Kuils River Series: Part 4
Development and Sand dunes

by Nikiwe Solomon

In the earlier blogs of this series, I focused on the cheapening of nature – a problem that has occurred over centuries in the Cape.  The effects of this cheapening were made painfully visible during field work I conducted in the Kuils River catchment area in the years immediately before the Covid-19 pandemic.

In addition to the price paid by the community living along the banks of the Kuils River, which I’ve previously discussed, the upgrades of the Kuils River infrastructure and, particularly, of the Zandvliet WWTW, came at a cost to the endangered sand dunes of the False Bay coastline, which have been mined for decades to manufacture the cement that has built South Africa’s colonial and current-day architecture. Cape Town’s coastal line is made up of rocky shores separated by small beaches and long sandy coasts. Many of the sand dunes are considered migratory due to the often forceful seasonal winds that influence the sand deposits and erosion of the summer months (particularly from January to March), and the strong gale force winds of the wet winter months (May to August). Prior to urban development, the mobile coastal dune systems were extensive, but the dunes have been transformed and compromised over the last few centuries, especially in the last 80 years, endangering plant and animal life unique to the Cape coastal region.

Source: Nomnom

All the surviving sand dunes in Cape Town, including those that are degraded and threatened, form essential buffers against weather elements that affect not only human-made infrastructure (e.g. buildings and roads), but also rivers, wetlands and aquifers around the city. The dune plumes that extend up to 15 km inland along the False Bay coast, where the lower section of the Kuils River flows and the Driftsands Nature Reserve is located, were formed over millennia, a result of intense winds causing calcareous and, to a lesser extent, barchanoid dunes to form. As these dunes migrate inland, they become stabilised by vegetation. However, due to the boom in infrastructure development over the last few decades, these mineral-rich dunes have been extensively depleted, leaving a fraction of what was previously there along the coast. Some dunes have only survived because of their location in protected areas such as the Driftsands Nature reserve. The role of these dunes as essential ‘green infrastructure’ has been underplayed or largely ignored, perhaps due to the influence of the multi-billion-rand construction industry. Their mining has been largely unregulated and, according to the CoCT’s own report (2015), few dune-management plans are in place due to the coastal management portfolio being ‘historically neglected and under-resourced, often to the cost of the City and its ratepayers’.

In addition to protecting human-made and natural landscapes from surging storms, our coastal dunes provide a habitat for a host of multi-species communities and regulate environmental and weather conditions, providing vital green spaces in an urban jungle. The exploitation of these dunes without active management intervention has resulted in fewer and fewer natural dunes. While the landscape is changed by more layers of concrete in the name of ‘development’ and ‘upgrades’, the marine environment and climate conditions function as they always have: sand is naturally deposited along the coast; strong seasonal winds blow the sand inland, changing the expected profile of the sand dunes; copious amounts of sand are deposited on roads and buildings; and the changed shape of the dunes makes them more susceptible to erosion, so the vegetation that usually stabilises the dunes can no longer establish itself. 

Image 3.3: Location of sand mining sites in close proximity to the Zandvliet WWTW. (Source: Google Earth 2023)

In the image above, the growth of the mining area behind the Zandvliet WWTW can be seen expanding towards the sea. This places the WWTW, a billion-rand investment, at considerable risk in the coming years. Both the City of Cape Town Coastal Management Report (2015) and a report generated by the CCT’s Environmental Management, Coastal Management Branch (2017), which have since been ignored, indicated that dunes that are stripped of vegetation cover have their natural processes of trapping and retaining windblown sand compromised. When the sand dunes can no longer trap and retain sand, it affects their advancement and retreat, compromising their ability to act as effective coastal barriers. Should the sea levels continue to rise as anticipated, seawater will eventually breach what remains of the dunes, making the infrastructure susceptible to flooding and causing the salinisation of the shallow coastal Cape Flats Aquifer (CFA), an acutely important source of water security for both the City and its surrounding farmlands. 

The 2020 flooding of the Sandvlei community, when the Kuils and Eerste river banks broke after heavy winter rains, also indicates a real risk to this project. The WWTW could be flooded by seawater on one side and freshwater on the other. The rise in sea level is also likely to affect the freshwater that flows in the Kuils and Eerste Rivers close to the rapidly degrading sand dunes, compromising the soil’s productivity for local farming communities and for one of the last remaining farmlands within the Cape Town metropole, the Philippi Horticultural Area (PHA), which relies on CFA groundwater for irrigation. 

Location of the Cape Flats Aquifer. (Source: Giljam, 2002)

The reliance on concrete to upgrade the urban environment destroys its relationship to dunes, and ignores the vital flows of materials, energy and nutrients that make up urban ecosystems, and facilitate urban metabolisms. This understanding of how to use cement also overshadows the lived experience of communities like those at Sandvlei, which have suffered most from failing infrastructure, because cement is not impervious to time and needs regular maintenance. In addition, the upgrade of the WWTW, which is costing billions of Rands (in loans that have to be paid off in the future), is premised on a fixed population and a fixed understanding of urban metabolisms. What will happen in another 10 years, when the population of Cape Town has significantly increased again? Will another loan be taken up to upgrade failing or overwhelmed infrastructure? Given the many unknowns of climate change, what will happen in 20, 50, and 100 years?

As this blog series has suggested, there is no singular way to think about, or approach, the multiple challenges attending the management of river catchment areas that have seen rapid and continuous human encroachment over centuries. Only a holistic and multi-faceted viewpoint, that is able to account for the politically-induced errors of the past, alleviate the pressures of the present, and anticipate the challenges of the future, has any hope of providing adequate management for the Kuils River catchment area. 

This means every citizen of Cape Town has to stay vigilant, learn more about our rivers, and be attentive to their health. We have to ask those we elect how they know their decisions are the best ones for our rivers and their surroundings. We also have to keep doing our part to ensure that our political leaders and City managers know we’re aware of, and care about our urban rivers, and more broadly, our wetlands city with its newly-recognised Ramsar Wetland City status. We have to keep up steady pressure for the right actions to be taken at the right time, and show up for our rivers by joining in whatever water movements are forming around their protection.