Groundwater - A resource more valuable than gold

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What is groundwater and why is it important?

The excess soil moisture that saturates subsurface soil or rock and migrates downward under the influence of gravity. In the literal sense, all water below the ground surface is groundwater; in hydrogeologic terms, however, the top of this saturated zone is called the water table, and the water below the water table is called groundwater. (source: Encyclopedic Dictionary of Hydrogeology; 2009)

Groundwater has many benefits to human beings. It is usually cheap to develop because it’s generally of a good quality and widespread occurrence. Being stored underground where evaporation is minimized, it is a more reliable source than surface water in times of drought.

Where does groundwater come from?

Groundwater is an important part of the water cycle. It comes from rain, snow, sleet and hail that soak into the ground. The water moves down into the ground because of gravity, passing between particles of soil, sand, gravel, or rock, until it reaches a depth where the ground is filled, or saturated, with water. The area that is filled with water is called the saturation zone and the top of this zone is called the water table. The water table may be very near the ground’s surface or it may be hundreds of meters below.

Although groundwater exists everywhere underground, some parts of the saturated zone contain more water than others. An aquifer is an underground formation of permeable rock or loose material which can produce useful quantities of water when tapped by a well. These aquifers may be small, only a few hectares in area, or very large, underlying thousands of square kilometers of the earth’s surface.

Even if groundwater is not used by people, it may still play an important role in the local environment and sustain rural livelihoods that way. Plants may tap into it with their roots and animals may drink it when it comes to the surface as springs.

If groundwater is underground, how do we get it out?
Under natural conditions water in aquifers is brought to the surface through a spring or can be discharged into streams or wetlands. Water in aquifers is brought to the surface naturally by means of a spring, a borehole or can be discharged into lakes, streams or the ocean. We as humans can abstract groundwater through a borehole which is drilled into the aquifer.
Once a successful borehole has been drilled, we can equip it with any of the following equipment: (the choice is influenced by the specific intended use of the water, e.g. for drinking water, water supply to municipality, irrigation and other):
handpump – especially if yield of borehole is low, mainly in rural areas,
windpump – mainly on farms, can maintain higher yields,
electrical pump/diesel pump – usually when borehole yield is higher, higher assurance supply, or
playpump – effective when borehole yield is low, mainly for water supply at schools. (read more / watch the video about this innovative design at http://www.playpumps.org)
 
Boreholes require sophisticated technology with the right appropriate technical design, together with proper knowledge of the aquifer. Unfortunately, the importance of good quality borehole design and construction is often underestimated. The lifetime of a borehole and the efficiency of its functioning depend directly on the materials and the technology used. Borehole “failure” is often not linked to aquifer performance, but to the incorrect design and construction of the hole.

Groundwater in South Africa

Groundwater, despite its relatively small contribution to the total water supply in South Africa (~13%), represents an important strategic water resource. Owing to the lack of perennial streams in the semi-desert to desert parts, two-thirds of South Africa’s surface area is largely dependant on groundwater. In these water-scares areas, groundwater is more valuable than gold. Although irrigation is the largest user of groundwater, groundwater provides the water supply to more than 300 towns and smaller settlements.

In over about 90% of the surface of South Africa, groundwater occurs in hard rock that is rocks with no pore spaces. Here it is contained in faults, fractures and joints and in dolomite and limestone, in dissolved openings called fissures.

Hard rock aquifers are known as secondary aquifers because the groundwater occurs in openings which were formed after the rock was formed. Over the remainder of the country groundwater occurs in primary aquifers. These comprise porous sediments and soils where groundwater is contained in the spaces between sand grains. Primary aquifers are found in river (alluvial) sediments, in coastal sand deposits, and the Kalahari deposits. 

Groundwater Quality

One of the most important natural changes in groundwater chemistry occurs in the soil. Soils contain high concentrations of carbon dioxide which dissolves in the groundwater, creating a weak acid capable of dissolving many silicate minerals. In its passage from recharge to discharge area, groundwater may dissolve substances it encounters or it may deposit some of its constituents along the way. The eventual quality of the groundwater depends on temperature and pressure conditions, on the kinds of rock and soil formations through which the groundwater flows, and possibly on the residence time.

