The West Coast in the Western Cape of South Africa is a water-scarce area. With pressure from population and industrial growth, recurring droughts and climate change, there is increasing urgency in the West Coast to protect groundwater resources. Saldanha Bay is dependent on groundwater as part of its bulk water supply system. Where the natural groundwater recharge is no longer sufficient to meet the growing groundwater needs, practices such as Managed Aquifer Recharge (MAR) can be used to ensure the sustainability of these groundwater resources.
This study aims to identify areas within the Saldanha Bay Local Municipality suitable for Managed Aquifer Recharge to maximize the water available during periods of limited surface water supply. As such, the MAR study site identification requires a comprehensive geohydrological assessment of the Saldanha Bay aquifer. This includes an understanding of the quality and quantity of the source water available for recharge, the aquifer structure and hydraulic properties, the space available to store water, and the compatibility of the recharged water with the groundwater.
MAR research methods included Time Domain Electromagnetic (TDEM) airborne geophysical surveys, infiltration tests, pumping tests and hydrochemical analysis. TDEM surveys provided clarity on the various aquifer geological properties. Infiltration and pumping tests shed light on the horizontal and vertical hydraulic properties of the aquifer. PhreeqC modelling outputs helped predict the outcome of the mixing between groundwater and potential MAR water resources.
Geological features were delineated through TDEM surveys and inferred five suitable MAR sites where clay layers were missing. Infiltration and pumping tests showed that Langebaan Road is better suited to borehole injection, whereas Hopefield has the benefit of infiltration MAR techniques as an additional option. PhreeqC outputs exhibit that both pipeline and Berg River water show promising results as potential source water resources for MAR as compared to other resources.