Study area with catchments

1.4 The study area

“Today, the Salt River is no more than a canal that receives water from the Liesbeek River and the Black River. Although flow in the canal is still tidal, the once great Salt River Lagoon and its estuary are no more”(Cate Brown and Rembu Magoba, 2009).

The Salt River canal is a drainage canal, that was built in 1950’s to drain the Salt River marsh for urban development and the establishing of the Culemborg rail way yard. The mouth needed to move further north for the expansion of the Cape Town harbour. Today the canal is 2,4km long and has 14 bridges of various depth and heights crossing it. It is the downstream reach of the Salt River catchment, which comprises of the Vygekraal River, Elsieskraal River, Black River, Liesbeek River, Jakkalskraal, Blomvlei River, Kalksteinfontein, Bokmakierie and Kromboom River. The canal meets the Atlantic Ocean in the Table Bay in close proximity of the harbour. As an urban canal, it serves the function of transporting stormwater fast towards the sea. One inspiration for this thesis was the Book “When the Rivers �un �ry - The global water crises and how to solve it”, (Pearce,F. 2018) that I picked up at an airport on my way to a reference week in Weimar. “The rivers had been straightened and the land had been built on so much that there was nowhere for the water to go. However, you raise the levees, a river in flood will find the weakest spot and burst through. Rivers were to be allowed back onto the floodplains, and overspill areas of low-lying land would be set aside to lessen the impact of major floods”(Pearce, 2018). The book explains in drastic and simple ways, how we humans, by understanding how nature works exploited it for our own good, not thinking of our broader communities or generations to come.

“The liquid state is very rare in the universe, water is the only liquid that forms naturally on the earth’s surface” (Rutherford Platt,1971).

The Salt River canal must have been such a project, optimizing the value of the land in terms of development and ignoring natural processes and habitat loses. Draining the wetlands and the salt marsh, changing the outflow to sea and building a sterile canal, that has no connection to its surrounding, but draining the newly created catchment straight out to sea, without riverine processes like groundwater recharge, bed formation, cleaning and pooling of water.

The chosen study area comprises of the “Old” Salt River, that stretches now over three catchments, namely the Diep River catchment, the Salt River catchment and the City catchment. It includes the Zoarvlei wetland area, that is an abandoned meander of the former Salt River and the Old Salt River canal, where the old river mouth was once situated. The Salt River marsh, that is now mostly developed as railway yards and the existing canal are all part of the study area, see illustration 5.

Today the area is turning its back side on all waterbodies and is mostly developed as an industrial area that is affiliated with the container harbour.

Above ground, the land sparkled with water. A lazy river meandered through; tinted the colour of strong tea by the ample nutrients it picked up along on its way to meet the sea. The river’s water was full of fish, and along its shores tiny insects and boisterous amphibians flourished. Overhead, birds swooped low over the water, and their chatter and song cut through the crisp air from before dawn. (Kotze, 2019)