Sinkhole and subsidence size distribution across dolomitic land in Gauteng

Abstract

Karst-related sinkholes and subsidences occur on areas underlain by Chuniespoort Group dolomite bedrock in the Gauteng Province, South Africa. Although dolomite land is found across several South African provinces, sinkhole and subsidence formation in Gauteng, the economic hub of South Africa, has been considerably more severe than in other provinces. Thousands of sinkhole and subsidence events have occurred in the past 50 years. Previously, data on sinkhole and subsidence occurrence was amassed separately by various consultants, companies, research institutions and state authorities. There is no legal requirement for sinkhole and subsidence events to be reported to a central authority, yet the data is crucial for future assessment of sinkhole hazards and decision-making. Information regarding the sinkhole record for Gauteng was collated to develop an inventory of the study area. Compiling a comprehensive database presented many challenges; most importantly the large volume of incomplete data that could not be retrieved. Sinkholes, and subsidence and crack events prior to the end of 2011 were considered for Gauteng. Data was organised into multi-wave frequency tables, and various aspects were then analysed. This paper deals with available dimension data (i.e. diameter and depth) across the Gauteng Province.