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20 January 2021 | Story Elsabe Brits | Photo SADC-GMI
Dr Eelco Lukas, a geohydrologist, is the Director of the Institute for Groundwater Studies at the University of the Free State (UFS).

Nearly two-thirds of South Africa depends solely or partially on groundwater for domestic needs, and in a water-stressed country this source is becoming increasingly important. But we need to use it wisely.

Dr Eelco Lukas, a geohydrologist, is the Director of the Institute for Groundwater Studies at the University of the Free State (UFS). He explains that all the natural water found in the earth’s subsurface is called groundwater. “When we look hard enough, we can find groundwater almost everywhere.  But that does not mean that we can start pumping groundwater at any location.  In many places, the amount of groundwater available (yield) is so little, or the water so deep that it is not financially viable to pump it.  Another problem might be the quality of the water.”

Numerous towns and communities depend solely on groundwater and many towns use a combined supply of surface and groundwater. When the town or settlement is far from any surface water and groundwater is available, boreholes are drilled. Depending on the size of the settlement, the boreholes are equipped with electrical or hand pumps.

Most of the big cities use surface water in their water pipes. Almost all big cities worldwide are located close to a supply of freshwater.  Cape Town has drilled many boreholes in the past two years to augment the city’s water supply.  However, problems can arise when a borehole is drilled for a community with a certain number of people, and soon there are more people than the borehole can supply for. It is not so much a case of the ‘borehole drying up’ but that the capacity has been exceeded.

Misconceptions about groundwater

With increasing drought and water restrictions being imposed, many people opted for their own borehole. When so many people draw water from the same source, the water table will drop. It can be compared to drinking a milkshake, but when five other people also drink with straws from the same milkshake, all will be left thirsty. 

Dr Lukas says because groundwater is something that cannot be seen with the naked eye, the general public has many misconceptions about groundwater. Some people think that you can drill a hole just anywhere and that you will find water, while others believe that water flows in underground rivers. It generally moves very slowly, only a few metres per year. And if it rains in a specific place, it does not mean that water will reach a particular borehole.

“Sustainable groundwater usage is the certainty that enough groundwater is available in years to come.  Sustainability is dependent on two external factors, namely demand and supply.  Unfortunately, both these factors are beyond the control of the geohydrologist.  When enough water is available for a community, the chances are that the community starts to grow, thereby enlarging the demand.  If the higher demand cannot be met, sustainability is no longer possible. When a change in rainfall pattern results in a decline of the precipitation, the groundwater recharge will become less, resulting in a lower supply of water.”


How does water move?

Groundwater moves through openings in the subsurface. These openings can be large (a millimetre to a few centimetres), but most of the time they are small, only a fraction of a millimetre. These are called pore spaces.  Water can only move through the pores if the pores are connected to other pores. The ease with which water can move through the rock is called hydraulic conductivity and is expressed in volume per area per time.  

Dr Lukas explains that different types of rock have different sizes of pore openings. The speed at which water can move through unconsolidated materials ranges from 1 000 m/d (gravel) to 10-8 m/d (clay). Consolidated materials range from 1 000 m/d (highly fractured rock) to 10-7 m/d (shale).  Sandstone, a rock that occurs in abundance in South Africa, has a typical hydraulic conductivity of 10-2 m/d, meaning that the speed at which the water flows is around 1 cm/d, which is less than 4 metres per year.  

In a way, you can compare groundwater flow to a pipe filled with marbles.  If you remove one marble at the one side, a marble may enter the pipe on the other side.  Although it may take the marble a long time to reach the other side of the pipe, the movement of the marbles is noticed almost immediately, says Dr Lukas.

Before groundwater is used, experts must make sure that it is suitable, Dr Lukas says. This is one of the areas that the Institute of Groundwater Studies at the UFS excels in. The institute also provides a complete service to industries through field investigations, the development of specialised field equipment, a well-equipped commercial and water research laboratory, and a number of computer models for the management of the aquifers, protecting them from pollution.

There are different standards for different purposes.  The best-known standard is the drinking 
water standard (SANS 241).  The water is tested for microbiology, as well as for the physical, aesthetic, operational and chemical determinants, and for the taste and colour.

There are several geophysical methods to locate groundwater.  “It must be stressed that the geophysical methods do not actually indicate places with water, but rather places where the geology and geological features support the presence of groundwater,” he says.

Different techniques are used to ‘look’ at different depths.   Water found close to the surface (upper 20 m) is often young water, meaning that it has been recharged not too long ago.  Because it is so close to the surface, it is vulnerable to contamination.   Deeper water is probably a bit older and because it is farther below the surface, it is more protected against surface contamination and the quality of this water is generally good.  Really deep groundwater (> 200 metres deep) will be even older and may have elevated salt content due to the long residence time of the water.

