An Improved Persistent Scatterer Interferometry for Subsidence Monitoring in the Tehran Basin

The Southwestern Tehran basin is covered primarily by agricultural fields and is subjected to significant levels of land subsidence phenomena. Conventional SAR interferometry cannot extract deformation information from the available SAR images due to large spatial baselines and temporal de-correlation. Moreover, the proper Persistent Scatterer interferometry method for a rural area (StaMPS, Stanford method for Persistent Scatterer) cannot efficiently operate in areas with high deformation, such as the Tehran basin, because of unwrapping error caused by temporal aliasing of the signal. Therefore, in this work, a method based on StaMPS is developed to address the unwrapping error in the Tehran basin. In the proposed method, the estimated deformation rate from the wrapped phase and the periodogram approach are used to reduce the likelihood of aliasing, and StaMPS is subsequently applied to the residual phase. The method is applied to ENVISAT ASAR images captured between 2003 and 2008, and the mean precision of the estimated deformation is approximately 2.5 mm/yr. A comparison of the results obtained from the proposed method with those from continuous GPS and leveling measurements demonstrates its efficiency.