letting nature back in

One of the most beautiful fresh water pans in the northern Zululand region (Maputoland) of KwaZulu-Natal is the Inyamiti Pan in Ndumo Game Reserve.  The pan is fringed by fever trees with their pale yellow bark reflecting in the water, especially in summer when the water level is high.

The pans and marshes of Ndumo Game Reserve are fed by the Great Usutu River (which forms the border with Mozambique) and the Pongolo River. The confluence of the two rivers is just after they flow out of the reserve. As the river levels drop dramatically in the winter months so do the water levels in the pans, with the smaller pans drying up completely. In Inyamiti Pan, which is about 4.5 km (3 miles) in length, enough water remains for hippos and crocodiles to spend the winter there, while many birds feed on the exposed mud banks and in the shallower waters, with several bird species nesting on the banks during the winter.

However, the above photo was taken in summer, in fact as far back as 1976. The original photo was a slide (transparency) taken by my father on one of our family trips to the reserve.

Also taken in the summer of 1976, this view (above) of the Great Usutu River is taken from the famous Red Cliffs (named for the red sand) overlooking the river and across to Mozambique on the far side. Looking at this photo taken when the river was pretty full, it is hard to believe that the river drops so much in the dry months of winter that it is possible to walk across it as it is only ankle deep.

Although this post focuses on lakes and dams, they are usually so dependent on river dynamics that it is hard to divorce them from this context. An exception though is Lake Sibaya, also in Maputoland, which is South Africa’s largest freshwater lake. The lake gets its water from runoff and seepage from the high dunes (between Kosi Bay and Sodwana Bay) that separate it from the Indian Ocean and no river or stream flows into or out of the lake. There is evidence that at some point in the past the lake was connected to the ocean by a river.

In the winter months Lake Sibaya is often the only permanent surface water in the area and it is home to hippos and crocodiles and many other aquatic species including water birds. Of the 279 species of bird recorded at the lake, 62 species are closely associated with the lake through their roosting, feeding or breeding activities.

A small inlet of Lake Sibaya is close to one of the high vegetated dunes that separate the lake from the ocean. Seepage and runoff from the dunes, which reach a height of 165 m, form the lake’s primary source of water. The dense coastal forest on the dunes provides habitation for a variety of creatures. The white dots visible in the trees to the right of the photo reveal the presence of white-breasted cormorants that roost communally in these trees at night.

The lake is particularly tranquil at sunset as birds fly to their roosting sites and hippos grunt from the open water. The surface area of Lake Sibaya is estimated to be about 7 750ha.

Moving further south to Mkhuze Game Reserve – which although inland from the coast (and a bit north of Lake St Lucia) is still on the coastal plain forming part of the iSimangaliso Wetland Park – I take you on a visit to Nsumo Pan. Nsumo is another large and beautiful freshwater pan, home to hippos and crocodiles and many water birds, and providing water to the many other animals in the park. Despite its size, being over well over 14 km (9 miles) in length, Nsumo Pan too is affected by the seasonal variations in water availability. The pan reduces substantially during winter, being mostly mudbanks drying out to extensive areas of sun-baked clay.

Nsumo Pan receives most of its water from back flooding up channels from the Mkhuze River, which forms part of the northern border of the reserve, and from the Umsunduzi River, which flows on the southern side of the reserve.

(For a map of the towns, rivers and lakes and a map of the protected areas of Maputoland (Northern Zululand) see https://africawild-forum.com/viewtopic.php?t=10293.)

Interestingly, Reg Gush, in his book Mkhuze: The Formative Years (2000), says that it is only recently that the Mkhuze River altered its course to flow into the Nsumo Pan (timeframe unclear but at least by 1960). Previous to this, in the course of the cycle of the seasons and the fluctuations between drought and flood, the pan would seasonally dry up entirely. It is only since the river has changed course, resulting in a rather more permanent supply of water, that hippo have been able to live permanently in Nsumo Pan.

