Improved Ground Subsidence Monitoring Using Small Baseline SAR Interferograms and a Weighted Least Squares Inversion Algorithm

We present the application of a weighted least squares (WLS) method based on image mode interferometric data to monitor the spatiotemporal evolution of land surface subsidence in Mashhad valley, northeast Iran. The technique is based on an appropriate combination of differential interferograms produ...

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Bibliographic Details
Published in:IEEE geoscience and remote sensing letters 2012-05, Vol.9 (3), p.437-441
Main Authors: Akbari, V., Motagh, M.
Format: Article
Language:English
Subjects:
Algorithms
Coherence
Covariance matrix
Envisat satellite
Extraterrestrial measurements
Global Positioning System
Global Positioning System (GPS)
Interferometry
Least squares method
Northeast
Orbitals
Studies
Subsidence
Synthetic aperture radar
synthetic aperture radar (SAR)
time series
Valleys
weighted least squares (WLS) adjustment
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Summary:We present the application of a weighted least squares (WLS) method based on image mode interferometric data to monitor the spatiotemporal evolution of land surface subsidence in Mashhad valley, northeast Iran. The technique is based on an appropriate combination of differential interferograms produced by image pairs with small orbital separation to limit the spatial decorrelation phenomena. Our data consist of 17 ASAR single-look-complex images acquired from a descending orbit by the European ENVISAT satellite in image mode (I2), spanning a time interval from June 2004 to November 2007. Fifty-three reliable differential interferograms with relatively little noise and a continuous unwrapped phase are constructed from this data set and are analyzed using a WLS adjustment technique to produce time series of the displacement field. The time-series analysis suggests that the subsidence occurs within a northwest-southeast elongated elliptically shaped bowl along the axis of Mashhad valley. The maximum accumulated subsidence during the 1260-day period reaches approximately 86 cm, located northeast of Mashhad city. The comparison between SAR-interferometry time-series results with continuous Global Positioning System measurements yields an estimated root-mean-square error of ~ 1.0 cm.
ISSN:1545-598X
1558-0571
DOI:10.1109/LGRS.2011.2170952