The Zambezi River

by Mike Cadman

The Zambezi River

The Zambezi River is one of Africa’s great rivers, flowing through five countries and drawing water from a catchment area bigger than that of the Mississippi River in America, an area twice the size of France.

The Zambezi forms Zimbabwe’s entire 770 km northern border with Zambia, a stretch of river that boasts the spectacular Victoria Falls and some of Africa’s best wildlife areas. Lake Kariba, one of the world’s largest artificial lakes by volume, is a major landmark on this portion of the river and its waters comprise about 230 km (142 miles) of the border.

No fewer than four of Zimbabwe’s 11 national parks, the Zambezi N.P., Victoria Falls N.P, Mana Pools N.P and Matusadona N.P (which is on the shores of Lake Kariba), are located on the Zambezi. Almost the entire 770 km of riverfrontage on the Zimbabwean side of the river is devoted to wildlife.

The Zambezi is Africa’s fourth longest river (2574 km – 1599 miles) and flows through Zambia, Angola, Namibia, Zimbabwe, and Mozambique, on its way to the Indian Ocean.

For ease of reference, and also for ecological reasons, the Zambezi is often divided into three sections: The Upper Zambezi, which refers to the stretch of river from the source to the Victoria Falls; the Middle Zambezi, the section from Victoria Falls to the Cahora Dam in Mozambique; and the Lower Zambezi, which is the portion from the Cahora Bassa Dam to the river delta and mouth. (Although the Middle Zambezi was historically considered to begin at Victoria Falls the construction of the Kariba Dam means that, in reality, the Middle Zambezi begins downstream of the impoundment).

Human population density along the banks is low, and most people rely on agriculture and fishing for their livelihoods. Several towns are found along the banks of the Upper Zambezi and, also, the Lower Zambezi, which is the most densely populated section of the river.

Like many rivers in the region, the Zambezi’s flow fluctuates dramatically according to the season and, due to its length, water from the heavy rainfall areas in the catchment areas in Zambia and Angola takes months to reach Zimbabwe and the Victoria Falls.  The summer rains in the catchment usually begin in late November, but the Victoria Falls only experience their peak flow from March to May.

The river’s catchment area covers some 1.3 million square km – and is drained by countless small streams and a number of the large rivers. The Kabompo (rising in Zambia) and the Luena and Kwando Rivers (Angola) flow into the Upper Zambezi and further downstream the Kafue and Luangwa (Zambia), and Shire (Malawi, Tanzania, and Mozambique) are the major tributaries . The Mazowe River (formerly spelt Mazoe), the Sanyati and Shangani are the largest of the Zimbabwean tributaries.

The Zambezi rises in a “dambo” – a form of wetland – in northern Zambia on a watershed that also spawns the upper reaches of the Congo River (Africa’s second-longest river). The Zambezi initially flows north for a short distance before turning south-west into Angola which it traverses for about 240 km (149 miles)  before re-entering Zambia, where it is already about 400 m (1312 feet) wide.

The river soon spreads over the broad, flat Barotse Floodplain which stretches for more than 250 km (155 miles) downstream and is about 50 km (30 miles) wide.  In years of heavy rainfall, shallow water spills across the edge of the floodplain and to the west enters Angola, linking up with flood waters from other rivers and inundating vast areas.

Further south, before the river reaches Zimbabwe, another large floodplain forms at the confluence of the Chobe River and Zambezi.

Floodplains are critically important breeding areas for fish, insects, birds, and a host of other creatures. In river systems where the river flow has not been affected by the building of dams, floodplains also help regulate flooding by dispersing water over wide, often heavily vegetated, areas.

The river enters Zimbabwe about 80 km (50 miles) upstream of the Victoria Falls, and here it is very broad and scattered with small islands. (Victoria Falls N.P. article.) After the falls the river enters the Batoka Gorge, surging its way through 120 km (75 miles) of steep-sided ravines before flowing into Lake Kariba.

The Kariba dam wall was completed in 1959 (see separate article – Lake Kariba) creating one of the largest artificial lakes in the world.

Downstream of the dam the river is known as the Middle Zambezi and broadens to more than 5 km in some areas and is joined by the Kafue, the Mazowe, and the Luangwa Rivers. The areas bordering the middle Zambezi are considered to be some of the best wildlife areas in Africa.

After leaving Zimbabwe the river reaches the Cohara Bassa Dam in Mozambique, and thereafter this segment of the river is known as the Lower Zambezi.  As it makes its way to the sea the river flows through a vast, ecologically important, delta comprising grasslands, palms, swamps, and one of the largest areas of mangrove forest in East Africa.

The delta, which covers about 12 000 sq km (5994 sq m), has suffered considerable environmental harm because the Kariba and Cahora Bassa dams have severely altered the flood regime of the river. Annual floods played a pivotal role in scouring out the delta, opening channels and generally keeping the ecological system functioning, a cycle that no longer occurs with the regularity, or on the scale, that it should.

Most people living along the Lower Zambezi are dependent on agriculture and fishing, activities that are closely linked to the health of the river and delta.

Both dams were built to generate hydroelectricity for the region.

For further information about the Lower Zambezi River and the ecological health of the river delta please read:
Mike Cadman

Mike has worked as a journalist for a variety of international and local media organisations as well as environmental NGO’s for the past 38 years and is the author of five books. During his career, he has covered all major news developments in southern Africa and has travelled extensively throughout many parts of the continent. He spends as much time as possible in the bush and has extensive knowledge of broader environmental issues as well as the creatures that live there.