Karst geomorphology and related environmental problems in Southern Africa – a review

Abstract

Globally many valuable karst resources are under severe threat due to anthropogenic activities. This paper presents a review of the geomorphology of karst landforms including caves, sinkholes, etc. in southern Africa. It further presents the environmental threats and challenges faced by these karst landscapes, their genesis and controlling factors, as well as their possible mitigation and remedial measures. The karst landscapes in the region are most abundant in the interior of the sub-continent, whereas coastal karst is sparsely distributed, and is mainly found in the Eastern and Western Cape, and Kwa-Zulu Natal provinces of South Africa, as well as parts of Namibia. The karst of the interior is largely limited to the Proterozoic dolomitic limestone, while coastal karst is formed in the Tertiary coastal limestone and Quaternary calcareous sandstones. The human impacts threatening karst in southern Africa include mining and mineral extraction, construction and development, agricultural activities, climate change, and changes in the local hydrogeology. Anthropogenic impacts have particularly affected the karst landscape of the Gauteng and northern Free State Provinces of South Africa due to groundwater extraction associated with mining. Changes in land use and water management, consequential to development pressures and a variety of climate change scenarios, are the most significant threats currently facing southern African karst terrain. It is argued that sustainable engineering technologies, informed by sound geomorphological research, are necessary to ensure that future development, property, and life on karst terrain are safe from avoidable environmental problems.