The Okavango Delta explained
Bechuanaland was a British protectorate until 1966 when Botswana was created as a newly-independent nation state. Fledgling Botswana promptly discovered three of the world’s richest diamond mines and has never looked back. Coincidence, of course! It remains one of Africa’s real success stories: politically stable; sound economy; healthy wildlife conservation policies.
The majority of Botswana is dry, sandy, scrub-desert, known as sandveld, but in the north-west corner is the phenomenon known as the “Okavango Delta”. Imagine an arm outstretched with the fingers splayed; this represents the Okavango River as it flows through the panhandle and forms the inland delta, represented by the splayed fingers. The arm and fingers are always there, but there is an annual flood which fills the spaces between the fingers leaving just two principal land masses, The Moremi Tongue and Chief’s Island (plus a scattering of smaller islets). Immediately to the north of the delta is a large area of land divided into “concessions”: a concession is land that is leased to a private individual who can use it, in effect, as a private national park. The area between national parks and the adjoining concession land is not fenced. Added to this is a confusing array of game reserves, forest reserves, flood plain reserves, community concessions, community trusts, game management areas and a variety of other tracts of land. The subtle differences between one name and another are lost on me: the result on-the-ground is that a national park, as far as the animals are concerned, is enlarged. I guess it boils down to who ultimately gains an income from the land, but wildlife freely crosses from one piece of land to another. The KAZA initiative seeks to enhance this notion (see below).
When on safari, concession land has a couple of subtle advantages: as it is private land, you are allowed to drive at night, and allowed to drive off road, two things that national parks don’t allow. Conservation-wise, driving off road does little harm, so long as traffic density is low. Traffic density is low in concession areas because the concession license permits a finite number of lodges of a finite capacity (usually 8 or 10 rooms) whereas lodges in national parks tend to be larger and more numerous.
The Okavango Delta area consists of dozens of rivers and waterway: some flow permanently, others are seasonal. There are two main rivers to understand: they are very different in character and their fates are very different. The Okavango and Kwando rivers: both rise in the highlands of Angola and flow in a south-easterly direction, away from the Atlantic which is the nearest ocean to their sources. The Okavango forms the delta and the water either evaporates or soaks away into the ground.
The Kwando follows a parallel course to the Okavango, immediately to the north. Loosely speaking it forms the boundary of the concession lands north of the delta. It forms the Savuti swamp, north of the delta, and when it flows out of the swamp, now travelling north-east, it changes its name to the Linyanti River. The Linyanti then morphs into the Chobe River which joins the Zambezi at the town of Kazungula. The Zambezi flows over Victoria Falls and then makes its passage all the way (1,580 Km) to the Indian Ocean.
The Seasons of The Delta
The Okavango receives water from two different sources at two different times of the year. The first is the annual flood: rainwater in the Angolan highlands falls in December and slowly makes its way down to the Delta a couple of months later, creating a slow-motion flood-tide which gradually fills the Delta. As the flood travels down the Panhandle, it overflows its banks revitalizing the swamps and covering the sandbanks. On reaching the fan-shaped Delta, it spreads out overflowing river channels and raising the water level in lagoons and backwaters. Plants in and around these seasonal swamps thrive once again. The flood’s front moves slowly, travelling at speeds of only one kilometre per day (it takes 4 months for the flood to travel the 250km from Mohembo in northern Botswana to Maun). This is due to both the very shallow gradient (only a 65m fall over 250 Km) and because the water is impeded by vegetation. Thus, the floodwater reaches much of the southern half of the Delta in the middle of the “dry” season, June and July.
As the floods subside and the water levels recede, the hot onset of Spring and summer peak with the very hot and dry month of October when dust and airborne sand particles create spectacular sunsets.
The second rush of water comes with the local seasonal rains that fall over the Delta in the months between December and March. These rains are not like the monsoons of Asia, but rather localized thunderstorms that are usually brief but potent and it’s unusual for there to be rain on consecutive days. The rains usually abate with the onset of April and dry up quickly leaving behind a lush, green carpet of grasses and reinvigorated plant life.
