Estuaries are silting up, inland
wetlands are disappearing, some perennial rivers are
drying up, and rivers, lakes and dams are polluted!
Water bodies in southern Africa clearly suffer from
many problems - all of which are linked to the way in
which the catchment area is used.
WHAT IS THE RIVER CATCHMENT
The river catchment, or drainage basin, is all the
land from the mountain to to the seashore, drained by
a single river and its tributaries.
Catchment areas vary greatly in
size - a big river may have a catchment area of
several thousand square kilometres, whereas a smaller
tributary will have a catchment area of only a few
Catchments are separated from each
other by watersheds. The characteristics of any river
(physical, chemical, biological) are determined by
the nature of the catchment and the activities , both
human and natural, that take place in it.
THE IMPORTANCE OF PLANTS
In catchments which have not been cultivated or
developed, the ground cover or vegetation is still in
place. Ground cover is important for the following
* Plants slow down water as is
flows over the land (runoff) allowing much of the
rain to soak into the ground and replenish pools of
underground water. Water seeps from these aquafers
into rivers which are therefore usually perennial
(flow throughout the year).
* Plants prevent soil erosion as
their root hold soil in position, preventing it from
being washed away. IN addition plants break the
impact of a raindrop before it hits the soil, thus
reducing its erosive potential. Rivers running
through an undisturbed catchment are clean, erosion
is slow, and limited to periods of very high
* Vegetation in wetlands and on the
banks of rivers is of particular importance. The
roots of the reeds, sedges, trees, shrubs and grasses
growing in wetlands and next to rivers bind the soil
of the riverbank and prevent erosion whilst cleaning
the water and regulating its flow.
Where plant cover in river catchments has been
disturbed by farming, industry and settlements, soil
erosion increases. In addition, without plants,
runoff increases and the supply of water to aquafers
is reduced because less water soaks into the ground.
Consequently rivers do not have a continuous supply
of water from the aquafers and flow only in the rainy
season. Much of the deposition of silt into estuaries
results from erosion of riverbanks. When riverbank
vegetation is remove, the banks are at the mercy of
the erosive forces of flood waters which scour away
the riverbank allowing the adjacent slope to
A catchment conservation programme should include:
* protection of wetlands such as
vleis and marshes;
* sound conservation practices on
agricultural and forestry lands, eg. all ploughing
and planting should be on the contour; riverbank
vegetation should not be disturbed; lands should be
* prevention of water pollution
from informal settlements, industry or agriculture;
* protection of riverbank
COORDINATING LOCAL ACTION
A catchment is ideally suited to coordinated planning
and management, requiring cooperation between the
many land owners and residents in the catchment. A
first step in encouraging collective action is the
formation of a catchment management committee, with
representatives of all major land users (eg. farmers,
municipal and government officials), which is guided
by regional planners. This management committee
should survey the catchment, and investigate with
specialists the best methods of controlling problems.
It is important that all people in
the catchment are involved in each stage of the
conservation programme, from planning to execution,
as they will be responsible for its success or
failure. Catchment management committees, which may
be private, provincial or national, are active in
both rural and urban areas, eg. Umgeni Water in
KwaZulu/Natal and the Braamfontein Spruit Trust in
WHAT YOU CAN DO
* Alert your local land use authority to misuse of a catchment.
* Start a catchment conservation
project for a river in your area.
* Take part in the "Rivers and
Ridges" competition run by the Wildlife Society
* Read "The Biology and
Conservation of South Africa's Vanishing Waters"
(see below) which includes a very useful chapter
entitled "What you can do."
THE BIOLOGY AND
CONSERVATION OF SOUTH AFRICA'S VANISHING WATERS.
B.R.Davies and J.A.Day. CEMS, University of Cape Town
and the Wildlife Society of Southern Africa, 1986.
INDIGENOUS AFFORESTATION OF
DEGRADED WATER COURSES. Wildlife Management
Technical Guide, Natal Parks Board, 1990.
MANAGING THE WATER
RESOURCES OF SOUTH AFRICA. Dept. Water
All books are available from Russel
Friedman Books, PO Box 73, Halfway House, 1685. Tel.
"Precious Water", "Wetlands",
Regional offices of the Dept. of
Local nature conservation
Dept. Environment Affairs
anf Tourism. P/Bag X447, Pretoria, 0001.
Tel. 012-310 3425.
Wildlife Society of
Southern Africa. Head Office, PO box 44344,
Linden, 2104. Tel. 011-486 3294/5 or 0938.
Wildlife Society, PO Box 394, Howick, 3290. Tel.
0332-303931. Produces resource materials.
Project W.A.T.E.R. (Water
Awareness Through Educational Response.) PO
Box 9, Pietermaritzburg, 3200. Tel. 0331-454365.