Alien species Fauna and flora introduced intentionally or by accident from other countries. Not all alien species are invasive. Of the approximately 8 750 plant species introduced into South Africa, only 161 are regarded as invasive and 75 of these require control by law.

Buffer Zone A buffer strip on the outer edge of the riparian zone is required to protect the habitat and the water resource. A minimum of 20 m is required depending on the type of land use, the sensitivity of the habitat and the scarcity of the water resource.

Bedrock Solid immovable rock in the river channel.

Biodiversity The variety and variability among living organisms and the ecological complexes in which they occur. Biodiversity can be organized at various levels, ranging from complete ecosystems to molecules.

Ecological Reserve The quality and quantity of water that is required to protect the aquatic ecosystems of a water resource.

Ecologically sensitive releases Releases from impoundments in terms of water quantity, quality and variability that are designed to maintain a certain state of river health downstream of the impoundment.

Environmental impact assessment (EIA) A process of predicting and evaluating the effects of an action or series of actions on the environment. The conclusions are then used as a tool in planning and decision-making.

Erosion The lowering of the land surface by weathering, corrosion and transportation, under the influence of gravity, wind and running water. Erosion is a natural process but the rate and nature of erosion can be accelerated by human activities.

Floodplain The low land that borders a river, ocean or lake, usually dry, but subject to flooding.

Hybridise To cross-breed.

In-stream Flow Requirement (IFR) The volume and nature of water releases from impoundments to maintain the river in a pre-determined state of health. The objective of an IFR is to manage flow to ensure long-term maintenance and conservation of riparian vegetation and to ensure sustainable resource utilisation. The latter includes the water quantity, in-stream aquatic communities and riparian communities.

Overgrazing The level of livestock grazing that exceeds the land’s ability to support that level of grazing over the long term. Overgrazing leads to degradation of the land.

RAMSAR sites are wetlands of international importance. South Africa has 16 RAMSAR sites, including Nylsvley Nature Reserve and the St. Lucia System. The RAMSAR Convention on wetlands provides a framework for national action and international cooperation for the conservation and wise use of wetlands and their resources.

Red data species Species of plants and animals that are under threat. The red data categorization of species helps to determine their conservation status. The categorisation follows the IUCN guidelines and includes categories such as extinct, endangered, vulnerable and rare.

Riparian zone The area adjacent to a river or water body that forms part of the river ecosystem. The riparian zone plays an essential role in the functioning of the river ecosystem. It is characterised by frequent inundation or sufficient flooding to support vegetation distinct from surrounding area.

Subsistence agriculture A level and type of agricultural practice that supports the basic livelihood of an individual or group of people.

Wetland An area where the soils are periodically or permanently waterlogged. Wetland plants are adapted to tolerate seasonal inundation. Wetlands moderate water flow by acting as sponges during wet periods. Wetlands regulate water quality by slowing down the flow of water, causing suspended matter to settle out or to be absorbed by wetland plants.

Working for Water (WfW) The WfW programme was launched by the national Department of Water and Sanitation to control the alien invasive plant problem, in particular the impacts of these plants on water resources. A combination of methods like manual clearing, chemical control and biological control is used.