The Okavango Delta
The Moremi Reserve includes the eastern ends of the Moanachira Channel and almost all of the Khwai River, which ends its course in the sands of the Kalahari a few kilometres from the Moremi border. This intrusion of water into the otherwise barren Kalahari sands results in an ecological richness and diversity that is rare in nature.
The Channel and the Thaoge Plains in the northwest is where we realize our adventures in Mokoro (dugout canoe). In the Moremi Game Reserve we explore the eastern islands of the Okavango Delta by safari vehicle in search of the wildlife that abounds in this natural paradise of plains and riverine forests.
The channel and plains of the Thaoge represent the Okavango Delta as we imagine it, endless lagoons covered with water lilies and lined with small islands of lush palm trees. Here, we are looking for an island to set up our camp to explore the surroundings on foot, watch the sunset over a lagoon from our mokoros, listen to our Bayei Mokoro boatmen singing in the African night.
The Okavango Delta is probably one of the most enchanting places in Africa. A whirlwind of opulence in a Kalahari sand desert, the delta is a remarkable phenomenon. It owes its origins to the formation of the Rift Valley along the course of the Okavango River. The region was formed over the last 5 million years as a result of atmospheric changes and movements of the earth’s crust.
About 5 million years ago, a relatively recent event (geologically speaking) made the southern hemisphere’s atmosphere increasingly dry due to glaciation in Antarctica, which absorbed most of the atmospheric moisture. Three million years ago, strong easterly winds led to the formation of elongated dunes that cross the middle Kalahari from east to west. When wetter weather returned, these dunes channelled river flow in one direction only, towards Lake Makgadikgadi. The wetter weather also caused the large rivers of the Middle Kalahari, namely the Okavango, Chobe and Zambezi Rivers, to flow. They all flowed eastwards, together with the Limpopo River, into the Indian Ocean.
Then, about 2 million years ago, a geological upheaval in the Earth’s crust caused a fault that changed the course of these great rivers. This fault, known as the Kalahari-Zimbabwe axis, starts at Harare via Bulawayo and ends east of the Kalahari. The rivers then flowed into the large basin that had formed, creating one of the largest lakes in Africa, Lake Makgadikgadi.
Eventually, the lake was saturated and the water had to find a way to access the ocean. So about 20,000 years ago, the waters of this great lake were forced north and then east. This caused the connection between the middle and lower Zambezi, resulting in the appearance of Victoria Falls. As water could now flow out of the lake, a partial draining of the lake occurred. A drier climatic period followed, resulting in increased evaporation and reduced river flow. About 10,000 years ago, the drying of Lake Makgadikgadi was in an advanced stage. Wind-blown sand, along with the numerous sediments and debris deposited by the Okavango, gradually filled the lake.
The formation of the Gumare Fault led to a reduction in the elevation of the land, causing the waters of the Okavango to spread over a much larger area, forming the now characteristic fan-shaped Inner Okavango Delta. Today, the only remains of the former Makgadikgadi Lake (with the exception of the Okavango Delta) are Nxai Pan, Lake Ngami, Lake Xau, the Mababe Depression and the two main basins of Makgadikgadi (the Sua and Ntwetwe sections).
One of the characteristics of the delta is its annual flooding. The Okavango, which originates in Angola on the Benguela Plateau, flows through the Caprivi Strip in Namibia in a southeasterly direction, crosses the rapids at Popa Falls and enters Botswana at Mohembo. This results in heavy rainfall from Angola to Botswana (about 11 billion cubic metres of water per year). The swollen river overruns the low banks, and the annual flooding of its floodplains begins. No two floods are ever the same, but it can be said that the permanent delta covers an area of 16,000 km2, while a large flood can cover up to 18,000 km2 depending on the season. It can take 6 months to go from Mohembo to Maun, through the maze of canals and lagoons.
More than 95% of the Okavango’s water evaporates before reaching the Thamalakane River near Maun. The Thamalakane River drains the area and carries the rest of the water to the Boteti River, which flows through a break in the fault to Lake Xau and eventually to parts of Makgadikgadi. This water outlet is one of the reasons why the water in the delta is fresh as it carries salts. The flooding of the Okavango is not a violent process. The water flows gently into the canals and plains. The total height from one end of the delta to the other is only 62 metres over a distance of about 250 kilometres. The slow movement of the water means a low sediment load and therefore explains the incredible clarity and purity of the water of the Okavango, for which it is renowned.
In the late 1800s, an epidemic of rinderpest spread across the continent, destroying much of Africa’s wildlife and livestock. As wildlife is home to tsetse flies, this led to a natural decline in the tsetse fly population in the region. For this reason, it became possible to move livestock in and through the region without fear of disease. The Batawana tribe feared that the constant competition between returning game and cattle herds for grazing, as well as uncontrolled hunting, would lead to habitat destruction and a decrease in game populations.
