Land Subsidence Investigation Along Railway Using Permanent Scatterers SAR Interferometry

Land subsidence is a common geohazards in many countries of the world, which cause damages for many urban areas and civil infrastructure. The development of spaceborne SAR interferometry provides an efficient tool for large spatial scale surface deformation monitoring with a high accuracy and precision. This paper presents a case study of land subsidence investigation along railway by using Permanent Scatterers SAR interferometry (PSI). Based upon the conventional InSAR techniques, PS-InSAR overcomes atmospheric delay anomalies and temporal and geometric decorrelation by exploiting the temporal and spatial characteristics of radar interferometric signatures collected from point-wise targets that preserve phase coherent over time. In this work, a linear model is adopted to retrieval land subsidence rate by using the differential phase series of the permanent scatterers. For the subsidence rate derivation along the railway, a buffer with a width of 10 km is set up and those PS within the buffer is interpolated to generate the subsidence map. The results archived using ENVISAT ASAR images acquired from 2003 to 2004 are validated with the precise leveling data and used to investigate the Jing-Jin railway in north china.