SuDS for managing surface water in Diepsloot informal settlement, Johannesburg, South Africa

Abstract

Sustainable drainage systems (SuDS) imitate natural water management processes in catchments that have been degraded due to urbanisation. The aim is to reduce the quantity of stormwater runoff and improve water quality. Management of rainwater in the informal settlement of Diepsloot in Johannesburg is compounded by domestic wastewater discharged into the informal lanes. These lanes fall outside the mandate of the City of Johannesburg’s stormwater management system; hence residents need to rely on their own initiatives to address surface-water problems. This preliminary study investigated the introduction of SuDS to enhance existing surface-water interventions, as a low-cost flexible approach. Using action research methods, small-scale interventions were designed, constructed and refined by residents and researchers at two sites close to the Jukskei River. While the primary intention of the research was to reduce standing water in the public areas, water quality testing indicates that the SuDS reduced some pollutants. Nitrate and phosphate concentrations were slightly lowered through the introduction of permeable channels and soakaways, while these interventions had a moderate effect on chemical oxygen demand. The involvement of residents at the two sites was markedly different, reflecting divergent priorities and social dynamics. Spontaneous continuation of the SuDS system at one of the sites indicates successful knowledge and skills exchange. This study was of limited duration with only two sets of water quality tests; therefore, longer term monitoring is strongly advised to be able to give more robust assessment of this type of intervention.

Keywords: SuDS, action research, water quality, informal settlements, Diepsloot