstream is again confined within gorges interrupted by occasional wide unrestricted stretches. The various governments who share the river have declared National Parks or Wild Life refuges at significant spots along its course. One such place is the Mana Pools National Park of Zimbabwe, an area of 848 sq. miles (2,196 sq. km.) about 45 minutes flight time downstream from Kariba and about 40 miles from the confluence of the Kafue River. It is a recreation area where animal life can be viewed from canoes on the river, or on foot and motorized safaris run from camps on the southern shores of the Zambezi.

Eastwards of Mana Pools the river becomes confined to a narrow gorge (the Mupata Gorge) and continues this way for nearly 40 miles until another tributary joins it from the north, the Luangwa River. The Luangwa is one of the larger rivers feeding into the Zambezi. It joins the flow at the Mozambique border with Zambia and Zimbabwe. Three towns mark the border post: Luangwa (Zambia), Kayemba (Zimbabwe) and Zumbo (Mozambique). Within a few miles of Zumbo, the Zambezi begins to broaden significantly with the Cabora Bassa Reservoir (dam) now stretching back 168 miles from its wall.

Cabora Bassa Reservoir (Dam)

Above is an infrared satellite view of Cabora Bassa. The Zambezi flows into the dam at the bottom left of the picture. (Red in the picture is green foliage)

Completed in 1974, Cabora Bassa is rated as the fifth largest dam in the world and has the potential to become the continent's largest hydroelectric supplier with a capacity of 3,870 MW of electricity. However, damage to the generators during the civil war has kept the power plant from functioning at the expected level. The lake, with five basins, lies along a west-east axis almost parallel to the prevailing southeasterly winds. What is it like to paddle across the great expanse of Cabora Bassa in a small boat? Nancy Farmer takes us there in her 1996 book for young adults, A Girl Named Disaster*.

    The Shoreline had completely vanished. This was no side channel. . . The boat had been scooped up and dropped into a boundless ocean. . . As the breeze freshened, small ripples became wavelets; the wavelets grew into swells. If she tried to rest, the craft swung sideways with a terrifying seesaw motion. . . Her head swam with fatigue; the sunlight glittering off the water made her eyes ache. A dip in the waves revealed the top of a rock . . . Suddenly, white foam frothed all round her as other rocks made their presence known.

Waves over Rapids and more!

Beneath the surface of the lake lie the once treacherous Cabora Bassa rapids, the impediment to Livingstone's plan to use the Zambezi as ‘God's Highway' to the interior. The name comes from a local word, kebrabassa, meaning ‘where the work ends' ­ the last navigable point going upriver from the coast. Not until 1880 did a European successfully navigate the rapids.

The lake may also conceal the lost silver mines of Chicova. Legends tell of a rich vein of silver downstream from Zumbo that supplied more than 1,000 pounds of the metal to the Portuguese outpost at Sena in the 1600s. The exact location of the mines remains a mystery.

Cabora Bassa has a surface area of 1,057 sq. miles (2,739 sq. km., a maximum depth of 515 ft. (157 m.) and a mean depth of 68 .5 ft. (20.9 m.). Like Kariba, Cabora Bassa is utilized as a source of water, for navigation and transportation, fishing and power generation. In recent months, new power lines have been completed and the generators have been repaired. The Portuguese-owned Company Hidroelectrica de Cabora Bassa (HCB) which runs the dam is still in negotiation with South Africa's ESCOM (Electricity Supply Commission) over what tariff to charge for the electricity. There are also plans being discussed to build another dam at Mepanda Uncua, 43 miles (70 km.) downstream from Cabora Bassa. It would have an output up to 2,500 MW, have its own transmission lines (again to Maputo and on to South Africa), and cost over $1,500 million to build. Even if it were started it could not be finished before 2007 and in the meanwhile Cabora Bassa's output would be doubled to 4,000MW by the installation of further generators. Everything appears to be hanging on ESCOM's appetite for power, and if the price is right!

To the sea:

The river is wide and continues to widen as it begins to flow across the coastal plain of Mozambique. One of the earliest trading centers in the southern African interior was the town of Tete. Muslim traders from the port of Safala occupied it, at least as early as the 1300s. Portuguese adventurers moved into the area in the early 16th Century. A cathedral in Tete, along the banks of the Zambezi, dates to shortly after that time. Until the 18th Century it was the furthest inland outpost of the Portuguese.

Tete suffers some of the hottest temperatures of any town in southern Africa ­ 122°F in the summer. With no tourist attractions to speak of, its growth has been slow. However, with the building of the Tete Suspension Bridge in the late 1960s, across the Zambezi, the town is a hub of transport routes connecting northern and southern parts of the country.

From Tete the Zambezi continues its descent towards the sea and becomes navigable for ocean sized vessels. Several towns have grown along its banks capitalizing on the commercial opportunities the river offers. Both roads and rails parallel the river from Dona Anna to the coast and the river finally ends its journey entering the Mozambique Channel in a large delta. This delta is a labyrin th of channels over 60 miles wide. The sands of the delta shift with the advance and recession of the wa ter, causing constant changes in the position of small islands. There are four species of mangrove trees that flourish in the delta ­ these unique trees with their exposed root syst ems draw nutrients directly from the air.

Entering the Ocean:

The port city of Quelimane has served Zambezi River traffic since Muslim traders discovered a navigable channel, which directly connected to th e larger river at wha t is now Mopeia. Gold, ivory, and slave s were loaded into ocean going ships bound for foreign ports. Later sugar, fish, copra and rice took over as exports. Today , the river is dredged of the sand, which would ground freight vessels, and the fishing trawlers that frequent the port.

In the mid 19th Century, the delta was twice its present width. It once extended north nearly to Quelimane. The harnessing of the river's power with the Kariba and Cabora Bassa dams reduced the size of the area flooded by the Zambezi.

The Zambezi in summary:

The waters of the Zambezi which began their journey in the highlands of northern Zambia, plunged over cataracts and water falls, burst across plateaus and plains, and swelled behind colossal concrete dams, finally enter the Mozambique Channel with barely a ripple in its journey of life.

Through the 1,653 miles (2,660 km.) of its life the Zambezi River brings sustenance to both animals and humans. It is used to drink, it is used to irrigate, its energy is captured for hydroelectric power, and its fish are consumed for their protein. The banks and surfaces of the river are used for recreation and enjoyed for the viewing of the variety of animal populations that also depend on the river for life. The Zambezi River is unquestionably central Africa's River of Life.

Note: A Timely Reference Experience: A journey from source to mouth has recently been completed by a group of people known as the ZZAM team. The last Journal entry (#74), by Chris Walton, is a worthy footnote to understanding the Zambezi. This can be read at the Internet reference: http://www.zzam.org/Full/Expedition/Journal/Entries/Entry74.htm

* Farmer, Nancy: A Girl Named Disaster, New York, Orchard Books, 1996

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