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Botswana's Okavango Delta is an inland delta whose water never reaches the sea

the gist

The Okavango Delta is a vast inland delta in Botswana, where the Okavango River spreads across the Kalahari Desert basin at about 930 to 1,000 metres above sea level. Each year about 11 cubic kilometres of water flood sandy plains and islands covering 6,000 to 15,000 square kilometres. Much of the water seeps into the shallow aquifer below, and nearly all of it is eventually evaporated or taken up and released by plants. Because the water has nowhere to flow, the delta is one of the few major interior deltas that do not reach a sea or ocean. It became a UNESCO World Heritage Site in 2014 and is home to the Moremi Game Reserve. The delta was once part of Lake Makgadikgadi, an ancient lake that had mostly dried up by the early Holocene.

how it works

The river loses its water as it spreads over flat sand. Much of it sinks into the shallow aquifer, and plants draw the rest up through their roots and release it as vapour, so the water leaves the system through evaporation and transpiration.

so what

The delta is a rare wetland in one of the driest regions on Earth, supporting wildlife that depends on seasonal flooding. It also shows how a river can sustain a huge ecosystem without ever reaching the ocean.

more on this

key facts

Country
Botswana
Located in
Seronga
Area
2.0 million km²

Facts: Wikidata (CC0)

Adapted from Wikipedia, the free encyclopedia · CC BY-SA 4.0

Image: Wikimedia Commons