Managing the sinkhole hazard.

The densely populated Gauteng Province of South Africa includes the cities of Johannesburg and Pretoria but 25% of it sits on dolomite rock making it highly susceptible to sinkholes. Local changes in ground or building movement can provide early warning of sinkholes, but regularly surveying the 5,000km² of dolomite in Gauteng would be too expensive and impractical.

In a polit study of this area for Gautrain and the University of Pretoria, precursors to known sinkhole events were identified by InSAR analysis of the entire Gauteng area, suggesting that the majority of sinkhole occurrences could be foreseen by these techniques.

InSAR analysis proved a cost-effective method to provide an early warning of more sinkhole events. Proactive maintenance facilitated by such insights reduces the danger, cost, and disruption of sinkhole events.

Highlights

• Predicting sinkhole events across large areas is impractical with conventional surveying techniques.

• Precursors to known sinkhole events in the Gauteng province were identified by InSAR analysis.

• The majority of sinkhole events in the Gauteng province could be foreseen by ongoing InSAR monitoring.

InSAR can also be used to assess susceptibility to other geohazards. Read this case study to see how we applied the same methodology to landslide risk.