Okavango Delta

The Okavango Delta or Okavango Grassland is a vast inland delta in Botswana formed where the Okavango River reaches a tectonic trough at an elevation of in the central part of the endorheic basin of the Kalahari Desert.

It is a UNESCO World Heritage Site as one of the few interior delta systems that do not flow into a sea or ocean, with a wetland system that is largely intact. All the water reaching the delta is ultimately evaporated and transpired. Each year, about of water spreads over the area. Some flood waters drain into Lake Ngami. The area was once part of Lake Makgadikgadi, an ancient lake that had mostly dried up by the early Holocene.

The Moremi Game Reserve is on the eastern side of the delta. The delta was named one of the Seven Natural Wonders of Africa, which were officially declared on 11 February 2013 in Arusha, Tanzania. On 22 June 2014, the Okavango Delta became the 1000th site to be officially inscribed on the UNESCO World Heritage List.

Geography

Floods

The Okavango is produced by seasonal flooding. The Okavango River drains the summer (January–February) rainfall from the Angola highlands and the surge flows in around one month. The waters then spread over the area of the delta over the next four months (March–June).

The high temperature of the delta causes rapid transpiration and evaporation, resulting in three cycles of rising and falling water levels that were not fully understood until the early 20th century. The flood peaks between June and August, during Botswana's dry winter months, when the delta swells to three times its permanent size, attracting animals from kilometres around and creating one of Africa’s greatest concentrations of wildlife.

The delta is very flat, with less than variation in height across its , while the water drops about 60 m from Mohembo to Maun.

Water flow

Lagoons

When the water levels gradually recede, water remains in major canals and river beds, in waterholes and in a number of larger lagoons, which then attract increasing numbers of animals. Photo-safari camps and lodges are found near some of these lagoons. Among the larger lagoons are:
*Dombo Hippo Pool ()
*Gcodikwe Lagoon ()
*Guma Lagoon ()
*Jerejere Lagoon/Hippo Pool ()
*Moanachira Lagoon/Sausage Island ()
*Moanachira Lagoon ()
*Shinde Lagoon ()
*Xakanaxa Lagoon ()
*Xhamu Lagoon ()
*Xhobega Lagoon ()
*Xugana Lagoon ()
*Zibadiania Lagoon ()

Salt islands

The agglomeration of salt around plant roots leads to barren white patches in the centre of many of the thousands of islands, which have become too salty to support plants, aside from the odd salt-resistant palm tree. Trees and grasses grow in the sand around the edges of the islands that have not become too salty yet.

About 70% of the islands began as termite mounds (often '' Macrotermes'' spp.), where a tree then takes root on the mound of soil.

Chief's Island

Chief's Island (), the largest island in the delta, was formed by a fault line which uplifted an area over and . Historically, it was reserved as an exclusive hunting area for the chief, but is now a protected area for wildlife. It now provides the core area for much of the resident wildlife when the waters rise.

Climate

The Delta's profuse greenery is not the result of a wet climate; rather, it is an oasis

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