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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

Publication on indigenous knowledge systems
2005-10-21

 

 

Dr Otsile Ntsoane (acting Director: IKS, Department of Science and Technology) and Prof Philip Nel (Director:  Africa Studies at the UFS and guest editor of the publication) at the launch of the publication

UFS launches most comprehensive publication on indigenous knowledge systems
A unique collection of essays on Indigenous Knowledge Systems (IKS) was launched yesterday (20 October 2005) by the University of the Free State’s (UFS) Programme of Africa Studies.

The essays are published as a special edition of INDILINGA, the African Journal for Indigenous Knowledge Systems and is an outcome of the colloquium on Indigenous Knowledge Systems that was presented last year by the UFS Director of Africa Studies in cooperation with the National Research Council.

“The amount and diversity of materials on IKS brought together under one cover is unique as there are no other South African publications of this magnitude on this issue.  It contains papers of international experts on IKS such as Prof Fritz Wallner from Austria and Prof Gayatri Spivak, foremost postcolonial theorist from India,” said Prof Philip Nel, Director of Africa Studies and guest editor of the publication.

“The publication is a rich source field for students and scholars to exploit because most of the sources quoted in the articles are recent, fresh and relevant.  The contributors are largely people responsible for managing, fostering and studying IKS in a responsible manner,” said Prof Nel.

“An added value of the publication is the inclusion of the policy document on IKS that was adopted by Cabinet in November 2004,” said Prof Nel.


“Millions of people in South Africa are faced with the painful choice of abandoning their heritage.  In this choice, the study and management of IKS has a major role to play; on the one hand, to encourage as much assimilation of traditional knowledge as possible into the modern systems, and on the other hand to provide a “language” and a “grammar” for indigenous people through which they can access modernity,” said Prof Nel.

The IKS debate involves questions of African identity, protection of indigenous communities and practices, political aspects as well as the scientific integrity of the enterprise. 

The publication displays the range of burning questions that have to be resolved in this field such as mainstreaming IKS in academic debate and practice, recognition and protection of the knowledge holders, bio-prospecting and bio-piracy, bio and ethnic healing, lack of textbooks and field manuals, etc and will prove worthwhile for future researchers.

 “One of the main reasons for publishing this volume is the fact that IKS should be studied not only to provide a sense of pride in the past, or  to engender respect for indigenous peoples, but also to enable people in indigenous mind sets to make a better transition into the world of science and technology,” said Prof Nel.

The guest speaker at the launch was Dr Otsile Ntsoane, acting Director of IKS at the Department of Science and Technology.  In his speech Dr Ntsoane stressed the symbolic and concrete value of the publication.  “The publication can have a great social impact and the research results can contribute to chancing the economic landscape of South Africa,” he said.

The publication can be purchased at R150 per copy.  For more information, Ms Steffi Cawood, Programme Coordinator for Africa Studies at the UFS can be contacted at (051) 401-2614.

Media release
Issued by:Lacea Loader
Media Representative
Tel:   (051) 401-2584
Cell:  083 645 2454
E-mail:  loaderl.stg@mail.uovs.ac.za
21 October 2005
 

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