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Groundwater the saviour we need to take care of

20 January 2021 | Story Elsabe Brits | Photo SADC-GMI

Eekci Lukas_web read more — 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

Open letter from Prof Jonathan Jansen to all UFS students

2014-02-22

Dear Students of the University of the Free State

In the past four years there has emerged a new consensus on the three campuses of the University of the Free State (UFS) about the things that divide us – such as racism, sexism and homophobia. Students and campus leaders have worked hard to develop this new consensus in residences and in the open spaces on campus. There can be no doubt that new bonds of friendship have developed across the markers of race, ethnicity, class, religion and sexual orientation. I bear witness to these new solidarities every day on the campus.

You chose a white student to head up the transformation portfolio on the SRC. You chose a black captain to head up the university’s first team in rugby. You chose a white “prime” as head of residence to lead a predominantly black men’s residence. You chose a South African woman of Indian descent as Rag Queen and last week, a black student from Cape Town as the men’s Rag winner—choices not possible and never made before in our campus history. Many of you have intimate friends who come from different social or cultural or religious backgrounds. You learn together, share rooms together, pray together and party together. In other words, in the day to day workings of this university campus, you have demonstrated to campus, city and country that we can overcome the lingering effects of racism and other maladies in this new generation. You have helped create a university community inclusive of people of diverse religions, abilities, class and sexual orientation.

I have said this repeatedly that from time to time this new consensus will be tested – when a minority of students, and they are a small and dwindling minority, still act as if these are the days of apartheid. And when that consensus is tested as it was this week, and as it will be tested in the future, only then we will be able to assess the strength and durability of our progress in creating a new South African campus culture of human togetherness based on respect, dignity and embrace.

The real test of our leadership, including student leadership, is how we respond when our transformation drive is threatened.

Let me say this: I have absolute faith in you, as students of this great university, to stand together in your condemnation of these vile acts of violence and to move together in your determination to maintain the momentum for the Human Project of the University of the Free State. We have come too far to allow a few criminals to derail what you have built together in recent years.

There will, no doubt, be unscrupulous people on all sides of the political spectrum wanting to milk this tragedy for their own narrow purposes. There will be false information, rumours and exaggerations by those who wish to inflame a bad situation to gain mileage for their agendas. That is inevitable in a country that is still so divided.

I ask you, through all of this, to keep perspective. Two or ten or even twenty students behaving badly do not represent 30,000 students; a minority of violent and hateful persons do not represent the ideals, ambitions and commitments of the majority. At the same time, let us be realistic – anyone who thinks you can drive transformation without resistance clearly does not understand the difficult process of change.

The events of the week remind us, however, that we still have a long road to walk in deepening social and academic transformation at our university. Yes, we have invested hundreds of hours in training and mentorship; we have created new structures – such as the Institute for Reconciliation and Social Justice – to capture the energy and imagination of students driving transformation; we have created many opportunities for students to study and travel on this and other continents to enable cross-cultural learning; we have established formal and informal opportunities to dialogue about difficult issues on and off campus between students and their leaders; and we crafted new curricula to enable teaching and learning on the big questions of our times.

But this is clearly not enough, and so I have decided on the following immediate next steps:

We will meet for several hours next week to think about how we can deepen the transformation of our university after this terrible incident.
We will arrange a University Assembly on the events of the past week so that we speak with one voice on human wrongs and to re-commit to human rights and we will continue with open forum discussions during the months to come.
We will review the entire spectrum of programmes, from orientation to residence life to the undergraduate curriculum, to determine how effective our interventions really are in reaching all students with respect to basic issues of human rights.
We will review our media and communications strategy to determine how far and deep our messages on human rights travel across all sectors of the university community. In this regard it is important that the campus be blanketed on a regular basis with our condemnation of human wrongs and our commitment to human rights.
We will commission the Institute for Reconciliation and Social Justice to review the events of the past week and make recommendations on how we can improve the campus environment so that all students are protected from harm inside residences, classrooms and in open spaces of the campus.
We will take the questions raised during this week into the academic community and to the general staff of the university so that all personnel also engage with our own roles and responsibilities with respect to campus transformations.
We undertake to make annual report-backs on transformation to all stakeholders in public forums so that students and staff and external communities can track the progress of the university on matters of human rights on campus.

I wish to thank my staff for acting firmly as soon as this tragic event came to our attention. We worked through the night to find and identify the perpetrators. We traced the two students and immediately handed them to the police. They were expelled. And throughout this process we offered counselling and support to the victim of this violent act.

The two former students were expelled and will now face justice in the criminal courts. It is hoped that in the course of time they will come to their senses and seek restoration and reconciliation with the student they so callously harmed. They are not part of the university community anymore.

That is the kind of university we are.

Jonathan D Jansen
Vice-Chancellor and Rector
University of the Free State
20 February 2014

Note: The use of the word ‘campus’ refers to all three campuses of the UFS, namely the Bloemfontein Campus, South Campus and Qwaqwa Campus.

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