Surface Deformation Monitoring along Qinghai-tibet Railway Using Small Baseline Sar Interferometry, a Case Study of Beiluhe Section, Qinghai, China

The project of Qinghai-Tibet Railway (QTR) confronts the challenge of surface displacements resulted from seasonal freezing bulge, thawing subsidence and compression settlement. Therefore the embankment instability monitoring is essential for policy makers as well as emergency managers for its operational safety. In this study, we implemented SAR interferometry for extracting ground deformations along the railway. In total, 38 Envisat ASAR SLC images, spanning from 18 Nov. 2004 to 17 Dec. 2009, were employed to cover the Beiluhe experimental site, Qinghai, China. Based on the small baseline interferometric combination (smaller than 300 m spatially and 175 days temporally), 49 high coherent interferograms were firstly generated to minimize the seasonal decorrelation. Then, the estimated surface deformation rates were compared between stacking and Persistent Scatterers Interferometry (PSI); the result revealed a good agreement with determination coefficient of 0.863 for a linear regression model. Furthermore, the derived deformation rates along the embankment were distinct (-20 to +20 mm/yr) in 5 years, implying the necessity of continued satellite-based surveillance along the QTR.