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| RHP |
South African
River Health Programme
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State of the Rivers Report
uMngeni River and Neighbouring Rivers and Streams
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HOW TO READ THIS REPORT
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The river health information for the uMngeni and neighbouring rivers was organised into seven resources units for reporting purposes.
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A resource unit is a sub-catchment of the larger study area that was chosen as a unit of reporting partly because it is a sensible goegraphic unit for river management, but also because people can relate to sub-catchments (often associated with dams) much better thatn to ecoregions, which are used by ecologists and managers to make ecological assessments. The uMngeni catchment was divided into six resource units, with several corresponding to the drainage areas of the major dams, while the uMlazi catchment forms a resource unit on its own. Resource unit nformation pages are followed by a summary and overviews of river issues of particular interest in these catchments.
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Each page that deals with a particular resource unit shows the same type of information, i.e.an introduction to the resource unit, the present health, driver of river health, a summary of goods and services derived from the river system and the key management actions that are needed to improve river health in the particular resource unit. Topics of particular interest in any one resource unit are also highlighted and these may deal with drivers, impacts, river goods and services or management reponses.
Information was chosen deliberately. National guidelines require that we report on the present health, the drivers of present health and the actions we plan to perform in order to improve river health. But, the report also addresses river goods and services so that we are able to link the types of benefits we derive from rivers with changes to their ecological state, and the way in which we manage these.
The present health is a measure of the current ecological state of the river and it reflects the response of the river to all the natural as well as human induced disturbances that have taken place prior to the survey. In this report, different aspects of the current state of the river (condition of fish population, habitat quality, etc.) are shown by means of icons and these are based on river health data collected over the last decade.
Pressure and driving forces. Pressures are those fators that have an impact on the health of the river, while driving forces refer to human activities which create these pressures. Knowing about the driving forces and pressures on a river provides insight into why the river is in its present health and in turn, help us to decide what actions may improve river health.
Goods and services provided by the rivers refer to the river ecosystem processes and products that sustain and support human life. People benefit from the harvest, use and trade of these goods and services and they form a familiar part of our economy. Some of the goods and services that we get from rivers are water for drinking, cooking, washing, power generation, manufacturing and crop irrigation, food (for example fish and crabs from the river and fruits from the riparian zone), a surface for recreation (and associated tourism), the dilution and processing of pollutants and the provision of building materials (reeds, wood, staone, sand).
A particular state of the river ecosystem enables us to use a particular range of goods and services provided by the river. The use of goods and services also influences (or drives) the state of the river ecosystems. For example, a factory may use river water as a coolant, but at the same time it may return water to the river with an altered chemistry. This process may affect water quality and make it unsuitable for say, crop irrigation downstream of the factory. Thus, the use of river gooods and services bring costs as well as benefits to different users.
Management actions. These refer to what is currently being done, how people should respond to problems (through changes to management strategies and policy), how to make their response more effective and how to prioritise management actions.
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MIDMAR RESOURCE UNIT
Upstream of Midmar Dam wall and including the uMngeni and Lions rivers, as well as large wetlands at the headwaters.
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ALBERT FALLS AND NAGLE RESOURCE UNIT
Including the uMngeni River from below Midmar Dam to Nagle Dam, including the Karkloof, and iMpolweni tributarties.
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INANDA RESOURCE UNIT
Including the uMngeni River from below Nagle Dam to Inanda and the uMsunduze River below Pietermaritzburg. This unit includes Valley of a Thousand Hills.
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UPPER UMSUNDUZE RESOURCE UNIT
Including the upper reaches of the uMsunduze River.
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PIETERMARITZBURG RESOURCE UNIT
With the uMsunduze River flowing through Pietermaritzburg.
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UMLAZI RESOURCE UNIT
From the Midland Foothills to the near Durban airport. This resource unit includes the Sterkspruit and Wekeweke tribitaries.
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LOWER UMNGENI AND DURBAN RESOURCE UNIT
Including the uMngeni River along the flat coastal plain, the Blue Lagoon estuary and the uMbilo and uMhlatuzana Rivers.
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