Science Fair Project Encyclopedia
The Zambezi (also spelled Zambesi) is the fourth longest river in Africa, and the largest of those flowing eastwards to the Indian Ocean. The area of its basin is 513,500 sq. m., slightly less than half that of the Nile. The 2,750 km long river has its source in Zambia and flows through Angola, along the border of Zambia and Zimbabwe, to Mozambique, where it empties into the Indian Ocean.
The Zambezi's most spectacular feature is Victoria Falls, one of the world's largest waterfalls. Other notable falls include the Chavuma Falls at the border between Zambia and Angola, and Ngonye Falls, near Sioma in Western Zambia. Over its entire course, the Zambezi is spanned by only four bridges: at Chinyingi , Victoria Falls, Chirundu and Tete.
There are two main sources of hydro-electric power on the river. These are the Kariba Dam, which provides power to Zambia and Zimbabwe and the Cahora Bassa Dam in Mozambique which provides power to South Africa. There is also a smaller power station at Victoria Falls.
The river rises in north-western Zambia, in undulating hills about 1500m above sea level, covered with bracken and open forest. Like that of all the rivers of the neighbourhood, the Zambezi's source is a black marshy bog, which quickly collects into a well-defined stream. In the first hundred miles of its course the river is known as the Yambeshe, in sound almost identical with its name in its lower course, though intervening sections are known as Liambeshe, Liarabai, &c. Eastward of the source the watershed between the Congo and Zambezi basins is a well-marked belt of high ground, falling abruptly north and south, and running nearly east and west between 11 and 12 S. This distinctly cuts off the basin of the Luapula (the main branch of the upper Congo) from that of the Zambezi. In the neighbourhood of the source the watershed is not so clear, but the two river systems do not connect.
The upper river
After flowing to the south-west for about 150 miles, the river turns more directly south, and is joined by many tributaries. A few miles above Kakengi , the hitherto narrow and tortuous river widens from 100 to 350m. Below Kakengi are a number of rapids ending in the Sapuma cataracts, where the river flows through a rocky fissure. The first of its large tributaries to enter the Zambezi is the Kabompo River , which joins the main stream at 14 26' S. A little further south is the confluence with the much larger Lungwebungu River . The savannah forest through which the river has flowed gives way to a more open bush valley, studded with Borassus palms. Dense vegetation is confined to narrow strips of matted forest which skirt the first few hundred yards of the sources of the Zambezi and its tributaries during the first 100 miles or so.
From 1500m at the source, the river drops to about 1100m at Kakengia , 220 miles downstream. From this point until the Victoria Falls are reached, the level of the Zambezi basin is very uniform, dropping only by another 180m. Twenty miles below the confluence of the Lungwebungu the country becomes flat, and in the rainy season is largely covered by floods. Some 50 miles farther down, the Luanginga , which with its tributaries drains a large area to the westward, joins the Zambezi. A few miles higher up on the east the main stream is reinforced by the waters of the Luena .
On the same (eastern) side a little below the junction of the Luanginga and the Zambezi stands Lealui, one of the capitals of the Lozi people . The chief of the Lozi has two compounds, the other being at Limulunga. Limulunga is on high ground and serves as the capital during the rainy season. The annual move from Lealui to Limulunga is a major event, celebrated one of Zambia's best known festivals, the Kuomboka .
The river, which for some distance has had a slight western as well as southern trend, now turns distinctly south-east. From the east the Zambezi continues to receive numerous small streams, but on the west is without tributaries for 150 miles., when the great river formerly misnamed the Chobe, but known to the natives as Kwando or Linyante, joins it. Before this junction is effected, the Ngonye Falls offer an interruption to navigation, whilst below the falls are numerous rapids.
South of Ngonye Falls, the river briefly borders Namibia's Caprivi Strip. The strip projects from the main body of Namibia, and results from the colonial era: it was added to German South West Africa expressly to give Germany access to the Zambezi.
Below the junction of the Kwando and the Zambezi the river bends almost due east. The stream has hitherto flowed, in the main, in a gentle steady current, the depth of water, owing to the breadth of the channel, not being great. But as it flows eastward towards the border of the great central plateau of Africa it reaches a tremendous chasm, into which the Victoria Falls plunge.
The middle Zambezi
The Victoria Falls are reached 60 miles after the Kwando confluence is passed, and below them the river continues to flow due east for about 120 miles. It then cuts its way through perpendicular walls of basalt from 60 to 200 ft. apart. Towering over the rocks which form the banks of the river are precipitous hills, 700 to 800 ft. high. The river flows swiftly through the gorge, the current being continually interrupted by reefs. Beyond the gorge are a succession of rapids which end 150 miles below Victoria Falls. Over this distance, the river drops 250 metres.
At this point, the river enters Lake Kariba, created in 1959 following the completion of the Kariba Dam. The lake is one of the largest man made lakes in the world, and the hydroelectric power-generating facilities at the dam provide electricity to much of Zambia and Zimbabwe.
The Luangwa and the Kafue are the two largest left-hand tributaries of the Zambezi. The Kafue joins the main river in a quiet deep stream about 200 yds. wide. From this point the northward bend of the Zambezi is checked and the stream continues due east. At the confluence of the Luangwa (15 37' S.) it enters Mozambique.
The middle Zambezi ends when the river enters Lake Cahora Bassa (also spelled Cabora Bassa). Formerly the site of dangerous rapids known as Kebrabassa, the lake was created in 1974 by the construction of the Cahora Bassa Dam.
