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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

IRSJ marks five years of championing social justice
2016-08-12

Description: IRSJ 5 year Tags: IRSJ 5 year

Members of the Advisory Board of the IRSJ,
Prof Michalinos Zembylas (Open University
of Cyprus), Prof Shirley Anne Tate (Leeds
University, England), and Prof Relebohile
Moletsane (University of KwaZulu-Natal),
listen to a speaker on the programme.
Photo: Lihlumelo Toyana

The Institute for Reconciliation and Social Justice (IRSJ) marked its fifth anniversary with a function on 27 July 2016 in the Reitz Hall of the Centenary Complex on the Bloemfontein Campus of the University of the Free State (UFS). Earlier that day, the Advisory Board of the IRSJ, chaired by Prof Jonathan Jansen, Vice-Chancellor and Rector of the UFS, hosted their annual meeting.

A new book was also launched, co-authored by JC van der Merwe, Deputy-Director at the IRSJ and Dionne van Reenen, researcher and PhD candidate at the IRSJ. It is entitled Transformation and Legitimation in Post-apartheid Universities: Reading Discourses from ‘Reitz’. The function featured not only reflections on the IRSJ, but a four-member panel discussion of the book and higher education in 2016.

The IRSJ came into being officially at the UFS in January 2011. Prof André Keet, Director of the IRSJ, said: “With a flexibility and trust not easily found in the higher education sector, the university management gave us the latitude and support to fashion an outfit that responds to social life within and outside the borders of the university, locally and globally.”

The IRSJ has not hesitated to be bold and
courageous in reforming ... traditional policies."

 

Prof Jansen went on to mention three things he finds appealing about the IRSJ: “Thanks to Prof Keet and his team’s vision and understanding of how important it is for students to have a space in which they can learn how to be, learn how to think, and learn how to contribute, the IRSJ has become a place where students can learn about things that they might not learn in the classroom. Second, it created, for the first time, a space where members of the LGBTIQ community could gather in one place. And third, it speaks to the intellectual life of the university, as evidenced by the research and publications produced over the past few years.”

Prof Jansen added: “The IRSJ will only be successful to the extent that we have safe spaces, courageous spaces, in which not only black students talk to themselves, but where black and white students talk together about their difficulties. If you’re entangled, you can’t get out of [that] unless you speak to the other person.”

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Prof Michalinos Zembylas of the Open University of Cyprus and member of the Advisory Board, said of the IRSJ: “The works produced by the institute in this short time have been valuable to this community and beyond, because they recognise the complexities of education, ... while pushing the boundaries of how to translate theoretical discussions into practical, everyday conditions. ... For example, the IRSJ has not hesitated to be bold and courageous in reforming some traditional policies in this university—remnants of an ambivalent past that reproduced inequality and disadvantage.

In reflecting on how the IRSJ came into being during her opening remarks, Dr Lis Lange, Vice-Rector: Academic at the UFS, said that it has always been “dedicated to transformation.” She added that it “gathered the energy and creativity of some of our most promising student leaders.” She concluded: “For me, the greatest success of the Institute, besides publications and local and international networks, is the fact that something that started in the margins is being asked today to come closer to the centre, to play a larger role in the structural transformation of the university.”

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