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Ekurhuleni View Map This project is active in several quaternary catchments in the Ekurhuleni Metropolitan Municipality in Gauteng. Rehabilitation intervention is implemented in wetlands that drain into the Klip, Kaalspruit, Rietspruit, and Swartspruit rivers. Previous WfWet projects in these catchments focused on Bullfrog Pan and Blesbokspruit.
Increasing urbanisation within the municipality has resulted in a range of development-related impacts on its wetlands. This includes concentrated storm water outflows, roads, pipeline and railway line crossings, infrastructure encroachment, invasive alien plant infestations, channelisation, channel incision, headcut erosion, mining and dumping. These impacts reduce the ability of the wetlands to provide ecosystem services such as water purification and flood attenuation. Water pollution is a major concern, and wetland rehabilitation is considered of high importance for improving water quality.
Wetlands suitable for rehabilitation were identified at Van Riebeeck Park, Kempton Park, near Thembisa north of Ivory Park, north of Carnival City near Kwathema in Brakpan and near Palm Ridge south of Thokoza.
The project provides temporary employment and skills development for 45 people. Its budget for 2008/9 is R2,330,000. Rehabilitation interventions include gabion and concrete structures to de-activate erosion headcuts within the system.
Kwenele Park (Siluma)
In 2007, a badly degraded wetland in the Natalspruit catchment was been transformed into a valuable open space of recreational and survival value for its human, avian and amphibian visitors, thanks to efforts by Ekurhuleni Metro, the Rand Water Foundation, the Gauteng Department of Public Transport, Roads and Works, and WfWet.
Previously called Siluma Park, Kwenele Regional Park is bordered by the suburbs of Katlehong, Voslorus, Thokoza and Siluma View, making it of strong community value. However, until recently the wetland and surrounding open space was considered to be nothing more than an eroded wasteland “belonging to someone else”, which resulted in it being used for uncontrolled dumping and destructive small-scale farming. Insensitive development practices and a badly designed storm water outlet upstream created significant erosion problems that greatly reduced its value as a refuge for urban wildlife and its ability to continue providing beneficial services to nearby communities and downstream users. Because of its importance in the fabric of its urban landscape, the wetland was prioritised for rehabilitation by Ekurhuleni Metro and other stakeholders.
Rehabilitation work began in 2004. Earth plugs and gabion and concrete structures were constructed to block erosion channels, stabilise banks and trap sediment, to ensure the restoration of wetland functioning. The site’s importance to urban wildlife was proven when a large number and range of birds returned to the wetland subsequent to rehabilitation. The project also focused strongly on awareness work in the nearby community and schools.
Riebeeck Park 1 Wetland : The 44 ha wetland is a channeled valley bottom wetland that receives water from the Swartspruit and storm water drains. The wetland drains back into the Swartspruit through the centre of Kempton Park. The Swartspruit in turn drains east into the Rietvlei river, which flows into the Rietvlei Dam, an important source of water for Tshwane Metro. Land use in the catchment is mainly urban (residential, industrial and a golf course) but also includes an area of natural grassland. Because development has resulted in a much larger area of hardened surfaces, water flows into the system at high volumes and speeds, and there are consequently increased flood peaks. Channels in the wetland concentrate stream flow, which results in channel incision and headcuts. This has altered the system’s integrity and functioning, and threatens to destroy the remaining healthy sections of wetland. Pollution enters the system from a range of urban sources, including the Kempton Park Golf Course, residential areas, roads and a range of urban activities. Given the water pollution impacts on the river system, which includes a sewage treatment works downstream of Riebeeck Park, the wetland’s water purification function is considered its most important ecological service. Rehabilitation intervention is designed specifically to address its ability to continue to provide this service. The upstream wetland areas are secured through stabilising headcut erosion and raising the water table within incised drainage channels.
Olifantsfontein Wetland : This is an 18 ha channeled valley bottom wetland that drains directly into Kaalspruit, one of Gauteng’s most polluted rivers. It is linked to the Glen Austin Pan and is fed by seepage and surface water inflow. Land use in its catchment is mainly agriculture, with areas of natural grassland. Although the catchment is largely undeveloped, there are strong impacts in the form of dumping, overgrazing and invasive alien plan infestations. It’s hydrology is modified by historical and current sand and clay mining, both in the wetland and its surrounds, and the wetland itself is impact by earth dam walls that concentrate water flow and cause channel incision and erosion. Headcut erosion and active channel incision are drying out the wetland. A new housing development proposed for around the wetland system will increase storm water flow into the system, which is likely to aggravate the existing erosion. Rehabilitation intervention is focused on stabilising headcut erosion and raising the water table within incised erosion gullies and in the excavated areas. The eroded dam wall will be removed to allow for a more even spread of water across the wetland. There is also a recommendation to fence off the area to prevent livestock from tramping wetland soils and vegetation and to aid in controlling sand mining activities.
Kwathema 3 Wetland : This is a 19 ha unchanneled valley bottom wetland on the Rietspruit and Natalspruit rivers, with a hydrology driven primarily by subsurface water inflows, including an increasing input of storm water run-off from the upstream residential area. Land use in the wetland and its catchment is mainly informal residential, industrial, natural grassland, and an aerodrome. Hardened surfaces in its catchment result in the inflow of high volumes of fast-flowing storm water, and consequently increased flood peaks. Incised gullies drain storm water into it from the high lying catchment areas. A soil embankment in its upper area concentrates water flow and aggravates channel incision, which results in desiccation of part of the wetland. Livestock grazing threatens to cause erosion which threatens wetland functioning and integrity. The wetland also receives a range of pollutants. Rehabilitation intervention involves the removal of the soil embankment to allow for a more even spread of water across the wetland. It is considered necessary to mitigate for flood peaks and the high-energy inflow.
Palm Ridge Wetland : Palm Ridge is a 44 ha unchanneled valley bottom wetland on the Natalspruit. It receives water primarily from subsurface inflow, as well as surface flow from upstream. Groundwater seems to be a major hydrological factor, believed to be entering the system from the underlying dolomitic geology. The wetland has extensive continuous seasonal and permanent zones of wetness, with some parts being highly saturated. Land use in its catchment is residential and agricultural, including livestock grazing. Erosion resulting from past and current agricultural practices has modified the wetland’s hydrology. Headcut erosion threatens a substantial area of the wetland, and there is an influx of sediment and fertilizer run-off. Rehabilitation intervention focuses on stabilising headcut erosion and raising the water level within the incised portions of the drainage furrows. Contacts
For more detailed information such as project implementation plans and progress reports, please visit www.thelapa.com, click on Working for Wetlands and enter view for both username and password.
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