| Designations | |
|---|---|
| Official name | Zambezi Floodplains |
| Designated | 2 February 2007 |
| Reference no. | 1662[1] |
TheBarotse Floodplain, also known as theBulozi Plain,Lyondo,Ngulu, or theZambezi Floodplain, is one of Africa's greatwetlands, on theZambezi River in theWestern Province ofZambia. It is a designatedRamsar site, regarded as being of high conservation value.[3]
The name recognises thefloodplain as spawning the culture and way of life of theLozi people, "Rotse" being a variant ofLozi, and "Ba" meaning "people". They became a powerful kingdom inCentral/Southern Africa under their king orlitungaLewanika, whose realm extended up to 300 km from the plain and was calledBarotseland.
The region is a flatplateau at an elevation of about 1000 m, tilting very slightly to the south. The Zambezi and itsheadwaters rise on the higher ground to the north, which enjoys good rainfall (1400 mm annually) in arainy season from October to May. A flood moves down the river, reaching a flat region formed fromKalahari sands, about five hundred kilometres across. To the south, around theNgonye Falls, harder rock is found at the surface and has resisted the river's tendency to cut a channel down into it, and so acts a bit like a dam. Behind it, the floodplain has formed. Below the falls, the river flows nearly twice as fast as it does on the plain and flows more swiftly in a narrower valley less prone to flooding.
The floodplain stretches from the Zambezi'sconfluence with theKabompo andLungwebungu Rivers in the north, to a point about 230 km south, above the Ngonye falls and south ofSenanga. Along most of its length its width is over 30 km, reaching 50 km at the widest, just north ofMongu, principal town of the plain, situated at its edge. The main body of the plain covers about 5500 km2,[4]but the maximum flooded area is 10 750 km2 when the floodplains of several tributaries are taken into account,[5] such as theLuena Flats. The Barotse Floodplain is the second largest wetland in Zambia after theLake Bangweulu system, which differs in having a large permanent lake and swamps, and a much smaller area which dries out annually.[4]
The satellite photo was taken in April 2004 at the peak of the flood, Note that the northern part of the plain, near Lukulu, is less flooded, the land there varies a bit more in height and the water tends to keep to the many river channels.
The peak of theflood occurs on the floodplain about 3 months after the peak of the rainy season in January–February. The flood usually peaks in April, and recedes in May to July, when grasses quickly grow on the exposed plain. At the river's lowest water in November the floodplain still contains about 537 km2 oflagoons,swamps and channels.[5] The flood leaves behind a fertile grey to black soil overlaying the Kalahari sands, enriched bysilt deposited by the flood as well ashumus from vegetation killed by the initial flood, and from decaying aquatic plants left to dry out in the mud. It provides a good soil, but in the late dry season it bakes hard in the heat of the sun.[4]
As the floods recede, water is left behind in lagoons, swamps, andoxbow lakes.
The floodplain is in theZambezian flooded grasslandsecoregion, and is bordered by slightly higher sandy ground on which grow dry grasslands (Western Zambezian grasslands) with woodland savanna (Zambezian Baikiaea woodlands) to the east and south, and patches of evergreen forest (Cryptosepalum dry forests) in the north and east.
The flood providesaquatic habitats for fish such astigerfish andbream,crocodiles,hippopotamus, waterbirds, fish-eating birds, andlechwe, the wadingantelope. After the flood, the plain is a habitat for grazing animals such aswildebeest,zebra,tsessebe and small antelope suchoribi andsteenbok, and their predators.[4]These herbivores have been displaced in most areas by the cattle grazed by the Lozi, but they have provided a large game reserve on the dry grassland to the west, theLiuwa Plain National Park, once the Litunga's hunting grounds, established as a game reserve byLewanika in the 19th century. In addition the entire western of the Zambezi within the country is a Game Management Area.
About 250,000 people live on the plain with a similar number of cattle,migrating to grasslands at the edge of the floodplain when the flood arrives. The floodplain is one of the most productive areas for raising cattle in the country.[4]
The Lozi also catch fish, eating about five times as much as the national average. At the height of the flood they usefish traps and spears for fishing, and they usegill nets in the lagoons left behind by the falling flood. Fishspawn just before the flood, the first floodwaters are naturallyhypoxic (low in oxygen) which kills most fish, while eggs survive.[4]
The Lozi cultivate crops on the floodplain such asmaize,rice,sweet potato, andsugar cane.
November to January are lean months.[4]Stored produce from the previous growing season is almost used up and in any case would need to be transported during the migration, while the new season's crops and grasses are not yet productive, and at the same time fishing stops for the spawning season. Hunting and trapping animals, which might have filled the gap, is no longer available to most people, and trapping waterbirds is one of the few alternatives to buying flour.
The floodplain determines and dominates the way of life, economy, society and culture of the Lozi, who are skilled boat-builders, paddlers and swimmers.[4]The annual migration with the flood is celebrated in theKuomboka ceremony held at Mongu, capital of Barotseland and its successor, the Western Province.
In the occasional very wet year such as 2005, lives and property are lost in floods on the Barotse Plain. More often, however, it is a very good example of the principle that natural annual flooding by rivers is valuable and productive for wildlife and human populations, while damming rivers to control floods, as has happened with theKafue Flats, is potentially damaging to the environment.
Development on the plain has been restricted until now to—
Tight control over access to the floodplain by the Litunga and the homogeneity of the indigenous people have slowed commercial development by outsiders.
A new project, theMongu-Kalabo road, will have more far-reaching consequences. Around 2002 construction started of a 46-kilometrecauseway across the centre of the floodplain to take a paved highway fromMongu toKalabo, via the ferry across the main river channel at Sandaula, which would then be replaced by a 500-metre bridge. It is treated as an extension of theLusaka-Mongu Road fromLusaka. Originally intended to be completed in 2006, it has been delayed by the difficulty of building on the floodplain. There is no rock in the region, and the causeway has been built from sand and gravel scooped out from shallow depressions next to it. Higher than usual floods washed away large sections. The contractor was aKuwait-based company which acknowledged that conditions were difficult.[6] TheTimes of Zambia reported that the company underestimated the floodplain environment, and abandoned the contract.[7] Subsequent modifications have been made to raise the road height and to increase the number and size ofculverts, and this in turn led to funding problems. The road has been completed in 2016. A Chinese contractor, theAviation Industry Corporation of China (AVIC International), finished the 286.9 million US dollars project. The road stretches 34 Kilometres in the Baroste plains with 26 bridges across it.[8][9]
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