The Okavango is constantly changing as the water moves through the channels and erodes new channels. The amount of water and when it arrives is dependent on the amount of rainfall in Angola which fluctuates from year-to-year.
The Delta’s Water
Approximately 2% of the floodwater reaches Maun in a good year. About 95% escapes into the air via evaporation and transpiration and a small fraction seeps into the underlying groundwater. Because most of the Delta’s water is lost to evaporation, salts and minerals from the Okavango River are deposited in the Delta.
The Okavango’s water is lowest from November to January when floodwater is confined to the permanent swamps, an area of 4,000 km². Flood levels in the Delta are highest between March and September, depending on where one measures. At peak flood, an additional 4,000 to 5,000 km² of seasonal swamps and floodplains are created.
The water of the Okavango is clean and pure and it is even safe to drink straight from the flowing channels. The water tends to be stained the colour of weak tea by plant tannins, but this does not affect the purity. The taste of the water may also seem strange due to the presence of mineral salts, but again, this does not pose any health hazards. There is no industry in the northern Delta and no agriculture to speak of, so the water coming in is untainted and natural. Additionally, the waterways of the Delta are generally shallow so that sunlight penetration is good, presenting very poor conditions for micro-organisms and bacteria to flourish. Finally, the water is continually refreshed through the seasonal cycles and as it flows into the sandy channels, it’s finely filtered as it passes through hundreds of kilometres of papyrus beds and sandbanks.
The Topography of the Delta
Apart from the permanent channels, the Delta is covered by shallow water, flooded grasslands, backwater swamps, ox-bow lakes and hidden lagoons, mostly interconnected by narrow waterways. The region is a complex of perennial and seasonal swamps and floodplain grasslands. The seasonal swamps are only flooded during high water, when the rivers spill their banks and inundate vast tracts of land. The floodplains are only intermittently covered, depending on rainfall or the direction and intensity of the river’s flow that year. Change is the essence of the Okavango’s waterways.
Scattered throughout the Okavango Delta are thousands of islets. Together, they constitute an area equal to that covered by the Delta’s water (approx 5,000 Km²) and they come in all shapes and sizes, rising just high enough above the surrounding reed-beds and floodplains to support trees. Ensured of a regular water supply, the woodlands that fringe the islands grow lofty and luxuriant with species that could otherwise never survive on the impoverished Kalahari sands.
There are an estimated 50,000 islands scattered throughout the Delta in a dazzling array of forms. In the northern permanent swamps there are hillocks so small that there is only room for a single grove of the graceful Date palm, Phoenix Reclinata. In the seasonal swamps of the middle Delta the islets become larger, their perimeters edged by a narrow band of woodland comprising an assortment of trees such as Jackalberry, Mangosteen, Knobthorn, and Sycamore Fig.
Each island is unique in the mix of trees it supports. The islands are formed in a variety of ways, most developing from small nuclei. Some begin as an elevated feature such as a termite mound or as abandoned channel beds that remain after the water course has been blocked by vegetation (mostly papyrus) and switches to a new channel. Their original shape is usually etched in their eventual form, so islands that started as termite mounds are typically round, while those that begin as former channel beds tend to be long and sinuous. Other islands, for example the massive Chief’s Island, are the result of tectonic activity.
Towards the southern end of the Delta, the islands are quite different. Sometimes called “sandveld tongues” which are areas of Kalahari sand that penetrate deep into the Delta, reminders of the more arid origins of this oasis. The largest, The Moremi Tongue, covers more than 1,000 Km² in the east of the Delta and supports vegetation and animal life more typical of the dry deciduous Kalahari woodlands to the east and north. All the larger islands are fringed by a wide margin of grassland floodplain which is inundated each year only to reappear green and replenished once the waters have passed through.
