| dc.description.abstract | The discovery of gold and diamonds, followed by coal during the late 19th century changed the entire economic structure of the Southern African region (Booyens, 2008:17; Van Eeden et al., 2009; Jurad, et al., 2010:78–79; Winde & Stoch, 2010; Peatfield, 2003:355). Despite the many positive developments brought about by gold mining, there are also a number negative aspects associated with mining. These include environmental degradation (specifically water pollution and the dewatering of dolomitic compartments which is strongly associated with sinkholes) as well as health threats for local inhabitants (such radon emission, dust and exposure to radiation).
Mining in the Far West Rand, wherein the study area falls under, occurs on dolomitic land (Buttrick & Van Schalkwyk, 1998; Swart et al., 2003; Watermeyer, 2001; Ngcobo, 2006). Dolomite can be defined as a soluble carbonated bedrock. Constant exposure of dolomite to rainwater together with negative impacts associated with human activities (such as ground water extraction, leakage from water pipes and sewerage systems) dissolve the rock over time because these substances penetrate through joints of the rock to form openings beneath the surface – which may result in sinkholes (Swart et al., 2003; Kirsten et al., 2006; Zhou, 1997:50; Van Eeden et al., 2007). Sinkholes are likely to occur without warning, although cracks in walls are often early signs of danger. They are either caused by the hollowing out or formation of a void below the earth’s surface as a consequence of normal geological processes or they may have anthropogenic causes. Anthropogenic causes such as the construction of roads, township development and associated services, groundwater extraction and groundwater recharge may also give rise to the formation of sinkholes (Haarhof, 2011; Buttrick & Van Schalkwyk, 1998; Ngcobo, 2006; Watermeyer et al., 2001; Watermeyer et al., 2002; Swart et al., 2003; Gutierrez, 2006; Buttrick et al., 2011). The Merafong Local Municipality (MLM) is located within the West Rand District Municipality (WRDM), in the Gauteng province of South Africa. Its boundaries enclose some of the richest gold mines such as Western Deep Levels, Driefontein West and East, Blyvooruitzicht and Doornfontein (Van Eeden, 2006:417). In spite of the relative wealth and economic activities generated by mines, a number of serious environmental issues such as sinkholes in this area started to emerge at an alarming rate after gold mines have been granted permission by the government to drain dolomitic compartments (Van Eeden, 1997; Van Eeden, 2003; Swart et al., 2003; Coetzee et al., 2004).
The occurrence of sinkholes in the MLM is historically associated with loss of life and damage to infrastructure. Some of the catastrophic events associated with the dewatering of dolomitic aquifers within the Merafong area include the following: • Sinking of the West Driefontein crushing plant as well as the business sector of the Carletonville Township (known as Khutsong) into sinkholes; • Evacuation of inhabitants of the farm Bank due to unstable surfaces caused by ground movement; • The death of a family of five at Blyvooruitzicht due to a sinkhole; • Drying up of boreholes used for farming activities as well as cracking walls of local houses and the deterioration of infrastructure (Winde & Stoch, 2010; Van Eeden et al., 2003; Van Eeden, 2006; Ngcobo, 2006; Swart et al., 2003). Given the extent of damage caused by sinkholes due to mining and human activities, the current study focuses on the causes and impacts of sinkholes, and also on possible strategies that can be adopted by the residents of MLM and the City Council in order to reduce the risks associated with sinkholes. The sinkhole risk reduction strategy also proposes a system that will eliminate or mitigate the occurrence of sinkholes by proactively monitoring and responding to aspects that lead to the formation of sinkholes. | en_US |
