The Land

One of the world's great wetlands

The Okavango Delta lies in the north west of Botswana. Part of the Great East African Rift Valley system, the Okavango Delta is formed as the Okavango River flows into the Kalahari Desert from the Angolan highlands, creating a unique wetland, a huge oasis that sets the region’s rhythm with its annual pulses.

There is less than 2 metres variation in height across the entire 250 kilometre length of the Delta: it is this almost complete absence of topographical relief that leads to the formation of the myriad waterways that make up the Delta. The vast quantities of water flowing into an almost flat desert results in a maze of winding channels, oxbow lakes, islands and floodplains. The water is finally stopped in its lugubrious progress by a fault line. It really is a landscape unlike any other.

Approximately 11 cubic kilometres flow into the Delta each year. The water flows continuously into the Delta and drains the summer (January to February) rainfall from the Angolan highlands. A surge, that flows a staggering 1200 kilometres in a month, occurs in Botswana between March and June. It is during this time that the Okavango Delta is at its largest. The high temperatures in the region cause rapid transpiration and evaporation which results in a cycle of rising and falling water levels.

As one of the only sources of water during the dry period, the Okavango Delta attracts thousands of animals and one of Africa’s greatest concentrations of wildlife. The true miracle of this oasis in the desert is that the flood waters appear just when the rainy season has ended and water and food are becoming scarce in the region. The waters of the annual flood truly are waters of life, resulting in: “… extraordinary juxtaposition of a vibrant wetland in an arid landscape and the miraculous transformation of huge sandy, dry and brown depressions by winter season floods triggers spectacular wildlife displays: large herds of African Elephant, Buffalo, Red Lechwe, Zebra and other large animals splashing, playing, and drinking the clear waters of the Okavango having survived the dry autumn season or their weeks’ long migration across the Kalahari Desert.” (UNESCO)

Once in the Delta, water is lost to transpiration by plants (60%), evaporation (36%), percolation into aquifer system (2%) and finally 2% flows out into Lake Ngami.

The islands of the Delta mostly start as termite mounds (70%) and often have white patches in their centre where the high salt content of the islands collects. This process causes the islands to become toxic and trees die off in the centre. See Formation: The Islands of the Okavango

At the centre of the Delta is Chief’s Island, the largest island in the Delta. Chief’s Island was formed by a fault line which uplifted a 70 x 15 km wide area. Abundant in animal life, it was once reserved as a hunting area for the chief and now forms a safe respite for the resident wildlife when the waters rise.

International Recognition

The ecological importance and 'Outstanding Universal Value' of the Okavango Delta has been recognised by UNESCO and the RAMSAR Convention. The Okavango Delta was designated a Wetland of International Importance in 1996 and a World Heritage Site in 2016.

Together these international bodies aim to protect the future of this unique and sensitive eco-system.

Ramsar Site

The Okavango Delta is the largest Ramsar Site in the world. The Ramsar Convention on Wetlands is an international treaty for the conservation and sustainable use of wetlands.

The Okavango Delta was designated as Botswana’s first Wetland of International Importance in 1996 in recognition of its unique hydrological qualities. A number of criteria were noted during the review, including:

  •  It is a unique inland wetland complex which supports 20 IUCN Red-Listed plant species of which seven are at very high to extremely high risk of extinction.
  •  The Site hosts numerous critically endangered species as well as others such as red lechwe, hippopotamus, leopard and sitatunga
  • More than 50% of its plant species are endemic, and it maintains terrestrial species that are absent from the surrounding savannah habitat as they require the prevailing conditions of humidity or soil moisture.
  • During the migration cycle the site is an important refuge for several species, including elephant, zebra and wildebeest, and it forms the most important breeding site for the slaty egret.
  • The Delta routinely attracts more than 20,000 waterbirds and supports more than 1% of the biogeographic population of 13 bird species including the great white pelican, squacco heron, saddle-billed stork, fulvous whistling duck, African pygmy goose and the blackwinged pratincole.

The Ramsar Site covers 5,537,400 hectares. and extends 90km beyond the World Heritage property boundary in the north and south-east. The northern boundary of the Ramsar Site follows the Kwando River which forms the border between Namibia and Botswana. The World Heritage property covers a smaller area of 2,023,590 hectares which is surrounded by a buffer zone of 2,286,630 hectares.

The Okavango Delta is the largest inland delta in sub-saharan Africa after the inner delta of the Niger. It lies in a semi-arid area and every year 97% of the annual inflow of between 7,000 and 15,000 million cubic meters is lost to evapotranspiration and seepage. Only 3% of the water is discharged from the delta.

World Heritage Site

Adopted by UNESCO in 1972 the Convention concerning the Protection of the World Cultural and Natural Heritage seeks to encourage the identification, protection and preservation of cultural and natural heritage around the world considered to be of outstanding value to humanity.

One of the most iconic natural areas on the planet, The Okavango Delta was listed as the 1000th World Heritage Site last Sunday at the 38th session of the World Heritage Committee in Doha, Qatar. Joining Ngamiland’s Tsodilo Hills on the World Heritage List, the Okavango Delta was recommended by IUCN, UNESCO’s advisory body on nature.

“The Okavango Delta has long been considered one of the biggest gaps on the World Heritage list and IUCN is proud to have been able to provide support to this nomination,”

Julia Marton-Lefèvre, IUCN Director General

Sustaining populations of some of the planet’s most threatened mammals such as the cheetah, rhinoceros, the wild dog and the lion. The Okavango Delta is also home to 24 species of globally-threatened birds and is key to the survival of Botswana’s 207 000 elephants.

“The Okavango Delta has been a conservation priority for more than 30 years and we are delighted that it has finally gained the prestigious status it deserves”

Threats to the Okavango Delta

The future of the Okavango Delta depends on her people

Because the Okavango River rises in the Angolan highlands and flows over 1,000 miles, passing through Namibia, before entering Botswana and forming the Okavango Delta there exist many threats to the Okavango Delta’s existence.

As Angola develops through substantial oil revenue and the threat of violence in that country diminishes there will be more pressure on the water that makes up the Okavango Delta at source as human populations increase and increased agricultural development places pressure on the resource.

Namibia through which the Okavango River flows as the Kavango River is also considering extracting water upstream of the Delta to use for power generation, agriculture and to supply their capital Windhoek.

In 1994 the three basin states formed the Permanent Okavango River Basin Commission (OKACOM), to of promoting sustainable management of the river basin through the development and implementation of a comprehensive basin–wide management plan.

Within Botswana, the threat comes from human habitation near the Delta and the effect this has on the animal numbers that sustain the ecosystem.

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