How much groundwater do we have?

Groundwater is a significant source of water, and in some parts of the country the only source of potable water.  According to the Department of Water Affairs and Sanitation, the most recent estimate of sustainable potential yield of groundwater resources at high assurance is 7 500 million m³/a, while current groundwater use is estimated at around 2 000 million m³/a. Allowing for an underestimation on groundwater use, about 3 500 million m³/a could be available for further development.  Unfortunately, if there is a shortage of water on one side of the country, it cannot be supplemented with water from the other side.
 
With a drought, the amount of water falling from the sky is below average, which means that the available water to recharge is also less. With less recharge water, the groundwater levels will decline.  To make things worse during a drought, groundwater users will pump more water to make up the deficit in rainfall, thereby accelerating the drop in water levels.

“Groundwater can be used to help humanity. The pore space in aquifers can be used to store water during a wet period, to be used later during a drought. This is called water banking, where water is injected into the aquifers (artificial recharge) during a period when there is enough water and pumped from the same aquifer during a period of water shortage,” says Dr Lukas. 

News Archive

“To forgive is not an obligation. It’s a choice.” – Prof Minow during Reconciliation Lecture
2014-03-05

“To forgive is not an obligation. It’s a choice.” – Prof Minow during the Third Annual Reconciliation Lecture entitled Forgiveness, Law and Justice.
Photo: Johan Roux

No one could have anticipated the atmosphere in which Prof Martha Minow would visit the Bloemfontein Campus. And no one could have predicted how apt the timing of her message would be. As this formidable Dean of Harvard University’s Law School stepped behind the podium, a latent tension edged through the crowded audience.

“The issue of getting along after conflict is urgent.”

With these few words, Prof Minow exposed the essence of not only her lecture, but also the central concern of the entire university community.

As an expert on issues surrounding racial justice, Prof Minow has worked across the globe in post-conflict societies. How can we prevent atrocities from happening? she asked. Her answer was an honest, “I don’t know.” What she is certain of, on the other hand, is that the usual practice of either silence or retribution does not work. “I think that silence produces rage – understandably – and retribution produces the cycle of violence. Rather than ignoring what happens, rather than retribution, it would be good to reach for something more.” This is where reconciliation comes in.

Prof Minow put forward the idea that forgiveness should accompany reconciliation efforts. She defined forgiveness as a conscious, deliberate decision to forego rightful grounds of resentment towards those who have committed a wrong. “To forgive then, in this definition, is not an obligation. It’s a choice. And it’s held by the one who was harmed,” she explained.

Letting go of resentment cannot be forced – not even by the law. What the law can do, though, is either to encourage or discourage forgiveness. Prof Minow showed how the law can construct adversarial processes that render forgiveness less likely, when indeed its intention was the opposite. “Or, law can give people chances to meet together in spaces where they may apologise and they may forgive,” she continued. This point introduced some surprising revelations about our Truth and Reconciliation Commission (TRC).

Indeed, studies do report ambivalence, disappointment and mixed views about the TRC. Whatever our views are on its success, Prof Minow reported that people across the world wonder how South African did it. “It may not work entirely inside the country; outside the country it’s had a huge effect. It’s a touchstone for transitional justice.”

The TRC “seems to have coincided with, and maybe contributed to, the relatively peaceful political transition to democracy that is, frankly, an absolute miracle.” What came as a surprise to many is this: the fact that the TRC has affected transitional justice efforts in forty jurisdictions, including Rwanda, Sierra Leone, Cambodia and Liberia. It has even inspired the creation of a TRC in Greensborough, North Carolina, in the United States.

There are no blueprints for solving conflict, though. “But the possibility of something other than criminal trials, something other than war, something other than silence – that’s why the TRC, I think, has been such an exemplar to the world,” she commended.

Court decision cannot rebuild a society, though. Only individuals can forgive. Only individuals can start with purposeful, daily decisions to forgive and forge a common future. Forgiveness is rather like kindness, she suggested. It’s a resource without limits. It’s not scarce like water or money. It’s within our reach. But if it’s forced, it’s not forgiveness.

“It is good,” Prof Minow warned, “to be cautious about the use of law to deliberately shape or manipulate the feelings of any individual. But it is no less important to admit that law does affect human beings, not just in its results, but in its process.” And then we must take responsibility for how we use that law.

“A government can judge, but only people can forgive.” As Prof Minow’s words lingered, the air suddenly seemed a bit more buoyant.

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