Surface Deformation Modelling Using C-Band SAR Data—A Case Study on Shimla Town, Himachal Pradesh, India

SAR datasets play an active role in monitoring the active deformation not only due to its high radiometric resolution, but also increased temporal resolution (12 days) and greater swath coverage. The European Space Agency (ESA) provides SAR dataset through its twin constellation of satellites Sentinel 1A and 1B which has a huge impact in data analysis not only for deformation studies, but also in other thrust areas and earth related studies. The study area chosen for the deformation modelling is Shimla Municipal Corporation. According to Seismic Vulnerable zone classification by India, Shimla is present in Zone IV with high vulnerability. The region is also highly prone to disasters such as earthquake, landslides, flash floods, improper building construction due to natural and anthropogenic causes. The deformation rate has been calculated between 2014 and 2015. The datasets were acquired from Sentinel Data Hub organized by ESA. Four C—Band Sentinel—1A SLC TOPSAR data at ascending orbit with dual polarization has been used for deformation analysis. Precise orbit files were applied to the data and then each successive data was coregistered as Master and Slave Image. Three interferograms were formed and used for the analysis. These images were then subject to further pre-processing such as topographic phase removal and phase filtering to smoothen the interferograms. The unwrapped image was acquired by analysing the image through SNAPHU in Linux environment. The output received was converted into displacement data through band math into mm units. The results indicate that the surface has subsided nearly−33 to−100 mm/year between 2014 to 2015 and 2016 to 2017. The surface has an upliftment of 39 to 45 mm/year between 2015 and 2016. The result obtained in this study from measuring active monitoring of ground deformation and rate will help stake holders and government authorities to take necessary steps in constructing built-up lands and other environmental related projects.