ESTIMATION OF GROUND DEFORMATION USING PSINSAR WITH L-BAND ALOS PALSAR DATA: A CASE STUDY OF KOLKATA, INDIA

Differential Synthetic Aperture Radar Interferometry (DInSAR) can be used for observing and monitoring land surface change over a large area using multi-temporal SAR images. To remove signal decorrelation issues of DInSAR, Persistent Scatterer InSAR (PSInSAR) has come into practice over the last decade that can measure deformation at small scales and fine accuracy (mm-level). In this paper, we estimate ground deformation of Kolkata, India during 2007-2011 using a spatial correlation based PSInSAR method. Twenty L-band (ALOS PALSAR) SAR images along ascending orbit over Kolkata city were utilised to extract deformation time series, and a validation exercise was carried out using groundwater level data of two wells. PSInSAR extracted a large number of measurement points (363 per km(2) for a total 568014 points), and we found a mean annual deformation rate of -16 to +16 mm/year in Kolkata area along Line-Of-Sight (LOS) of ALOS PALSAR. Comparison between PSInSAR derived deformation and groundwater level fluctuation reveals a good correlation using time series analysis with some discrepancies.