As a result the groundwater chemistry from various places in South Africa will differ depending on the aquifer in which it is found and may make the water unsuitable for certain uses. For example, water from the Malmesbury shales is unsuitable for most uses due to high total dissolved salts. Groundwater in granites (eg. in Limpopo) naturally contains fluoride in high concentrations.
It is essential to have the quality of the water from a borehole intended for domestic use tested before consumption. Even natural groundwater may contain substances which can make it unfit for consumption.

Groundwater Pollution

Just because water is underground does not mean that it cannot be polluted. Groundwater can be contaminated in many ways. Groundwater associated with coal deposits often contains dissolved minerals poisonous to plants and animals. Pollutants dumped in the ground, in landfills and at sites of animal husbandry or pollutants introduced below ground such as in unlined latrines and burial sites, may leak into the soil and work their way down into aquifers.

Pollutants include substances that occur as liquids like petroleum products, dissolved in water like nitrates or are small enough to pass through the pores in soil like bacteria. Movement of water within the aquifer is then likely to spread these pollutants over a wide area, making the groundwater unusable and spreading disease.

The Danger of Over Abstraction

While groundwater is an abundant resource, it does not mean we should waste it. The maximum quantity of groundwater that can be developed economically in South Africa is estimated at about 6 billion/m³ a year. Some groundwater resources take a long time to replenish. If too much groundwater is extracted too fast, it may become depleted. In coastal areas, fresh water, being less dense, floats on salt water. Over extraction of fresh water may allow salt water to replace it. Therefore, it is important to decide how much water can be extracted from an aquifer before it is developed.

Can we run out of groundwater?

Groundwater supplies are recharged naturally by rain and snow melt. That means we are only able to abstract as much water as that being recharged, otherwise the groundwater supply will run into a “deficit”. It is therefore possible that we can run out of groundwater, at least until the supply has been recharged again. This recharge process can take months, years or even hundreds of years. It is important to know how much water is available for abstraction from a specific aquifer BEFORE we start to utilise it. 

Classification of water in terms of where it is found

Meteoric water – water in circulation in the atmosphere
Surface water – water found in rivers, lakes, wetlands and the ocean
Subsurface water – all water found below the surface of the earth, including soil water, capillary water and groundwater
Groundwater – al water in the zone of saturation i.e. below the water table

Planet's Water Balance

(Source: National Geographic Sept 2002 – A thirsty planet)

Saline water – 97.5%
Sea water – 99.0%
Saline groundwater and lakes – 1.0%

Fresh water – 2.5%
Ice and snow – 70%
Groundwater – 30%
Lakes and rivers – 0.25%
Soil, wetlands and biota – 0.1%
Atmospheric water vapor – 0.04%

Become a hydrogeologist

Institutions offering formal qualifications in groundwater

DR KAI Witthüser and Jude Cobbing are hydrogeologists working for a consulting firm.

 

Though they dreamt of being famous soccer coaches or players, they decided to follow this exciting career and have never looked back.

They say there is a skills shortage in this industry and encourage anyone interested to consider hydrogeology as a career.

Basics

A hydrogeologist is also known as an environmental geologist or a geo-hydrologist.

Someone with a BSc (Honours) can earn R15000 a month and with 10 years experience, the monthly salary can go up to R45000.

Job description

Kai explains that as a junior you will do fieldwork, where you will supervise pump traffic contractors and drillers, as well as take samples and perform site visits for environmental impact assessments.

Senior hydrogeologists do risk assessment, hydrogeological modelling and interpretation of experimental data to conceptualise the geographical unit of water in the subsurface. They don't really work in the field - except when dealing with client liaison.

Jude describes the job as varied.

"You do a little bit of everything, from being outdoors, collecting samples, to working in the office or the lab. There is also a fair bit of travel. This industry is very diverse, so you can start off with geology and then do chemistry, mathematical modelling and environmental legislation, to mention a few. Essentially, it is the study of ground water in all shapes and sizes, its quality, and how much there is, and so on."

