World Water Quality Assessment Use Case Study – Cape Town Aquifers: Deliverable 5 – Summary Report

The Cape Town aquifer use case comprises various aquifers in and around Cape Town that are earmarked for water supply to the city. The Cape Flats aquifer underlying most of the city is highly vulnerable to pollution from land-use activities, including small-scale agriculture and sand mining, and from landfill sites, cemeteries, industrial areas and informal settlements without proper sanitation. This has led to salinization of the groundwater and contamination with nutrients, microbiological and industrial contaminants, hydrocarbons and, possibly, contaminants of emerging concern. Extensive in situ monitoring data, remote-sensing (Earth Observation) data, detailing land use and identifying pollution sources, and vulnerability and flow modelling were used in the assessment. Feeding into stakeholder engagement, groundwater protection zones were proposed as a potential assessment product. The high variability of natural groundwater quality and the lack of historic water quality data had prevented assessments of the current state of deterioration. Nonetheless, the findings can be extrapolated to other urban centres with similar geological settings.