Interferometric Processing Time Series COSMO-SkyMed Pictures to Calculate Subsidence Rate of the Ground and Underground Structures

The study of surface displacement, particularly subsidence occurred in important ground and underground structures, and identification of surface dynamic behavior of these structures are always one of the major challenges in recent centuries that have too much costs for various organization. So far, there are several tools to measure the surface displacement, among them; one can point to Global Positioning System (GPS) and precision leveling. These tools measures the surface displacement of the earth at large scales (spatial and temporal) with high precision. However, despite the advantages of this method, these tools often very costly, time consuming and requires intensive field work, and additional this method carried out over a small area and only on a limited number of target points or on a single line which passes through the area. Therefore, do not extract the full details of the deformation field in space and time. These reasons have caused attention to a method that reduces these limitations. In the resent year one of the newly technique for detected this displacement and subsidence is the Interferometry Synthetic Aperture Radar (InSAR), persistent/permanent scatterer interferometry (PSInSAR) was developed to improve the accuracy and precision of the deformation measurements, even reach to sub-millimeter level. They are several algorithms for deformation monitoring using PSInSAR, this methods uses a huge collection of stable pixels (PSs) for processing which are known as coherent targets how stable the phase over the time. Use of PSs points causes further increasing the spatial density of deformation-tracking points or improve the accuracy of deformation measurements, therefore in this study used of the persistent/permanent scatterer Interferometry Synthetic Aperture Radar (PSInSAR) and height resolution radar image in order to investigation the subsidence of structures and important ground and underground targets in Tehran city between 2014 to 2016. Our radar data set consists of 13 StripMap HIMAGE, right-looking, ascending mode scenes with an image swath of 40 km, which were acquired at 3-m resolution and with HH polarization, between 2014 to 2016, from the SAR sensors on-board the four satellites of the COSMO-SkyMed constellation, at a ~620-km altitude above the Earth’s surface with an LOS incidence angle of 36° at the scene centre, a minimum of 32.4° and a maximum of 35.5° at the near and far range, respectively, In present study, StaMPS persistent scatterer approach, under SBAS and PS algorithms is used for investigation of time series Interferometric analysis. The results of both processing indicated that significant subsidence in southwest part of Tehran city and in 9, 17, 18, 19 and 21 districts of Tehran municipality during this two year, is occurred which average rate of it is around of 61 mm/year. Furthermore, in this study, displacements occurred in the location of some important structures including Milad tower, Azadi stadium, Azadi tower and Mehrabad airport and also surface displacement enroute Tehran subway, based on extracted results from time series radar Interferometric processing and detecting of danger regions, is evaluated. As a result of this evaluation, the regions that are subject of danger (regions exposed to danger), would be identified and introduced to related organizations for suitable prevention function in future.