Mpumalanga and KZN
© 2014 - Eastern Wetland Rehabilitation
FAQ
A wetland is wet land (i.e. land which is wet)! But not all wet land results in a wetland. Why is this
so? A wetland is found where the land is wet enough (i.e. saturated or flooded) for long enough to
be unfavourable to most plants but are favourable to plants adapted to anaerobic soil conditions.
As soil becomes increasingly wet, the water starts to, fill the space; between the soil particles.
When all the spaces are filled with water the soil is said to be saturated. In areas which are not
wetlands, water drains away quickly and the soil does not remain saturated. However, in wetlands
the water persists or drains away very slowly and the soil remains saturated or flooded for long
periods. Soil in these conditions is said to be waterlogged. Depending on factors such as
temperature, it usually takes a week or so for the plant roots and other living organisms in the soil
to use up the oxygen, causing anaerobic conditions to develop in the waterlogged soil. (Mondi
Wetlands Project)
What are the benefits of Wetlands?
•
Wetlands keep our water clean:
Wetlands are natural filters, helping to purify water by trapping pollutants (they do this by removing the
sediment, excess nutrients [most importantly nitrogen and phosphorus] heavy metals, disease-causing
bacteria and viruses and synthesised organic pollutants such as pesticides). The water leaving a wetland
is often purer than the water, which enters the wetland.
•
Wetlands are able to purify water effectively because:
o
they slow down the flow of water (see flood reduction and streamflow regulation) causing sediment
carried in the water to be deposited in the wetland. This also results in the trapping of other pollutants
(e.g. phosphorus) which are attached to soil particles;
o
surface water is spread out over a wide area, making it easier for chemical interactions between soil and
water;
o
there are many different chemical processes taking place in wetlands that remove pollutants from the
water. For example, wetlands provide a suitable place for denitrification because anaerobic and aerobic
soil zones are found close together. Denitrification is important because it converts nitrates, which could
potentially pollute the water, to atmospheric nitrogen which is not a pollution hazard;
o
some pollutants such as nitrates (NO2) are utilised by the rapidly growing wetland plants;
o
the abundant organic matter in wetland soils provides suitable surfaces for trapping certain pollutants
such as heavy metals; andwetland micro-organisms help decompose man-made organic pollutants
such as pesticides.
•
School of Environmental Sciences at the University of KZN (UKZN)
Website
•
Coastal and Environmental Services
Website
•
Rhodes University
Website
•
Wildlife and Environment Society of South Africa
Website
It generally depends on many factors, some of which are:
•
Size of the catchment
•
Function or Purpose of the wetland
•
Area and Location (influenced by environmental need)
•
Availability of Aggregate (access and availability of materials and resources)
•
The cost of the remedial structure (size and type)
