coaltech upper olifants river catchment wetland inventory ...

3.6.6 Industries
Industries can have a large impact on wetlands. The impacts differ between industries, but
some impacts are common to all, e.g. polluted water. In addition, bad practices during the
construction or operational phase can have far reaching impacts on wetlands in the vicinity
or downstream of the industries. It is therefore imperative that sustainable development
takes place and that industries adhere to strict control measures to limit the impacts of the
development on the environment (Adebayo no date, Dugan 2005).
3.6.7 Harvesting of wetland resources
Wetlands are a source of various useful products, including fish, medicinal plants, plants
used for crafts and building sand. The removal of these products is seldom controlled and
this has led to the degradation of some of the wetland systems. Wetlands are an important
source of building sand and the mining of these wetlands for sand has been extensive in the
past. It has often happened that the sand is removed and the wetland is not rehabilitated
afterwards. This degradation of the natural habitat favours the establishment of pioneer, and
alien and invasive species (Palmer et al 2002, Kotze et al 2005).
3.6.8 Infrastructure
The network of roads and railways, with associated infrastructure such as bridges and
culverts, in the catchment is well developed. The structures have a significant impact on the
surface drainage patterns. Wetlands downstream of the roads and railways are drying up,
and new wetlands are forming upstream of the structures. A common feature of road and
railway crossings are that they restrict water flow, thereby causing backflooding upstream
and concentrated flow downstream of the bridges. The result of this is erosion downstream
of the bridges, often with extensive erosion gullies, and associated channel incision. This
reduces the amount and frequency of overtopping occurring during a flood event. Several
wetlands that are historically seasonally wet have therefore dried out to temporary wetness.
The structures also interfere with the normal migration patterns of a number of animals,
including frogs (Palmer et al 2002, Lizamore pers com 2004).
Wetland Database for UORC - 50 -