Most of the smaller islands owe their existence to those ancient builders, the fungus-growing termites. Their activity not only raises patches of land above the general flatness of the Kalahari, but their earth-moving endeavours enrich the soil, which in turn promotes the growth of trees. The termite islands, or ‘Termitaria’, also play an important role in the Delta’s pattern of water flow, particularly in the seasonal swamps. Termitaria are often built in the narrow entrances to floodplains: as they grow, their bases join together so that the land rises and prevents the flow of water into the formerly flooded area. With time, the dried floodplains are colonized by trees. If several islands develop close to one another, the continued activity of the termites will cause them to join and a larger island will be formed. In this way, the lands of the Delta and its waterways are constantly changing.
Quite simply: Linyanti is Africa’s best-kept secret.
The Linyanti area consists of private concession land immediately north of Moremi NP and the Okavango Delta; west of Chobe NP; south of the Caprivi Strip. It consists of three tracts, East Linyanti, Kwando and Selinda and if you tot-up the total number of lodge beds available in this massive area, it comes to just over 100! The chances of seeing anyone else while out and about are virtually nil: if you like your Africa pure, pristine and wild, look no further.
Linyanti is also famous for a winning combination of top-end guides, outstanding lodges, staggering elephant numbers and predator action to satisfy even the most demanding observer (lions, hunting dogs and leopard in particular).
During a stay in Linyanti you will hear talk of the Savute Chanel and Selinda spillway.
The Savute Channel
The Savute channel is unusual because it has a mind of its own: it flows and dries up independently of the local rains. It may flow for many years and then suddenly dry up for over 80 years (witness the avenue of dead trees that stands along its banks) before flowing again. When the channel flows, it is a major water source for animals during the dry winter months.
The channel flows from the Linyanti/Kwando River east into the Savute marsh. When it dries up, the landscape dries too and the wildlife of the region turns to the few man-made waterholes that have been dug. When it does flow it is a lush larder, 100 Km long. It flowed in 2010 and 2011 when the flood was particularly high.
The Selinda Spillway
This is a channel that links the Kwando River to the Okavango floodplain. There is a popular myth that the channel may flow in either direction, depending on the relative water levels in each of the two rivers. That is not the case. The flow is eastwards from the Okavango into the Linyanti River.
In 2012 both the Savute Channel and the Selinda spillway flowed.
Kavango-Zambezi Transfrontier Park is a giant idea that will create a giant National Park across five countries: the biggest in the world at 280,000 Km².
In December 2006 a Memorandum of Understanding was signed to unite 14 national parks, ranging from Angola, through the Okavango Delta in Botswana, the Caprivi Strip in Namibia, Victoria Falls in Zambia and Hwange NP in Zimbabwe to create a world without borders where wildlife can roam freely and where safari travellers can journey without restriction.
Some of the National Park’s involved are:
Chobe NP, Botswana
Kalahari salt pans, Botswana
Sioma Ngwezi and Kafue NP’s, Zambia
Victoria Falls, Zim-Zam border (which would be the new hub)
Hwange NP, Zimbabwe
Lake Kariba, Zimbabwe and Zambia
The participating countries
The biodiversity of KAZA is as phenomenal as the project itself and includes savannah, myombo and mopane woodlands, desert and wetlands. The park will contain approx 3,000 species of plant life (of which some 100 are endemic) and more than 500 species of birds. The resident wildlife includes Africa’s largest elephant herds, buffalo, hippopotamus, lion, lechwe, roan, sable, eland, zebra, wildebeest, waterbuck, puku, bushbuck, sitatunga, wild dogs, spotted hyena and a host of other mammals.
Human origins date back more than 80,000 years with the advent of bushmen. More recently (1750’s) Abantu settlers moved into this area living in family groups called Khoi-Khoi. Today you find groups of Bushmen living as hunter-gatherers amongst the Abantu tribes harmoniously.
© With thanks to Wilderness safaris for the pics.