Hydrogeology of the Sterkfontein Cave System, Cradle of Humankind, South Africa

A significant rise in water levels within the Sterkfontein Cave system, reaching nearly 3 meters over two years starting from late-2009, has been linked to acidic and sulfate-rich mine water drainage from the nearby West Rand Goldfield. This phenomenon, observed since early-2010, posed potential threats to the UNESCO-listed fossil site's integrity. Through a comprehensive analysis of historical and recent potentiometric data, alongside hydrogeological and hydrochemical information, researchers have proposed that the cave system's maximum water level is constrained to approximately 1440 meters above mean sea level. The study also revealed notable increases in electrical conductivity (32%) and sulfate concentration (178%) in cave water compared to pre-2010 levels. While these changes indicate a distinct mine water impact, the magnitude of this impact on cave water chemistry is less pronounced than that observed in ambient karst groundwater, such as Zwartkrans Spring water. This research underscores the importance of continued monitoring and vigilance across various disciplines to understand the dynamic response of the water resources environment to hydrological and hydrogeological drivers, thereby informing the future hydroenvironmental management of Sterkfontein Cave and other nearby fossil sites.

Hobbs, P., & de Meillon, N. (2017). Hydrogeology of the Sterkfontein Cave System, Cradle of Humankind, South Africa. South African Journal of Geology, 120(3), 403–420. https://doi.org/10.25131/gssajg.120.3.403