In the left of the above photo, a pod of hippos is just visible in the water close to the shore of Nsumo pans lined with fever trees (Vachellia xanthophloea).

Taking a closer look (via a zoom lens) at some of the hippo who, as usual, were spending the day in the water at Nsumo Pan in January 2015 when the pan still had sufficient water.

During the severe drought culminating in 2016, the Mkhuze River itself ceased to run and the pans, including Nsumo, dried out. At Nsumo Pan nearly 30 hippos huddled together in a central muddy patch and a trickle of water pumped from a borehole was piped there to keep them alive. In times past hippo were able to migrate to find water, finding their way north to the Pongola River for example, or south to St Lucia, but such migrations are no longer possible due to denser human settlements and other developments.

A young conservationist, James Cleland, made a video of his experience of seeing the hippos in the nearly dry Nsumo Pan in November 2016. You can see his video here: https://www.youtube.com/watch?v=eWs3DIwBad8

In his book on the early years of Mkhuze Game Reserve, Reg Gush quotes or relates terrifying stories of extremes of drought and flood that affected the reserve. The effect on animals could be severe with dozens of animals dying from hunger or thirst in times of drought, or getting bogged down and perishing in the mud as the pans dried out, or being drowned in rising waters or swept away when the Mkhuze River came down in torrential flood. In a flood the river could be transformed from being relatively to dry to a raging torrent within hours with walls of flood water charging down the riverbed bearing uprooted trees and other debris in surging waters.

He notes that by the late 1950s as increasing amounts of water upstream in the Mkhuze River were taken for irrigation for agriculture the amount of water reaching the reserve reduced making the impact of subsequent droughts even more severe.

I took the above photo in December in 2013 a few years before the severe drought that affected much of KwaZulu-Natal and other parts of the country too. Fever trees are adapted to survive brief periods of inundation and can withstand drought up to a point.

This view over Nsumo Pan is towards some of the large reedbeds providing nesting sites for water birds on the opposite shore. Mkhuze supports many waterbirds including South Africa’s only breeding colony of pink-backed pelicans, in addition to species of herons, cormorants, geese, ducks and waders. Fish eagles are resident, and we have seen a visiting osprey (a non-breeding migrant) at the pan.

A small group of white-faced whistling ducks in shallow waters near the shoreline at Nsumo Pan. Mkhuze is known as a birding hotspot and over 400 species of birds have been recorded at the park.

And moving further south and closer to home and to more domesticated environs, small farm dams can be important sustainers of many forms of aquatic life. The farmlands of the KwaZulu-Natal farmlands are dotted with small dams.

This small farm dam is in a hollow below an indigenous forest patch on a small ridge. Water from this afforested ridge seeps down into the dam supplying it with water, even during the dry winter months. The trees visible in the photograph are all imported alien species.

We spotted a pair of shy yellow-billed ducks swimming towards the small rushes on the far-side of the dam.

Here is another farm dam but on the other side of Pietermaritzburg in the drier thornveld region with thorn trees dotting the grassland on the distant hillside.

We used to take our dogs walking in a plantation a few miles from where we live. On the edge of the plantation is a patch of grassland sloping down to a small a dam with a small wetland below that. We were amazed one morning to see from a distance two otters apparently frolicking in the dam. On a subsequent visit we were sitting quietly watching the dam with our two dogs on leads when one of the otters swam up to a partially submerged log and climbed out, keeping a beady eye on us. It is a spotted-neck otter, a species that lives only in fresh water, unlike the Cape clawless otter that survives in both fresh water and marine habitats. Sadly, the numbers of spotted-necked otters are in decline, largely due to habitat loss and water pollution.

At the same dam a pied kingfisher was perching in a dead pine tree that was still carrying many pine cones. Periodically the kingfisher would fly out to hover high over the water in one spot looking for prey. If prey is spotted the kingfisher drops vertically plunging into the water to grasp its quarry.

