In this paper, we use a decolonial lens to reflect on a place-based transdisciplinary Nature-based Solutions (NbS) research project that focussed on the multifunctional retrofitting of a stormwater detention pond through coproduction in Mitchells’ Plain, Cape Town. We find that stormwater ponds represent promising yet contested leverage points for coproducing NbS towards water resilience in Cape Town. We also find that ‘scaling deep at the margin’ is an important initial condition for experimenting with NbS in contexts of deep difference. Here resistance and desire are central dynamics that may help rework the unjust power asymmetries in the post-apartheid city. Researchers need not foreclose the possibilities of failure in transdisciplinary NbS experiments when resistance is encountered, instead they should explore the generative insights that may result from failure. We conclude that sustainability transitions in the Global South may be more productively understood as contested, seldom-complete endeavours in which justice remains the goal.

A stormwater detention pond in a low-income residential area in Cape Town, South Africa, was retrofitted to enhance its infiltration capacity and support, among other things, Managed Aquifer Recharge (MAR) in the Cape Flats Aquifer (CFA). Continuous field monitoring was not feasible owing to theft and vandalism risks, leading to the development of a calibrated and validated hydrological model. This model, which integrated the surface and subsurface interactions, evaluated the pond’s performance under six scenarios. The scenarios included: pre- and post-retrofit (Scenarios 1 and 2); potential MAR coupled with the planned abstraction and additional MAR by the City of Cape Town in the CFA (Scenario 3); the impact of an increased infiltration area coupled with a lowered water table (Scenario 4); and climate change impacts on MAR (Scenarios 5 and 6). The study found that retrofitting increased recharge by 118% even with a high water table—i.e., 1.2 m below ground level—(Scenario 2). Scenario 3 indicated groundwater abstraction could increase MAR by up to 290% as the water table is lowered. These findings demonstrate the potential hydrological benefits of retrofitted ponds in enhancing MAR while maintaining their detention functions.

The City of Cape Town (CoCT), South Africa is committed to becoming a water sensitive city (WSC) as laid out in the Water Strategy (CoCT 2019). Becoming a WSC includes expanding the functionality o...