By Peter Comley
From the current issue of the Zambezi Traveller available in print and online.
We take a look at how nature has contrived to bring water to one of the great wildlife areas of the world.
Elephants from the air (Image credit: African Bush Camps)
Janis Joplin may have put it more crudely, but when it comes to the rivers of northern Botswana “it’s all the same thing, man.” The Cuando, which rises on the slopes of Mount Tembo, flows out of Angola, across the Caprivi Strip and then, renamed as the Kwando, forms the border between Namibia and Botswana, before it abruptly becomes known as the Linyanti. Its languid course through papyrus-edged pools alters suddenly when it opens out into floodplains where it briefly changes its name to the Ichenge and then ends life, fat and happy, as the Chobe, before being swallowed by the Zambezi at Kazungula.
To compound the incestuous nature of these waterways, the Okavango is linked to the Chobe system via the Selinda Spillway and the remaining northern river, the Savuti Channel, is a spill-over from the Linyanti Marsh. They are all pretty much the same river but in their diversity they also provide not only the life source for one of the most remarkable game densities in Africa but also three of the great watercourse enigmas of the region.
Linyanti Marsh (Image credit: African Bush Camps)
The first of these enigmas is the Linyanti Marsh. The Linyanti, after following a smooth, gentle, south-easterly course, stumbles over a volcanic fault line and dramatically changes direction by 90˚ to flow northeast. It is here while the river struggles to realign itself that the banks overflow and create the Linyanti Marsh, a smaller but no less attractive version of the Okavango Delta.
The papyrus-lined pools, the crystal-clear waters that flow quietly alongside riverine forests of jackal-berry trees and beyond which lie open grasslands and dry inland wooded areas, are deeply reminiscent of its more famous big sister. Only a small section of this marsh is open to the general public where the Chobe National Park has a short slice of river frontage. The rest is taken by private concessions with strict controls on the numbers of guests that each camp can host. This ensures a low volume of visitors, keeping this area remote and pristine. The lodges offer game drives, walks, night drives and boat and pontoon rides. Through African Bush Camps you can take a truly unforgettable helicopter ride over this wild marsh.
Elephants, Savuti marsh (Image credit~: Peter Comley)
The second enigma springs from the Linyanti Marsh and is a beguiling one. Set in the west of the 11,000 sq km Chobe National Park lies a river that is called a channel and which for a few decades flows powerfully, disgorging itself into a vast marsh, and then it retracts its charms leaving behind a parched stretch of grassland, which with some irony is still called the Savuti Marsh. The early explorers, missionaries and traders who passed this way contradicted each other as they described their experiences. The diaries of some, like David Livingstone, drew pictures of a paradise of waterways and an abundance of game, while others who came later depicted the Savuti Marsh and its southerly neighbour the Mababe Depression as arid and inhospitable.
Those who visited Savuti from the mid eighties through to the early part of this century will carry with them memories of desert-like aridity because the Channel stopped flowing in 1979 and within three years the pools had all dried and the animals had moved on. Then, almost miraculously, in 2008 the river started to trickle and then charge back down the Channel and flood into the marsh. Five years later large herds of buffalo and elephant luxuriate in the abundance of grass and water that the marsh provides; predator numbers started climbing steadily as their food base grew, and species like waterbuck returned, having been totally absent for the past 30 years. Now, within the last month or two, the channel has again stopped flowing and the Marsh has dried. Optimists predict that the flood is still on its way and the Marsh will refill this year. Others are not so sure.
What causes the Channel to ebb and flow on such a regular basis? Northern Botswana lies along a branch of the Great Rift Valley and geologists measure very regular, if imperceptible, earth tremors. Some believe that larger quakes could cause the ground to shift and block the flow of water. Surely, however, it is no coincidence that the average rainfall between 1972 and 2004 was the lowest on record and that when the rainfall again climbed, the Kwando and Okavango spilled over into the Channel once again. Last season’s rains were poor in comparison to recent years.
Rainfall figures rise and fall in reasonably predictable cycles and we now appear to be set for a dry spell. If the Channel flows again this year it will indeed be the right time to visit the marvel that is Savuti.
Buffalo on the banks of the Chobe River (Image credit: Tom Varley)
Which brings me to the third enigma; even when the Kwando is reduced to a stream, the Linyanti Marsh is but a stagnant swamp, and the Ichenge is nothing but a dry riverbed, the Chobe River itself is fat and happy. This abundance of water downstream of a dry river course is only part of the Chobe’s enigmatic status. It also flows both ways! This was discovered by some loggers who were based at Serondela before the National Park was declared. They were in the habit of pushing their logs into the river and floating them downstream towards the market in Livingstone. One windless day they threw them into the river and watched in amazement as their livelihood floated upstream.
The reason for this is that a fault line forms a rocky ridge across the Chobe and Zambezi Rivers, acting like a dam wall. The Zambezi when it strikes this ridge, pools and overflows down what is known as the Kasai Channel until it enters the Chobe where it dams against the ridge and backs upstream. As the flood ebbs the Chobe stops flowing and then slowly, as the levels drop further, it starts flowing in the expected direction towards the sea.
Whichever way the river flows, there is water in abundance and in the dry months it attracts game, especially elephants, from the drier areas. In turn these animals attract many tourists from around the world, making the Chobe the hub of the region’s tourism.
A game drive on the shores of the Chobe River (Image credit: Tom Varley)
With thanks to Shelly Cox of African Bush Camps for descriptions of Linyanti.
Editors note : It is hoped that in the near future these ‘great enigmas’ will join the ranks of the world’s RAMSAR sites.
Other articles in this series:
Paradise unveiled
A short history of the Falls
The sacred hills of the Matopos
The smoke that thunders
Valley of abundance
Superlative and unexplored
The great enigmas
Africa’s grand anomaly
The Middle Zambezi
The Zambezi’s final triumph
No comments:
Post a Comment