coaltech upper olifants river catchment wetland inventory ...

3.6.3 Agriculture
3.6.3.1 Cultivation
One of the greatest threats to wetlands is commercial dryland farming. The cultivated areas
are normally abutting or adjacent to wetlands in the catchment. Many of the midslope seeps
have been drained and are currently under cultivation for the production of maize, as well as,
potatoes, beans, lucerne and soybeans. Pesticides and herbicides used during cultivation
can have a large negative impact on the local fauna and flora, and therefore, the wetlands.
Some of the wetlands are harvested for winter fodder and others are cultivated for grazing
grasses (Palmer et al 2002). The impacts on the wetlands are, therefore both direct and
indirect.
Changes in the runoff patterns, infiltration rate of rain and increased soil erosion are caused
by mismanagement practices and contribute to the degradation of rivers and wetlands. The
additional sediment from the exposed cultivated fields also contribute to increased sediment
load in the rivers. The increased sediment leads to changes in the riverbed and therefore, a
loss in habitat for some freshwater species. The extraction of water for cultivation purposes
results in a decrease in stream flow and changes in the water temperature and chemical
properties. Structures associated with irrigation activities, including channels, pumps and
weirs, also has an impact on the rivers and wetlands (Myburgh 1999).
3.6.3.2 Livestock
Livestock are often moved to grassland containing wetlands, especially during winter, for
additional fodder. Overgrazing and trampling by the cattle can have a large negative impact
on the wetland (Palmer et al 2002, Reeves & Champion 2004).
Wetland Database for UORC - 48 -