Merging multi-track PSI result for land subsidence mapping over very extended area

The Permanent Scatterer Interferometry (PSI) technique is usually applied for surface deformation mapping at local area from 1 up to a maximum of 100 km². Although the ability to provide deformation map of regional area exceeding 10,000 km², the processed area of interest is mostly limited to SAR acquisitions in a single satellite track and frame. In this work we present the study of merging multi-track PSI results for land subsidence monitoring over very extended area. Apart from the description of the PSI method used for long strip SAR data processing, datum connection of multiple adjacent tracks, including conversion of a common coordinate system and the connection of the PSI derived velocity maps are demonstrated. The application of the proposed method to monitor large coverage land subsidence in the central North China Plain (NCP) is described. The presented results obtained by merging 3 adjacent tracks of ENVISAT ASAR data acquired between Jan, 2007 and Dec, 2009, with a coverage of 200×260km² are very significant and indicate the effectiveness and potential of this technique for land subsidence mapping over very extended area.