Abstract

Abstract. This paper presents an improved approach of multi-temporal interferometric synthetic aperture radar (InSAR) for detecting land subsidence phenomena by using time series of high resolution SAR images. Our algorithm extends the capability of the temporarily coherent point (TCP) InSAR technique proposed previously to detect subsidence even in the case of a small number of SAR images available for a study area. The approach proposed in this paper is implemented by using the interferograms with ultrashort spatial baselines (USB) through several procedures, including selection of USB interferometric pairs, TCP identification, TCP networking and modeling, as well as TCP solution. As the topographic effects are negligible in the USB interferograms, an external digital elevation model is no longer necessary for differential processing, thus simplifying both TCP modeling and parameter estimating. The algorithm has been tested with the high resolution TerraSAR-X (TSX) images acquired over Tianjin (China), and validated by using the ground-based leveling measurements. The testing results indicate that the density and coverage extent of TCPs can be increased dramatically, and the quality of subsidence measurements derived by the USB-based TCPInSAR can be raised.

Highlights

  • Land subsidence is a common hazard that is usually caused by anthropic activities, which can bring severe consequences

  • It is evident that the accuracies in subsidence rates derived by the ultrashort spatial baselines (USB)-based temporarily coherent point (TCP) solution are almost two times higher than those derived by the long spatial baselines (LSB)-based TCP solution

  • It is demonstrated that the accuracies in the subsidence measurements derived by the USB-based TCP solution are about two times higher than those derived by the LSB-based TCP solution

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Summary

Introduction

Land subsidence is a common hazard that is usually caused by anthropic activities, which can bring severe consequences. The subsidence measurements derived by InSAR are often degraded by two factors, i.e., spatial and temporal decorrelation (Massonnet & Feigl, 1998; Rosen et al, 2000; Liu, 2006; Zebker & Villaseno, 1992) and atmospheric artifacts, (e.g., Zebker & Villaseno, 1992; Buckley, 2000; Liu, 2003; Ding et al, 2004). The persistent scatterer InSAR (PSI) technique is one of the advanced approaches of multi-temporal InSAR, which have been proposed in recent years to mitigate the technical limitations of InSAR, (Ferretti et al, 2000; Ferretti et al, 2001). The temporarily coherent point InSAR (TCPInSAR) is an alternative implementation of PSI, which was proposed by Zhang et al (2011a, 2011b). As the selection of TCPs can be performed on a minimum of two SAR images, TCPInSAR is more advantageous when there are few SAR images available over an area of interest for deformation detection (Zhang et al, 2011b)

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