CHAPTER FOUR
4.4. ECOLOGICAL ANALYSIS
4.4.1. Water Systems
The Raapenberg and Pallotti wetlands are remainders of the formerly extensive wetland system that occurred originally along the Black River. They are important for the health of the river and should be well managed and maintained. In addition, the site plays an important role in the reduction of flooding. Unfortunately, both the Liesbeek and Black Rivers are not in good states. The Black River has been polluted so much that it is unsuitable for contact with neither human nor wildlife.
Figure 4.4 shows the TRUP hydrological systems on a site scale. The two rivers on the site confluence towards the north and form part of the Salt River Catchment Area.
61 Figure 4.4: TRUP Hydrological Systems.
Source :Towards More Integrated Human- Nature Relationships (Blatch, 2016)
Respondents agreed with the idea that water plays a crucial role for natural ecosystems, and that water is absolutely essential for TRUP. However, many respondents spoke about the high degree of pollution in the water as a challenge and liability for an ecology. The need for restoration was expressed throughout all the interview transcripts. For example, respondent 1 explained, “The rivers need to be rehabilitated and restored to its best state to achieve its full potential as a natural system. Much work needs to be done to catch pollution before it enters the rivers.”
Most of the time, the rivers are contaminated along their courses; the Black River pollution is caused by urban development and industrial waste disposal. The drainage also runs through informal settlements, which lacks infrastructure to dispose of wastewater and therefore negatively impacts on water quality of the river. The river also passes through the Cape Town industrial areas and is thus made liable to waste disposal, negatively affecting the flora and fauna. The wetlands along the rivers are therefore poor in quality and in need of rehabilitation and better management.
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❖ Liesbeek River
The Liesbeek River originates from the top of Table Mountain and flows through Kirstenbosch Botanical Gardens. Below the gardens, the river flows through the predominantly wealthy residential areas of Newlands, Rondebosch, Mowbray, and
Observatory. Main sections of the lower parts of the river have been made into canals and riverbeds made to stand with gabion structures. Some sewage pump stations are located along the Liesbeek River (Faragher, 2014; MAA & ARCON, 2016)
The Liesbeek River experienced problems relating to pollution, with dog faeces and fertilizer runoff being key reasons for the low quality of water, in particular towards the more slower flowing floodplain of the Observatory area. There have been efforts towards curbing this problem, through community-based organisations such as the “Friends of the Liesbeek River”. This organisation aims to create an awareness of the importance of the Liesbeek as a green corridor in an urban setting and their work includes the rehabilitation, enhancement, and conservation of the river and its environs. Other challenges include the poor coordination, which has been said to cause the inadequate use of resources as well as the annual flooding of the River Club area due to inappropriate developments (WCG, n.d.)
Figure 4.5: Photo of Canalised Liesbeek River.
Source: Author, 2019
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❖ Black river
The Black River is an artificial river which was created for draining of the Cape Flats wetlands and the management of stormwater flowing from predominantly low-income residential township developments for non-white residents during the apartheid era. The Vyge and Elsieskraal rivers joined to the Black River in the Athlone and Pinelands areas and all three rivers are part of the Salt River catchment area.
These river functions also as disposal canals for treated sewerage originating from works at the Borcherts Quarry (at the Airport) and the Athlone Quarry. The watershed releases its waters into Table Bay through the Salt River channel and is responsible for the pollution of the system because of various settlements in the watershed, waste, overflow of sewage and illegal discharges (WPI, 2011)
Furthermore, there are plugs and malfunctions in sewage systems and nutrients from the wastewater treatment facilities of Athlone Quarry and Borcherts. Farming in the upper Elsieskraal River increases nutrient levels and spurs weed growth, while topsoil fertilizes riverbeds, further obstructing flow. The rise of sea level is a constant problem in the lower watershed, leading to an increase in the likelihood of winter flooding. Without a doubt, the poor coordination and management of the river is a barrier to the proper maintenance of the river (Blue Science, 2016).
Figure 4.6: Black River
Source: (Worcester Polytechnic Institute, 2011)
For development to interact positively on TRUP site, the rivers will need to be rehabilitated.
Especially the Black River, which is unusable by the communities as human contact with
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the river can cause serious health problems. By the de-canalisation, elimination of pollutants and alien plant species from the rivers, the biodiversity, wetlands, and natural resources of the two rivers should be restored to a natural and healthier state.
The rivers hold great potential and opportunities to rethink the relationships between human and nature in terms of protecting and enhancing natural and human systems. It is important to restore the natural assets, balance development needs and ecological sensitivity in order to ensure that development is not at the expense of the natural environment.
The Liesbeek and Black rivers are two interconnected, but different watercourse, in that the first is a natural stream, while the later functions predominantly as a stormwater
channel, the site’s topography and nearness to a densely populated urban areas make the site valuable and one of significant interest. Unfortunately, the water quality and amenity value of the Black river in particular is compromised by pollution through sewage and street refuse (MAA & ARCON, 2016).
Figure 4.7 illustrates the decline in biodiversity and natural resources in the city of Cape Town since its development.
Figure 4.7: Decreasing of biodiversity in the city of Cape Town.
Source: City of Cape Town, 2018
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The loss of biodiversity, due to urban development, is rampant in Cape Town. The TRUP site has a crucial role in the development of natural resources and the protection of biodiversity as it forms part of a green open space corridor network, connected by the city’s river systems, which cross the metropolitan area.