SA’s search for new water sources .
Dropping dam levels are driving the search for alternative ways to quench South Africa’s thirst for this precious resource
IN RECENT years it’s been a question that’s haunted residents in the northern parts of South Africa. And with each passing month, as the soil became drier, the animals leaner and the crippling drought fiercer, it became more pressing. Now it’s the turn of those down south who are watching dam levels drop to near-devastating levels. What, everyone wants to know, happens when the water runs out?
Experts and ordinary South Africans alike are asking this question. Although torrential rain has brought some relief to the northern parts of the country, the Western Cape has had to implement severe restrictions to help address the water crisis.
On 1 February the City of Cape Town implemented level 3B restrictions, which means hosepipes are banned, sprinklers are a no-go and there are severe restrictions on watering gardens.
The worst water-wasters are receiving spot fines after city officials revealed water consumption needed to decrease by more than 100 million litres a day to below 700 million litres to ensure sufficient supply until the arrival winter rains.
But the restrictions come with their own set of problems, experts say.
“Already water restrictions are taking their toll on the construction industry and other businesses that are dependent on water, says Kevin Winter of the environmental and geographical science department at the University of Cape Town (UCT). “The consequences for the environment, society and the economy could be widespread. No one wants to talk about this and at this stage it seems senseless to project fear or panic.”
“Hopefully the rains will be prevalent from May,” says Professor Mathieu Rouault of the department of oceanography at UCT. “But if it doesn’t rain again this winter, [the consequences are] going to be dramatic.”
Of course, it’s the “if it doesn’t rain” that’s the problem. Is there a plan B or plan C?
LONG-TERM SOLUTIONS
The Western Cape provincial government’s department of environmental affairs and development planning has put measures in place to produce and store more fresh water. These include:
Increasing surface water resources
This refers mainly to the province’s rivers and dams. Part of this plan includes raising the walls of certain dams to increase water capacity and even building more dams to provide extra water storage.
But with the current collective dam levels decreasing at a rapid rate, surface water resources are limited and projected to last only about 100 days – should the level 3B water restrictions be upheld.
“For the moment, let’s hope we get significant rains – a miracle thunderstorm, as was the case on 20 April 2005 when we were in a similar position,” Winter says.
Tapping underground water resources
One way of relieving pressure on dams is to tap into natural underground water resources, such as drilling boreholes or accessing aquifers, but this isn’t a quick fix.
South Africa’s geology doesn’t favour underground water sources, water specialist Anthony Turton says.
An exception is the Table Mountain Group (TMG) aquifer system, which contains billions of cubic metres of water, according to scientist Chris Hartnady, who’s investigating potential water sources.
There are also substantial underground water sources near East London in the Eastern Cape and in North West province.
At this stage most of the extraction of water from the Cape Flats aquifer is being done privately, Winter says. The city is exploring the idea of a managed aquifer recharge (refill) – which involves recharging the aquifer with storm water.
“The best example we have of a managed aquifer is more than 35 years old already,” Winter says. “The town of Atlantis treats water through the sand aquifer on the West Coast and that water is returned to the town.
“I’m not sure how well it’s currently functioning. But it’s already being done – the intention is to achieve ‘water mining’ on a much larger scale.”
Groundwater extraction should be done sparingly, warns Xanthea Limberg, City of Cape Town mayoral committee member for informal settlements, water and waste services and energy.
“If too much groundwater is extracted too quickly, it may become depleted,” she says in a report.
“The uptake of boreholes and well points is useful in taking pressure off our dams at a time when they’re reaching dangerously low levels. But it’s important
that we utilise the water responsibly.”
Recycling wastewater
This process involves reusing water from water-treatment plants. Water from sewage and wastewater plants can be treated and reused as a way of saving on potable (drinkable) and freshwater resources where necessary.
The City of Cape Town can process only about six percent of treated wastewater and can sell this water to consumers for reuse on, for example, sports fields and golf courses, Winter says.
But it’s aiming to increase the amount of treated water to 15 percent.
WHAT ABOUT DESALINATION?
South Africa has a huge coastline – water as far as the eye can see. Why not harvest seawater to meet our needs?
Desalination involves removing salt and minerals from seawater, making it suitable for human use and consumption. But although widely used around the world, experts say it’s not a useful tactic in South Africa because of its high cost.
The Mossel Bay desalination plant is the largest in South Africa, and was built at a cost of R210 million.
“To go the desalination route would be very expensive. It would cost a lot of energy, it’s not good for climate change and will be a great contributor to pollution as well,” Professor Rouault says.
“It will use electricity and we want to save electricity. We don’t want to contribute to climate change; it’s already bad enough as it is.”
Desalination is widely used in other countries including Saudi Arabia, the United Arab Emirates, Spain, Greece, Italy, China and Australia.
“While desalination is offered as a ‘fix’, examples like that of Perth in Australia – a city that’s comparable to sunny Cape Town – suggest that desalinated water is more than three times more expensive than stored freshwater.
“Despite massive investment in water desalination, only 18 percent of Perth’s needs are met by desalination,” Winter says.
BRING IN THE ICEBERGS!
Another idea that pops up often is towing icebergs to provide fresh water. A few years back French engineer Georges Mougin came up with the idea of tying a rope around a six million-ton iceberg in Antarctica and dragging it to Africa, where it would melt into drinkable water.
His plan included using 3D computer data and algorithms to test his theory virtually, but putting this theory into practice remains a pipe dream.
In 2011 it was estimated that it would cost €8 million (then about R83,8 million) just to transport an iceberg from Newfoundland in Canada to the Canary Islands off northwestern Africa.
Experts are sceptical. “I can’t get my head around this one,” Winter says. “Icebergs are massive, with most of the structure lying beneath the surface. Towing anything in an ocean that’s volatile is a risk at best. Why would we want to damage our ecosystem any further?”
Professor Rouault says getting an iceberg to cross the Agulhas current, which runs along the east coast of Africa, would be impossible.
“Transporting an iceberg from the Antarctic would be too far and not practical at all,” he says. “Even if we managed to get an iceberg across the current, what do we do with the water?
“Would we get a pick and buckets to pick at the iceberg? It would be extremely difficult to extract that water – it’s just not practical.”