Monitoring the Subsidence Induced by Salt Mining in Tuzla, Bosnia and Herzegovina by SBAS-DInSAR Method

Abstract

The ground subsidence induced by salt mining has been causing significant damage in Tuzla, Bosnia and Herzegovina since the 1950s. Several investigations and geodetic surveys have been conducted, i.e., traditional topographic surveys (1950–2003) and static GPS surveys (2004–2007). The last GPS survey (2006–2007) revealed that the subsidence in Tuzla was still occurring at a rate of about − 10 cm/year in some areas. Although monitoring of the subsidence has been on-going at a few points since 2010, by means of the real-time kinematic GNSS method, it lacks spatial coverage. Therefore, an appropriate method is required to monitor the subsidence over an extensive area at a low cost and with less labor time. Differential Interferometry Synthetic Aperture Radar (DInSAR), together with the Small Baseline Subset (SBAS) time-series algorithm, is one of the solutions for use as an effective monitoring tool. The spatial distribution of the subsidence obtained by SBAS-DInSAR shows a good agreement with the subsidence obtained from the former monitoring results. The temporal transition of the subsidence obtained by SBAS-DInSAR is evaluated using the results by the real-time kinematic GNSS monitoring system. It was shown that the DInSAR results coincide with the GNSS results with a discrepancy of less than 10 mm. SBAS-DInSAR detected that the subsidence had almost vanished everywhere, except the north and northeast portions of Pannonica Lake where the rate of subsidence was − 1 to − 4 cm/year during the period of October 2014–May 2019. This study demonstrates that SBAS-DInSAR can be employed as a useful and effective subsidence monitoring tool without the need to install any devices in the monitoring area.