14) PRECIOUS WATER
South Africa is extraordinarily rich in natural resources -
except for water. Water is a vital, but scarce resource,
distributed unevenly in time (frequent droughts alternate with
periods of good rainfall) and space (the eastern half of the
country is markedly wetter than the western half). Increasing
demand for water, and decreasing water quality, make careful
water management a priority in our country.
RAINFALL
Our average rainfall is less than 500 mm a year, with the driest
part of the country receiving less than 200 mm/year and the
wettest receiving more than 2 500 mm/year! Rain does not always
fall where it is most needed, and some areas of high demand, such
as Gauteng, receive less water than they need. Most rain falls
in the narrow belt along the eastern and southern coasts. The
rest of the country receives only 27% of South Africa's total
rainfall. In addition, hot, dry conditions result in a high
evaporation rate.
Water is thus a very scarce resource in South Africa. Large scale
engineering has been used to store water behind dam walls, and
to distribute water from regions of plenty to regions of need
(see "Intercatchment transfer", below).
RIVERS
There are few natural lakes in South Africa. We depend on rivers,
dams and underground water for our water supply. Approximately
75% of the water flowing from South Africa into the sea occurs
along the eastern and southern seaboards where many short rivers
occur. Flowing from east to west is the largest river in the
country, the Orange River, which drains most of the rest of the
country. Its water comes from sources in the Drakensberg and
Maluti Mountains, and it flows into the Atlantic ocean on the
West coast.
DAMS
About half of South Africa's annual rainfall is stored in dams.
We have 550 government dams in South Africa, with a total
capacity of 37 000 million m3.
Dams have both positive and negative ecological impacts. They can
be beneficial in that they regulate the flow of a river, reducing
flood damage, and contributing to a perrenial rather than
seasonal flow. In addition, sediment is deposited in a dam, and
the growth of aquatic plants means that excess nutrients are
removed from the water. Thus water leaving a dam might be cleaner
than water entering it. Negative ecological impacts include a
reduction in strong water flow which reduces the river's scouring
ability. This, in turn, can lead to silting of estuaries.
South Africa's landscape is not well suited to dams. There are
few deep valleys and gorges, with the result that most dams are
shallow with a large surface area. Together with the hot, dry,
climate, this results in much water evaporating from dams. In
addition, the high silt load (a result of an arid climate, steep
river gradients and poor farming methods) of our rivers means
that the capacity of South Africa's dams is quickly reduced as
they become silted.
The rivers of the western Cape are an exception, and carry
relatively little silt.
WATER ABSTRACTION
A growing problem for South Africa's rivers is a lack of water!
Reduction in river flow, owing to abstraction (removal), and
damming, has affected many of our rivers, for example, those
flowing through the Kruger National Park.
INTERCATCHMENT TRANSFER
This involves the movement of water from catchments with good
supplies and low demand, to those where demand is high and supply
poor. There are seven intercatchment transfer schemes in
operation, and a further eight are under construction or
proposed. The largest operational scheme is the Orange-Fish River
scheme where water gravitates from the Orange River at the Gariep
Dam, and is piped through tunnels and canals to the Sundays and
then the Fish Rivers in the eastern Cape. Other examples are the
Tugela-Vaal (operational) and Lesotho Highlands-Vaal (under
construction) schemes. Tentative plans have been put forward to
buy water from neighbouring states, e.g. from the Okavango River
in Botswana and the Zambezi River in Zimbabwe. As yet, little
research has been carried out to establish the ecological
consequences of intercatchment transfer.
WATER POLLUTION
Industrial and agricultural pollutants common in South Africa
are: agricultural fertilizers, silt, toxic metals, litter, hot
water, and pesticides. However, some of the most common
pollutants come from urban waste water, particularly from
informal settlements which lack sewage and water purification
facilities. The resulting pollution contributes to serious health
problems. For example, typhoid, cholera and gastroenteritis are
transmitted by water contaminated with untreated sewage.
Gastroenteritis is one of three main causes of death in South
African children under the age of five. Between 1980 and 1987,
between half a million and one million South Africans contracted
cholera.
THE FUTURE - RECYCLING AND DESALINATION
Some large industries, such as SASOL and ESKOM, already recycle
water for use in their plants. Regional water suppliers also
recycle limited amounts of water, e.g. water supplied by the Rand
Water Board contains less than 2% recycled water, and this is
likely to increase as demand increases.
Desalination, currently thought to be too costly and thus not
practised in South Africa, is a likely option as we come to
realise the true value of water.
DID YOU KNOW?
* Most of South Africa's water is used for irrigation, and
for the vast majority of farmers water is free!
* Of the 4,5 million people in the Umgeni River catchment,
2,5 million have no direct access to potable water.
WHAT YOU CAN DO
* The quality and quantity of water in our rivers, lakes and
dams is dependant on river catchment management. Work
towards a local catchment management project in your area.
Share-Net (address below), the INR (address below), and your
regional agricultural extension officer are able to assist with
aspects of catchment management.
* Save water by placing a brick (sealed in a plastic bag) in
the cistern (water tank) of flush toilets to reduce the
amount of water used; shower rather than bath - baths use
five to ten times more water than a shower; and never wash
under a running tap.
* Collect rainwater from the roof for gardening. Grow plants
indigenous to your area as they usually need relatively little
water. Water at night and mulch the soil around plants to reduce
evaporation of water.
* Report water pollution to the Department of Water Affairs anf
Forestry, address below.
* Never dump used motor oil onto the ground or into drains.
Service stations collect used oil.
* Use the theme of water for school, wildlife club or
university projects. Share-Net (address below) supplies a
range of resources, including water test-kits and regional
contacts to support water projects.
* "The biology and conservation of South Africa's Waters"
(details below) has a very useful chapter titled "What you
can do".
FURTHER READING
THE BIOLOGY OF CONSERVATION OF SOUTH AFRICA'S VANISHING WATERS.
B.R. Davies and J. Day. Wildlife Society, 1986.
ENVIRONMENTAL MANAGEMENT IN SOUTH AFRICA.
R. Fuggle and M. Rabie. Juta, Cape Town, 1992.
MANAGEMENT OF THE WATER RESOURCES OF THE REPUBLIC OF SOUTH
AFRICA.
Department of Water Affairs and Forestry, Pretoria, 1986.
All books are available from Russel Friedman Books, PO Box 73,
Halfway House 1685. Tel. 011-7022300/1.
Enviro Facts "River Catchments", "Wetlands", "Estuaries",
"Pollution" and "Human numbers". Available from Share-Net,
address below.
USEFUL ADDRESSES
Department of Water Affairs and Forestry.
P/Bag X313, Pretoria 0001. Tel. 012-2999111.
The Institute of Natural Resources.
PO Box 375, Pietermaritzburg, 3200. Tel. 0331-68317.
The Environmentally Friendly Trading Company (Pty) Ltd.
P/Bag 2, Hout Bay 7872, South Africa. Tel. 021-790 2898. Supply
a range of water saving devices, ask for catalogue.
Project WATER.
Umgeni Water, PO Box 9, Pietermaritzburg, 3200. Tel. 0331-454365.
Stellenbosch Water Awareness Project (SWAP).
University of Stellenbosch, Stellenbosch, 7600. Tel.
02231-779111.
Cape River Day Group.
Wildlife Society, PO Box 30145, Tokai, 7966. Tel. 021-7011397.
Share-Net.
PO Box 394, Howick, 3290. Tel. 0332-303931
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