Pathways to water resilient South African cities – from mono-functional to multi-functional stormwater infrastructure

Abstract

In light of rapid population growth and climate-change pressures on water resources, there is an urgent need in many African cities to shift to more resilient, decentralised, nature-based approaches. In response, the City of Cape Town's Water Strategy document proposes various alternative water supply sources. One is Managed Aquifer Recharge (MAR) using the Cape Flats Aquifer (CFA). Overlying the CFA are a significant number of stormwater ponds that were originally designed solely to prevent flooding. These ponds could be retrofitted to infiltrate stormwater run-off, recharging the aquifer and serving a water treatment function using nature-based approaches. Many of these mono-functional ponds are in neighbourhoods that are socio-economically disadvantaged through former apartheid spatial planning. These ponds are frequently litter-filled, used for dumping rubble and, on occasion, occupied with informal housing. It is in this context that the conversion of engineered single-purpose stormwater ponds into multi-functional space is proposed using a demonstration site in Mitchells Plain, Cape Town. The ‘Pathways to water resilient South African cities (PaWS)’ project is a collaboration between the Future Water Institute at the University of Cape Town (UCT) and University of Copenhagen (UCPH), funded through DANIDA. This research is revealing how maximum benefit could be derived from these water management systems by adopting low-cost, easy to install blue-green interventions that rely on nature-based approaches. The findings from the research have relevance across Southern Africa where several large cities have existing stormwater ponds designed for flood control or as passive open green spaces. It offers valuable strategies for how these single-purpose ponds can be transformed into multifunctional blue-green spaces in ways that build resilience while addressing the environmental injustice that is a legacy of South Africa's ‘green apartheid’.