Large scale land subsidence monitoring with a reduced set of SAR images

In this work we presented the first experimental results of land subsidence mapping for large areas by using Coherent Point Target SAR interferometry with a reduced set of images in the North China Plain (NCP). Since the limitations of the classical Permanent Scatterer InSAR (PSI) for short temporal span surface deformation monitoring due to the dependency on large volumes data availability, we combine the classical PS InSAR and Small Baseline Subset (SBAS) technique in the data processing chain for large coverage InSAR data processing with a reduced set images. The starting point of our study is the generation of small baseline interferograms of the continuous frames in the same track. Following that, each stack of interferograms are processed with CPT InSAR so as to minimize the effect of phase ramp caused by inaccuracy baseline estimation. For large scale land subsidence mapping, all the mean velocity map are merged into a long strip and the subsidence rate of each coherent point are retrieved. The algorithm are tested with 15 ENVISAT ASAR images collected during the period from Jun, 2007 to Nov, 2008 with an extent of 100 × 400 km² in the NCP for land subsidence mapping. The presented results indicates the large scale land subsidence in central NCP and demonstrates the effectiveness the approach.