Walking the Watershed: stepping along the continental water divide in Johannesburg

On 28 September 2022 a group of participants at the Water Institute of South African Annual Conference walked along the continental watershed that runs through the centre of Johannesburg. Organised by Hannelie Coetzee, an independent artist and innovator, the Water Research Commission and the GCRO the tour used walking and talking as vehicles for immersing the participants in the hydrology and political geography of aspects of water in Johannesburg. This watershed, which has been precisely delineated using fine-scale digital elevation data, divides rivers that drain into the Indian Ocean from those that flow to the Atlantic. Tracing this line on allows us to consider how water moves through the landscape and the administrative boundaries we superimpose over this. It will also bring into focus the implications of locating a major urban complex on the watershed, resulting in Johannesburg’s dependence on water transferred from distant major rivers and another country.

The tour started at the new Ingwe Park in Braamfontein the group looked at the presence of magnetic rock to discuss the importance of gold and why Johannesburg is located where it is (at the top of the watershed) as opposed to along a major river, and what this means for management of water in the city and downstream. The tour then followed the link of the watershed east across Braamfontein, stopping at Constitution Hill before continuing through the densely populated area of Hillbrow. A number of stops along the route were designed to discuss different aspects of urban water. The tour ended at the top of Ponte Tower looking across the City. To the north rivers drain to the Crocodile-West Marico catchment and south to the Upper Vaal Catchment.