Okavango Delta is Africa’s “natural oasis” The Okavango Delta or as it is known a the Okavango Grassland, in Botswana, is a very large inland of found where the Okavango River reaches a “tectonic trough” in the central part of the “endorheic” basin of the Kalahari.
All the water reaching the Delta is ultimately evaporated and transpired and does not flow into any sea or ocean. Each year approximately 11 cubic kilometres of water spreads over the 6,000 — 15,000 sq.km. area. Some of the flood water drains into Lake Ngami. The Moremi Game Reserve, a National Park, is on the eastern side of the Delta. This statistical significance helped the Okavango Delta secure a position as one of the “Seven Natural Wonders of Africa, which were officially declared on February 11, 2013 in Arusha, Tanzania and on 22nd June, 2014 the Okavango Delta became the 1000th Site to be officially inscribed on the UNESCO World Heritage List.
The area was once part of Lake Makgadikgadi, an ancient lake that almost dried up by the early Halocene. Although the Okavango Delta is widely believed to be the world’s largest inland delta, it is not. In Africa alone, there are two larger similar geological features —— the SUDD on the Nile in South Sudan, and the INNER NIGER DELTA in Mali.
The Okavango Delta is produced by seasonal flooding. The Okavango River drains the summer rainfall (Jan-Feb) from the Angola Highlands and the surge flows over the 250km by 150km area of the Delta over the next four months (March-June). The high temperature of the Delta causes rapid transpiration and evaporation, resulting in a cycle of rising and falling water level. 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 2mts variation in height all across it.
Of the water that flows into the Delta, approximately 60% is consumed through transpiration by plants, 36% by evaporation, 2% percolates in the “aquifer system” and 2% flows into Lake Ngami. The delta’s profuse greenery is not the result of a wet climate, rather, it is “an oasis in an arid country”.
The Okavango Delta is both a permanent and seasonal home to a variety of wildlife, and thus the Okavango Delta is now a popular tourist attraction. Species include African bush elephant, African buffalo, lechwe, hippos, sitatunga, blue wildebeest, cheetah, hyena, springbok, sable antelope and chacma baboon. The endangered African wild dog still survives within the Okavango Delta, exhibiting one of the richest densities in Africa. The Delta also includes over 400 species of birds like the African fish-eagle, Pel’s fishing-owl, crested crane, lilac-breasted roller, hammerkop, ostrich and sacred ibis. The majority of the estimated 200,000 large mammals, in and around the Delta, are not year-round residents. They leave with the summer rains to find renewed fields of grass to graze on and trees to browse, then make their way back as winter approaches. Large herds of buffalo and elephant total about 30,000 beasts.
The Okavango Delta is home to 71 fish species, including tiger fish, tilapia and various species of catfish. Fish sizes range from 1.4m (African sharp-tooth catfish) to 3.2cms (sickle barb). The same species are to be found in the Zambezi River, indicating a historical link between the two river systems.
The most populous large mammal is the LECHWE ANTELOPE, that are more than 60,000 in number. The LECHWE is a little larger than an Impala with elongated hooves and a water-repellent substance on their legs that enables rapid movement through knee-deep water. They graze on aquatic plants and, like the waterbuck, take to water when threatened by predators. Only the males have horns.
Papyrus and reed rafts make up a large part of the Okavango Delta vegetation. In the Delta, because of the clean waters of the Okavango, there is almost no mud and the river’s load consists almost entirely of sand. The plants capture the sand, acting as the glue and making up for the lack of mud and in the process creating further islands on which more plants can take root.
The Namibian Government has presented plans to build a Hydropower Station in the Zambezi region, which would regulate the Okavango’s flow to some extent. While proponents argue that the effect would be minimal, environmentalists argue that this project could destroy most of the rich animal and plant life in the Okavango Delta. Other threats include human encroachment and regional extraction of water in both Angola and Namibia.