Moving closer to home and reducing the size of the fresh water pond to only a couple of metres in diameter, our small garden pond also provides sustenance to a surprising variety of insects, water spiders and several species of frogs. It also attracts birds to drink and bathe in the shallows.

After draining our pond about two years ago to fix a leak, we had to re-establish its vegetation to achieve the right balance to avoid an overgrowth of algae. After much searching we were finally able to source the lovely indigenous floating hearts lily, Nymphoides thunbergiana. The floating leaves not only help regulate the temperature of the water but also provide landing platforms for insects and spiders. The small yellow flowers also attract pollinators.

The plants in and around our pond are all indigenous. Attracted to the pond are several species of dragonfly and damselfly, always a pleasure to see. It is surprising how after a time aquatic species such as water skimmers and river boatmen arrive in the pond. I have no idea how they get there.

Moving to even smaller still, we also made a water feature to break up a rather boring brick-paved area outside our back door. Several species of frog visit and even spawn there and birds come to drink from the large pot in which we have set a small fountain using a tiny submerged pump to circulate the water. Once the water feature was in place, we found that we needed to create a low roof over the water feature as it was getting baked in the sun. The roof is made out of narrow poles (lattes) and the water feature has a rather eccentric appearance – we sometimes refer to it as our Spanish wishing-well.

Despite the circulating water and the semi-shade from the roof, black slimy algae developed and eventually entirely coated the outside of the pot. While we were still wondering what to do about it, help arrived in the form of tiny fresh-water snails. A few can be seen on the lip of the pot in the photo. These snails feed on the algae and keep the pot clean. Perhaps the snails arrived in a plant that that we added to the water-feature from the pond.

Even a small container of water and plants can turn into a mini-ecosystem if the conditions are right. With any garden water feature or pond it is important to use native species of water plants. Many exotic species of water plant are highly invasive and it’s not worth taking the risk of our garden pond plants escaping or being transported to contaminate and clog up open waterways.

The eastern side of South Africa, including much of KwaZulu-Natal, has benefited from the current La Niña weather pattern in the form of decent rain this past summer. That fact and these photos focussing on lakes and ponds might create the impression that South Africa is doing okay regarding its supply of fresh water, but in much of the country – even without the prolonged drought in several regions  – many of the rivers are not perennial and river beds are mostly dry apart from in exceptional times after floods.

A dry river bed near Willowmore in the Eastern Cape photographed in October 2017. The fallen trees on the banks are evidence of a previous flood.

The Beersvlei Dam in the Eastern Cape was built in the late 1950s to control flood waters flowing into the Groot Rivier that joins the Kouga River near Patensie just below the Kouga Dam. It was not built as a storage dam as salination problems result if the water is stored for long periods. Due partly to some upstream weirs and largely to reduced rainfall in recent decades the dam has become pretty much obsolete. The last time it nearly reached capacity was in 2001.

Generally, dams in the Eastern Cape are currently at low levels with a water crisis in the metropolitan area of Nelson Mandela Bay, which includes the city of Gqeberha (formerly Port Elizabeth). The large Kouga Dam has been at a low level for years and is currently at 4.3% of its capacity with only 1.5% being useable. This is the lowest level the dam has reached since it was built in 1969. Another large dam responsible for much of the drinking water for Nelson Mandela Bay, the Impofu Dam on the Kromme River, is currently at 15% capacity as the region enters winter, which is the dry season.

The Orange-Fish tunnel (named for the Orange and Fish rivers), which is 82 km in length, brings a small measure of relief as it is used to transfer water from the Gariep (Orange River) Dam to Nelson Mandela Bay Metro supplementing supplies to other towns and irrigating farmlands along its route. The Orange-Fish tunnel first opened in 1976.

(For data on dam levels in the Eastern Cape that are updated weekly see https://sawx.co.za/state-of-dams/eastern-cape-province-dam-levels.php.)

A view of the Kouga River, which is substantially dry, not far from where it enters the Kouga Dam – this photo was taken from the road through the Baviaanskloof, in springtime in October 2016.

