Assessing the Endorheic Character of Groenvlei Using Four Independent Hydrogeological Tools

It has been claimed that Groenvlei, a shallow lacustrine wetland on the southern Cape coast of South Africa, is endorheic. This characterisation was based solely on the inward sloping topography immediately surrounding the wetland and an absence of any surface water outflow. However, four independent hydrogeological tools were used to confirm that water discharges from the wetland into the aquifer along its southern banks, thus invalidating the endorheic characterisation. These tools included contouring of groundwater levels, interpretation of the hydrochemical character of groundwater, electrical conductivity depth profiling and a comparison of natural environmental isotopes in surface and groundwater. This case study supports the need for an integrated approach when characterising and assessing water bodies.