Abstract
Abstract. Ground subsidence is one of the key factors causing damages to transportation facilities, e.g., transportation network (TN) consists of highways and railways. For better exploration of TN subsidence, we propose to use the high resolution TerraSAR-X (TSX) persistent scatterer interferometry (PSI) approach to extract regional scale (RS) subsidence related to the TN. The primary procedures involve interferometric pair selection, interferogram generation, persistent scatterer (PS) detection, PS networking, phase parameterization and subsidence estimation. Xiqing district of southwest Tianjin (China) is selected as the study area, in which multiple highways and one railway line are located. 15 TSX images collected over this area between March, 2009 and June, 2010 are utilized to extract subsidence by the TSX PSI approach. The subsidence rate (SR) map shows that remarkably uneven subsidence occurs along and around the TN, and the SR ranges between –69 and –1.3 mm/yr. For validation purpose, the SR of the TN derived by PSI is compared with leveling data collected for the benchmarks deployed along the selected highways. The mean and root mean square error (RMSE) of discrepancies between two data sets are 0.1 and ±3.2 mm/yr, respectively. The numerical analysis indicates that the high resolution TSX PSI is able to reveal comprehensive and detailed subsidence related to the TN with a millimeter level accuracy.
Highlights
It is well known that transportation plays a significant role in the development of national economy and the daily life of citizens [1, 2]
The results indicate that our study area is a predicably active zone for subsidence
For better exploration of subsidence related to the transportation network (TN), we propose to use high resolution TSX persistent scatterer interferometry (PSI) approach to monitor the regional scale subsidence both along and around the TN
Summary
It is well known that transportation plays a significant role in the development of national economy and the daily life of citizens [1, 2]. InSAR technique is inevitably affected by spatiotemporal decorrelation [7] and atmospheric delay [8], which significantly reduce the accuracy of InSAR measurements To overcome such drawbacks, Ferretti et al proposed the persistent scatterer interferometry (PSI) method in 2001 [9]. The recent X-band radar sensor onboard the German satellite TerraSAR-X (TSX) has capability of providing SAR images at very high spatial and temporal resolution of about 1–3 m and 11 days, respectively [13]. This extends the data availability for subsidence detection by PSI [13, 14]. To assess the accuracy of TN subsidence derived by the presented PSI approach, the subsidence of the TN measured by leveling are used as the reference data for comparative analysis
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