Many Eastern Cape towns and villages, including Makhanda (Grahamstown), Graaff Reinet, Bedford and Queestown, have had erratic water delivery problems and water shortages for years, with not only the drought to contend with but severe infrastructure problems too. Some suburbs and townships have had extended periods with no water, relying on water delivery by tanker as taps run dry.

Above is a view of the general aridity in the vicinity of Graaff Reinet, taken from Desolation Valley. The dark green lines in low lying land are bands of sweet thorn trees along the banks of rivers that were dry when this photo was taken in October 2019. The nearby Nqweba Dam on the Sundays River, the main source of water for the town of Graaf Reinet is currently at 8.4% of its capacity.

As illustrated by the above photo, farming and agriculture, and impoverished rural populations too, have been hard hit by the prolonged drought in Eastern Cape, a province that has also been very badly effected by Covid-19 infections over the past year. And now an entire metro is in crisis. For a recent article on the unfolding water emergency in the Eastern Cape see here and an opinion piece see here.

Other Karoo regions including in the Northern Province, parts of the Free State and parts of the Western Cape are also in ongoing crisis conditions as a result of the seven-year drought with no relief in sight. Livestock losses have been devastating, while animal fodder is being trucked in for the surviving animals. Water too is being trucked in to many areas as well as food parcels for farmers in some areas.

But to end, here is a photograph of the Bloemhof Dam on the border between the North West and Free State Provinces. It is one of the largest dams in South Africa and is currently 100% full. The dam is on the Vaal River, downstream of the Vaal Dam near Johannesburg.  The Vaal River rises east of Johannesburg and flows westwards a distance of 1120 km to join the Gariep (Orange) River near Douglas in the North Cape Province. The Gariep River rises in the Drakensberg and travels 2,300 km on its westward journey to join the South Atlantic Ocean.

This photo was taken in March 2014 just after sunset at a campsite at Bloemhof Dam where we stopped overnight when returning home from visit to Botswana. The long bridge carried thunderous trucks passing over it all through the night, a far cry from the freshwater pans of Maputaland.

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Sources:

Chittenden, Hugh, Davies, Greg & Weiersbye, Ingrid. 2016. Roberts Bird Guide: Illustrating nearly 1,000 Species in Southern Africa (2^nd edition). Cape Town: Jacana.

Ellis, Estelle & Ferreira, Deon. 2021. Eastern Cape drought: Nelson Mandela Bay’s dying dams. Daily Maverick, 2 May. https://www.dailymaverick.co.za/article/2021-05-02-eastern-cape-drought-nelson-mandela-bays-dying-dams/

Gush, Reg. 2000. Mkhuze: The Formative Years. Hilton: Reg Gush.

iSmangaliso Wetland Park. [n.d.] Lake Sibaya. https://isimangaliso.com/jewel/lake-sibaya/

Krause, Tanya. 2021. Karoo drought takes its toll on agriculture. SABC News, 31 March.https://www.sabcnews.com/sabcnews/karoo-drought-takes-its-toll-on-agriculture/

Mahlalela, P.T., Blamey, R.C., Hart, N.C.G. et al. 2020. Drought in the Eastern Cape region of South Africa and trends in rainfall characteristics. Climate Dynamics, vol 55, 2743–2759. https://link.springer.com/article/10.1007/s00382-020-05413-0.

Ngam, Roland. 2021. Crisis mode: It’s time to sound the alarm on the Eastern Cape water shortage. Daily Maverick, 11 May.  https://www.dailymaverick.co.za/opinionista/2021-05-11-crisis-mode-its-time-to-sound-the-alarm-on-the-eastern-cape-water-shortage/?tl

Pooley, A.C. 1967. Bird/crocodile and bird/hippopotamus commensalism in Zululand, Ostrich: Journal of African Ornithology, vol. 38:1, 11-12. https://doi.org/10.1080/00306525.1967.9639469

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Posted by Carol