SATURDAY INTERVIEW

ing, the conventional way of capturing water for urban areas, has reached a limit, but that catchment options have not.

The history of dam building – from the Waggenaar reservoir in the City Bowl in 1663 to the Berg River dam in 2007 – revealed a pattern of infrastructure development keeping pace with urbanisation.

“In many ways, dam construction is a proxy for urban growth: the dates (of dams) reflect population growth in Cape Town driven by the influx of settlers post- 1820; preparation for and postwar settlement during and after the South African War of 1899-1903; post First World War settlement after 1918; post Second World War settlement after 1945; and rapid urbanisation from the 1950s onwards.

“With traditional catchment areas exploited, new solutions have to be found to ensure a sustainable freshwater supply to the Greater Cape Town Metropolitan Area.”

Citing the 2nd UN World Water Report, and scholars in the field, Van Wyk writes that in the light of climate change, the unpredictability of weather, the scarcity of freshwater globally and the steady growth of cities an “Integrated Water Resources Management” approach as a way to rethink the sustainability of a resource as indispensable as water.

The conventional approach to water catchment considered only natural features, but, thinking differently about water, “eco-engineering provides at least two opportunities”. Both were predicated on understanding of catchment areas to include every roof and street of the city.

Tapping into the underground water in aquifers was one option. At the present, though, much of the water that might refill aquifers is chan- nelled away – to the sea – as storm water.

In Cape Town’s case, the Cape Flats Aquifer could yield significant quantities of water, but “sustainable management of the aquifer would require eco- engineering solutions where rainfall is not diverted to a storm water system but is carefully managed and treated to recharge it”. Urban sprawl “severely restricts the ability to recharge aquifers even as it increases demand”.

Three strategies were required: “the precipitation

GRAPHIC: SUPPLIED. Every house or building can be part of the catchment area, as this diagram shows.