Bolvadin Subsidence Analysis with Multi-Temporal InSAR Technique and Sentinel-1 Data

Surface deformations in Bolvadin town without any devastating earthquakes have been observed in the last 10 years. In this study, ground deformation analysis of Bolvadin region was performed by Sentinel-1 synthetic aperture radar (SAR) data and multi-temporal SAR interferometry (InSAR) method. Sentinel-1 images obtained between October 2014 and October 2018 in ascending and descending orbits were processed with SNAP and StaMPS softwares. Deformation velocity maps and vertical displacement time series were produced and compared with geology and groundwater level of the region. Deformation velocity maps show significant subsidence in the region. The most severe subsidence, up to 35 mm/year, was found in the southern part of Bolvadin which is characterized by the presence of soft alluvial deposits. Both in long and short term, there was a strong correlation between the subsidence and the groundwater level. As a result, the high correlation of the vertical deformation velocity with lithological units and groundwater level indicates that subsidence in the region is probably due to the excessive use of groundwater.