Determining Susceptibility to Sinkholes Due To Climatic Factors in Ekurhuleni: A Multi-Criteria Decision-Making Approach

The occurrence frequency and intensity of many geoenvironmental hazards such as landslides and sinkholes have increased over the years, partly due to climate change. However, the effects of such occurrences and the spread of sinkholes have not been thoroughly explored by researchers in South Africa. Most research shows that water ingress caused by water pipe leakages and water table movements are the common causes that exacerbate the increase of sinkhole occurrences. The Ekurhuleni Municipality is known to have 52% dolomite coverage, affecting most low-income areas in the city. This environmental constraint has caused huge amounts of developable land loss as well as financial loss in the city. Consequently, this study aims to assess the likelihood of sinkholes occurring and their spatial susceptibility, by using the Analytic Hierarchy Process (AHP) as a multi-criteria decision-making method. Nine sinkhole factors were prepared, including dolomite, shallow undermining, proximity to mines, average annual rainfall, hydrology, MSDF (urban development), elevation, soil type, and groundwater yield. Susceptibility maps were then prepared using the GIS-MCDA methodology. The results show that 12% of the city is highly susceptible to sinkhole occurrences, with 20% moderately susceptible, 26% marginally susceptible and 42% not likely to be affected. The highly susceptible areas are mostly located in the southern and northern parts of the city.