The lower river
The lower Zambezi's 400 miles from Cahora Bassa to the sea presents no obstacles to navigation although the river is shallow in many places during the dry season. This shallowness arises from the different character of the river basin. Instead of, as in the case of the middle Zambezi, flowing mainly through hilly country with well-defined banks, the river traverses a broad valley and spreads out over a large area. Only at one point, the Lupata Gorge , 200 miles from its mouth, is the river confined between high hills. Here it is scarcely 200m wide. Elsewhere it is from 3 to 5 miles wide, flowing gently in many streams. The river-bed is sandy, the banks are low and reed-fringed. At places, however, and especially in the rainy season, the streams unite into one broad swift-flowing river.
About 100 miles from the sea the Zambezi receives the drainage of Lake Malawi through the Shire River. On approaching the ocean, the Zambezi splits up into a number of branches and forms a wide delta. Each of the four principal mouths, Milambe, Kongone, Luabo and Timbwe, is obstructed by a sand-bar. A more northerly branch, called the Chinde mouth, has a minimum depth at low water of 7 ft. at the entrance, and of 12 ft. farther in, and is the branch used for navigation. Sixty miles farther north is a river called the Quelimane , after the town at its mouth. This stream, which is silting up, receives the overflow of the Zambezi in the rainy season.
The delta of the Zambezi is today about half as broad as it was before the construction of the Kariba and Cahora Bassa dams controlled the seasonal variations in the flow rate of the river.
The region drained by the Zambezi is a vast broken-edged plateau 3000 or 4000 ft. high, composed in the remote interior of metamorphic beds and fringed with the igneous rocks of the Victoria Falls. At Shupanga, on the lower Zambezi, thin strata of grey and yellow sandstones, with an occasional band of limestone, crop out on the bed of the river in the dry season, and these persist beyond Tete, where they are associated with extensive seams of coal. Coal is also found in the district just below the Victoria Falls. Gold-bearing rocks occur in several places.
The Zambezi has numerous tributaries. Some of the more important ones are described here, in order from source to sea.
The Kabompo rises in the high land which forms the eastern watershed between the Zambezi and Congo systems. It is formed itself by the confluence of the upper Kabompo and the somewhat larger Lunga River , and flows into the Zambezi north of the town of Lukulu .
The Lungwebungu , which enters the Zambezi from the west just south of the confluence with the Kabompo River, is a strong, deep stream 200m wide in its upper course, flowing in a valley bordered by white sand covered by thin forest, its floor forming at times an inundated plain 2 to 3 miles wide.
The Cuando River, largest of the western affluents of the Zambezi, was formerly known as the Chobe, a name now given to another tributary. The Kwando has the ruined capital of the Makololo people on its lower course. It rises in Angola, and flows in a generally straight course south-east, forming the border between Zambia and Angola for part of its course, before making a sudden bend to the south, then flowing east to the Zambezi. In this eastward stretch the Kwando flows through a vast reedy swamp or lake studded with alluvial islands for 70 miles. Apart from its head-streams, it receives most of its tributaries from the west, and at its most southern bend is joined by the Magwe'-kwana, which in time of flood receives some of the surplus water of the Okavango. This surplus water, received after most of the flood water of the Kwando has passed, raises the level of the lake and holds up the waters of the Kwando for some miles above it.
The largest tributary of the middle Zambezi, the Kafue, rises in northern Zambia at an elevation of 1350m in thick forest country. The main headstream, which flows first south-east, then south-west, is later joined by the Lunga or Luanga, the united stream then flowing first south, afterwards due east. The Itezhi-Tezhi Dam is an important source of hydroelectric power from the Kafue river, and the river also supports a great deal of wildlife, which is protected by Zambia's largest national park, Kafue National Park . The lower Kafue has a series of waterfalls and cataracts, dropping several hundred feet in 15 miles.
The next great tributary to the east is the Luangwa which in its upper course runs parallel to the western shores of Lake Malawi, having its source not far from the north-west corner of the lake. The main stream flows in a generally level valley, bounded by steep plateau escarpments, and is for the most part shallow and rapid, though fairly wide. Its tributaries the Lunsefwa and Lukosasi drain a large extent of the western plateau of Zambia. The Luangwa joins the Zambezi a little above the town of Zumbo. The Luangwa Valley is an important wildlife conservation area, and contains North Luangwa National Park and South Luangwa National Park .
For some distance its lower course forms the border between Mozambique and Zambia. From the south the middle Zambezi receives various rivers which water northern Zimbabwe - the Shangani , Sanyati , and Hanyani , besides minor streams. The Mazoe, which rises in Mashonaland , joins the Zambezi below the Cahora Bassa Dam.
Exploration of the River
The Zambezi region was known to the medieval geographers as the empire of Monomotapa and the course of the river, as well as the position of Lakes Ngami and Nyasa, was filled in with a rude approximation to accuracy in the earlier maps. These were probably constructed from Arab information.
The first European to visit the upper Zambezi was David Livingstone in his exploration from Bechuanaland between 1851 and 1853. Two or three years later he descended the Zambezi to its mouth and in the course of this journey discovered the Victoria Falls. During 1858-60, accompanied by Dr (later Sir) John Kirk, Livingstone ascended the river by the Kongone mouth as far as the Falls, besides tracing the course of its tributary the Shire and discovering Lake Malawi.
For the next thirty-five years very little exploration of the river took place, but in 1889 the Chinde channel north of the main mouths of the river was discovered. Two expeditions led by Major A. St Hill Gibbons in 1895-6 and 1898-1900 continued the work of exploration begun by Livingstone in the upper basin and central course of the river. Portuguese explorer Serpa Pinto examined some of the western tributaries of the river and made measurements of the Victoria Falls in 1878.
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