During this period (late 1950s, early 1960s), the tribe was ruled by Mrs. Moremi, widow of Chief Moremi III, whose son, Matiba, was too young to govern. Thus, the Moremi Reserve was officially proclaimed on March 15, 1963.
The Moremi Reserve is now administered by the Department of Wildlife and National Parks; it is a rich and fascinating area. The Moremi Game Reserve is a complex part of the Okavango Delta, including permanently flooded areas, seasonally flooded areas and drylands.
Located in the north-eastern part of the delta, it is probably Botswana’s premier tourist destination, as it encompasses several different types of ecological zones. The total area of the reserve is 4,871 square kilometres. This represents almost a third of the Okavango Delta, something Botswana can be very proud of. The drylands of Moremi consist mainly of mopane velds (Colophospermum mopane). The giant mopanes form a forest canopy and give a unique atmosphere to this region.
Other main vegetation types are riverine forests, floodplain grasslands, marginal forests on the edge of floodplains, sand velds of Terminalia sericea, sand velds of Acacia erioloba and island communities of Hyphaene petersiana.
In the 1930s Botswana was still a British protectorate called Bechuanaland. At that time, very few people visited the banks of the Chobe River, and the area was mainly used for hunting and lumbering. The large population of elephants attracted many hunters to the area at a time when the ivory trade was widespread and conservation of wildlife and the environment was not a top priority. Colonel Charles Rey, then Commissioner of Botswana, wanted to declare the area as a reserve. However, his dream did not come true until the early 1960s, when Chobe National Park came into being under Bechuanaland Government Proclamation No. 22 of 1961.
After entering Botswana, the Kwando River became the Linyanthi. In Parakurungu, it becomes the Itenge and it is only near the Ngoma Gate that it becomes the Chobe River. From the point where the Chobe bends sharply, the Magwegqana or Selinda spillway connects the Delta to the Chobe. It is commonly accepted that the Selinda can flow in both directions, so the Chobe does the same. This is not true. In reality, the water only rises a small distance, creating the impression of a change in the current.
The Savuti region consists mainly of Camelthorn sand velds (Acacia erioloba), silver Terminalia sand velds (Terminalia sericea), scrubby savannah and mopane veld. Savuti’s almost desert landscape with its scorching sun, warm, loose sand, animals escaping the heat by clustering in the small areas of shade available, and elephants eagerly queuing to reach the increasingly limited water supply, offer a very different wildlife experience, yet so authentic to Africa.
There is still speculation about how this once massive lake received its waters. The most popular explanation is that one day the Upper Zambezi River, the Chobe and Okavango Rivers flowed together, through northern Botswana and into the sea via the Limpopo. A slight deformation of the earth’s crust blocked this flow to create a vast lake. Over time, however, further crustal movement caused these rivers to find a new route to the sea. The direction of these rivers changed with the faults; the Upper Zambezi and Chobe turned northeast and, after plunging through Victoria Falls, joined what is now the Middle Zambezi.
Trapped by an emerging rift valley, the Okavango seeped through the vast sand accumulations to create the delta we see today. Condemned by a climate change that has reduced rainfall and brought back almost desert conditions, the superlake, cut off from its water supply, has dried up and no longer exists.
The Savuti Canal
One of the great mysteries and charms of Savuti lies in its famous canal. It runs 100 kilometres from the Chobe River, through a breach in the sand ridge, to the Mababe Depression. Falling only about 18 metres (about 18 centimetres for every kilometre travelled), this canal carries water from the Chobe to Mababe, creating a small pond where it enters the Depression.
It is the canal and its water that explains the fantastic abundance of game that can sometimes be seen in Savuti. However, the canal doesn’t always flow, and this is where its great mystery lies.
Reports by early explorers confirm that the canal flowed in the 1850s and up to about 1880. At that point, it stopped flowing and remained dry until the mid-1950s and then, without explanation, it began to flow again. Since then, it has been “on” and “off” several times. It is currently dry. It is this chimeric flow that explains the dead trees you will see in the canal.
The long dry period of this century has given the Camelthorns (Acacia erioloba) enough time to establish and develop fully. The flood that followed drowned the trees in the channel and at the edge of the pond. The dead trees, which remained standing for more than 35 years, are today one of the most important elements of the Savuti landscape.
One possible explanation for the irregular flow of the Savuti Canal lies in tectonic movements (movements of the earth’s crust). Even without the water of the Chobe, Savuti remains a place of enchantment, of singular beauty, and has one of the largest populations
The sides of the Savuti
The area consists of the Sua and Ntwetwe sections. During the heat of late winter, the slopes become a shimmering mirage of ethereal and disorienting austerity. The large number of small villages and the small tools and other Stone Age artifacts that can be found scattered around the islands (e.g. on Kubu Island) show that the Makgadikgadi Pangs were home to human habitation and livestock long ago. At one time, the Makgadikgadi Gangs were an important trade route.