IF it’s a cloudless day and you’re flying south over the Mediterranean to Entebbe or Johannesburg, you can see why African rivers mean life to animals, communities and crops. For half the journey, the only hint of green will be near the banks of the Nile, the desert on either side – a bit of a contrast to the view from Glasgow to London where the earth is usually saturated with water in the patches not covered by buildings and roads, rivers abounding.

The Tugela is my favourite river in southern Africa. Its source is on the bleak Lesotho escarpment at about 10,000 feet, then it spills over the edge of the Drakensberg in a series of falls. In winter, these freeze and some heroes storm up the vertical ice with a terrordactyl axe in each hand and vicious toe spikes on their crampons, wreathed in testosterone fumes.

It lazily passes through Ladysmith of Boer War siege fame, almost hidden by weeping willows, then under the rumbling bridge at Tugela Ferry.

If you wanted to know the main recreational activities of some Zulus, the permanent police camp on the river bank would have given you a clue, its sign announcing Firearm and Stocktheft Unit. The surrounding barren hills encourage near-intolerable summer temperatures. The Church of Scotland hospital there used to have one small air conditioner in its operating theatre, the windows and doors of which the matron insisted be left open if there was no surgery taking place – leaving the stressed aircon trying to cool down the entire Tugela river valley.

The Orange or Senqu arises not far from the Tugela but then heads west for 1,300 miles and ends in the Atlantic amid the diamond bearing-silt of Oranjemund in Namibia. We often spent nights camped on its banks in Lesotho, bitterly cold but wakened at intervals by the equally chilling screams of wildcats.

By contrast, the Mzimvubu is a semi-tropical river and its leisurely flow suits the laid-back atmosphere of the little Wild Coast village of Port St Johns where it debouches into the Indian Ocean.

Near to midnight some years ago, having travelled south several hundred miles from Swaziland, we were about to cross over the Mzimvubu by its huge bridge near the port when we noticed two oil drums in the middle of the road, and became aware of a thunderous boom. Walking past the drums, our weak torchlight showed there was a problem – the entire middle span of the bridge was gone. Next morning, we watched a frightening flood that had risen 60 feet above its usual placid level.

The Zambezi has always left me queasy, perhaps due to the first time I crossed it. Kazungula was a ferry point on the huge river and the shortest way to reach East Africa from the south – shortest, not safest.

The crossing, not far from the Victoria Falls, was where four countries met – the Caprivi Strip of Namibia bordering Zambia on the north bank, Botswana and Zimbabwe on the southern one. With ever-changing politics, this meant travellers and local folk were, and still are, both anxious and wary when asked to show their passports and documents. Shortly after that first crossing, the reliable if far-from-graceful ferry was bombed to bits by the then-Rhodesian air force.

In Uganda, the Nile is really part of the family. I first walked around its exit from Lake Victoria at the Owen Falls dam near Jinja which was built by the British. Not long afterwards I was looking at a photograph of several army lorries on the dam road taken, not surprisingly, from a distance, which purported to be of Idi Amin’s men tipping bodies into the river below.

Nowadays we cross it on journeys to Kampala, always taking a photo of the Karuma Falls on the Victoria Nile for luck, and look down on it further north from Gordon Hill above Nimule in South Sudan when visiting relatives or attempting to reach Juba on the insecure main road.

A muddy stream at the bottom of our farm’s cassava field eventually empties into the Albert Nile. It widens into a muddy pond at one point and is rumoured to harbour a strong catfish which our son has been trying to catch for over a year. He has been warned that if it pulls him in, he may reach the Nile sooner than he expected.

Dr David Vost studied medicine at Glasgow University and is currently working at a hospital in Swaziland. He and his family live on a small farm in Northern Uganda near the Albert Nile. davidvostsz@gmail.com