Seasonal subsidence retrieval with Coherent Point Target SAR Interferometry: A case study in Dezhou city

Spaceborne Radar Interferometry (InSAR) is well known as an accurate, time saving and low cost technique for monitoring of surface deformation phenomena ranging from land subsidence, volcano displacement, tectonic motion and even slow landslides. The Coherent Point Target SAR Interferometry (CPT-InSAR) overcomes atmospheric delay anomalies and the temporal and geometric decorrelation by the interferometric calculating of point-wise targets which maintain high coherent. The linear and no-linear subsidence can be retrieved by CPT-InSAR, which can be done well even with less than 20 SAR images by integrating the SBAS (Small Baseline Subset) and PSI (Permanent Scatterers InSAR) techniques. The application of the proposed method to monitor seasonal land subsidence in the Dezhou city, a medium city in Shandong province in North China Plain (NCP), is described. The presented results, obtained by processing of ENVISAT ASAR data acquired between Mar, 2004 and Dec, 2008, are highly agreed with the deep groundwater level, including the spatial position and variation tendency.