Pros and cons

"The pro is that you deal with a hidden resource that you have to conceptualise, preferably in 3D. Other pros are that it is a mixture of fieldwork and office work and you deal with a wide range of sciences - geophysics, chemistry, hydrology and geology," Kai says.

"The diversity of it, working indoors and outdoors, and there is a lot of work, as there aren't many people in the industry yet," Jude says.

"The cons are that it is sometimes difficult to prove your conceptual understanding and the red tape," Kai says.

"In South Africa it's still a new profession, though it is changing quickly, and sometimes our concerns are not taken seriously," Jude says.

Required studies and experience

Jude says an MSc in Hydrogeology is not the only qualification needed and there are various routes you can take.

Kai says the qualifications required vary across the country. At the University of Pretoria you would need to do a BSc in Geology, with an Honours in Hydrogeology, as well as further studies.

To follow this profession, you will have to register with the South African Council for Natural Scientific Professions.

Qualifications in a related environmental field and sufficient experience in hydrogeology are some of the requirements for registration.

Personality types

You need to have an open personality and enjoy teamwork. You should also be willing to compromise and be dedicated to your work.

Jude laughs, "You need a multiple personality disorder for this job".

An average day

There is no average day. Jude says it depends on what you are working on and you should expect the unexpected.

Kai says, "A junior's day will consist of fieldwork early in the morning, followed by returning to the office in the afternoon to collate data.

A senior will have meetings in the morning and then gather data to analyse, model and interpret. You would also have to write reports."

The best thing about the job

"Trying to make a difference with regard to environmental impacts on our water resources," smiles Kai.

"It's very interesting. There is never a dull day. You're working with a fundamental thing (water) and it's fun to work with," beams Jude.

The worst thing about the job

"Seeing your environmental concerns not taken seriously," Kai says.

"The lack of recognition in South Africa, the long travel and sometimes you work on site with extreme challenges," Jude says. -

SA Careerfocus

Groundwater Issues

National Groundwater Strategy

GROUNDWATER STRATEGY (GS)

 
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 Directorate: Water
Resource Planning
Systems
Private Bag X313
Pretoria
0001
Fax: +27 12 336 7303
E-mail: fourief [at] dwa [dot] gov [dot] za
  
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 No. 1 ‘Preparing for a new National Groundwater Strategy’
 No. 2 ‘Creating an Awareness of Groundwater’
 No. 3 ‘Planning for Water Resources – Groundwater’
 No.4 ‘The Monitoring of Groundwater Levels?
 No.5 ‘Groundwater Availability’
 No.6 ‘Artificial Groundwater Recharge’
 No.7 ‘Groundwater for Mining and Energy’

This section is directly made available from the Department of Water Affairs, Groundwater Home site, GS link:

http://www.dwa.gov.za/Groundwater/gs.aspx

The Groundwater Strategy (GS) is the outcome of a three-year consultative process, led by the Department of Water Affairs (DWA). It is designed to ensure that groundwater is recognised, utilized and protected as an integral part of South Africa's water resource. The Strategy is divided into a series of themes or chapters, each of which has a number of recommended actions which address the challenges raised in the theme. The Strategy is designed as an input document to the National Water Resource Strategy (NWRS) 2nd edition.

Status

The GS has been completed. If there are have any questions or comment please contact fourief [at] dwa [dot] gov [dot] za (Fanus Fourie)

Documents

The Groundwater Strategy, 2010 [PDF - 16.2 MB]

The following documents were produced to develop the Groundwater Strategy:

A Framework for a National Groundwater Strategy, February 2007 [PDF - 1.6 MB]

Literature Review: GRA1, GRA2 and International Groundwater Assessment Methods,  August 2009 [PDF - 1.9 MB]

A Proposed GRA3 Methodology, August 2009 [PDF - 1.4 MB]

Case Studies of Groundwater Use in South Africa: Groundwater Success Stories

Overview of Policy and Law pertaining to Groundwater in South Africa

Analysis of the Financial Impact of the Groundwater Strategy

Capacity Building Report, December 2008 , December 2008 [PDF - 500 KB]