A rapid biological assessment of the aquatic ecosystems of the Okavango Delta, Botswana: High Water Survey

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The Okavango Delta is one of southern Africa's largest wetlands. It is situated in the semi-arid Kalahari of north-western Botswana, where rainfall is seasonal and in the region of 500 mm per year. Being a semi-arid subtropical environment, potential evaporation is 5-6 times that of rainfall. The main source of water for the Okavango Delta is the Okavango River, which has a mean annual discharge of approximately 9.86 x 109 m3, with peak flows in March and April and low flows in October and November. However, the flood waters from the Okavango River take many months to reach the seasonal swamps such that the maximum extent of flooding in the Delta is in the dry season (August to September). Given large differences in water supply and demand, the Okavango wetland fluctuates in area from 6,000-8,000 km2 during the non-flood season to over 15,000 km2 during the flood season. The Okavango River arises from a series of headwater streams on the southern slopes of the Angolan highlands, forms the boundary between Angola and Namibia for hundreds of kilometers, and then crosses the Caprivi Strip in Namibia before entering Botswana as a single broad river. As such the drainage basin of the Okavango River is shared by three countries. Upon entering Botswana, the Okavango River is approximately 200 m wide and 4 m deep. In its upper reaches in Botswana, the Okavango River is confined within a depression known as the Panhandle, where it meanders within a broad floodplain before water spreads out over the surface of the large alluvial fan that is known as the Okavango Delta.

Washington D.C.
Alonso LE, Nordin L
Conservation International
Series Editor:
Alonso, L.E.; Nordin
Series Title:
RAP Bulletin of Biological Assessment
Item Type:
Attachment Size
RAP-Botswana.pdf 4.85 MB

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