Okavango Delta

The Okavango Delta is spread over an area of some 15000 km² of wetland, with a particularly broad diversity of fauna and flora. Described as "the jewel" of the Kalahari, the Delta is a tranquil and isolated oasis set in Botswana's harsh and arid desert.

The source of the Okavango Delta
Spurred by huge subtropical storms, the Cubango River rises in central Angola, flows through Namibia as the Kuvango River and finally enters Botswana as the Okavango River at Mohembo in the north. With it comes some 11 billion cubic metres of water each year which drains away through a maze of lagoons, channels and islands before disappearing into the Kalahari wastes of the south.

The Okavango River is funneled through parallel faults of the Panhandle as a deep and fast-flowing river before being confronted by another perpendicular fault, that introduces a sudden increase in gradient. This slows the flow of water considerably, and it spreads into relatively shallow sediment, with a fall of only 62 metres over approximately the next 250 kilometres.

The Okavango's seasonal floods
An important feature of the Okavango is the seasonal flooding which commences around January/February in the north and ends about six months later in the south. This results in a cyclical motion of water rising in the north as it recedes in the south during summer, and a rising in the south as it drops in the north during winter. The nature of the annual floods is gentle with floodplains and islands disappearing under water and then reappearing in an ever-changing landscape at the end of each season - this is particularly pronounced in the central Okavango.

The flood zones
The Delta can be reasonably well divided between a permanently flooded zone in the north and a seasonally flooded zone in the south. The northern zone includes the panhandle with its riverine forest fringes immediately adjacent to arid Kalahari woodlands, and depending upon the inflow from Angola, a vast wetland of up to 12000 square kilometres of islands, reed beds, channels, forest banks and permanent water ways. The seasonally flooded zone has large Kalahari sandveld islands with dry and deciduous woodlands fringed by wide grassy floodplains that are heavily influenced by the seasonal floods.

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