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Seasonal deformation features on Qinghai-Tibet railway observed using time-series InSAR technique with high-resolution TerraSAR-X images

Wang, Chao, Zhang, Zhengjia, Zhang, Hong, Wu, Qingbai, Zhang, Bo, Tang, Yixian
Remote sensing letters 2017 v.8 no.1 pp. 1-10
climate change, cooling, deformation, equations, freezing, humans, interferometry, models, monitoring, permafrost, railroads, remote sensing, thawing, time series analysis, variance, China
Climate change and human activity are changing the dynamics of the Qinghai-Tibet Plateau (QTP) environmental balance, which impacts the safety and stability of its infrastructure. The Qinghai-Tibet Railway (QTR) is the longest structure in the QTP, and some sections of the QTR’s embankment have been damaged due to freezing and thawing of permafrost. In this article, a modified SAR interferometry (InSAR) method for deformation monitoring is proposed and implemented. In this method, a seasonal deformation model based on the simplified Stefan equation has been adopted to measure the seasonal displacement. In particular, a linked coherence model is used to improve the effect of temporal correlation by defining a coherence parameter in the neighbouring pixel network. It was found that most of the study area had seasonal displacements of up to 20 mm. The deformation cross-section profile of the railway shows asymmetry between the two sides of the railway subgrade shoulders which may be related to sunny-shady slope effect. It was found that variable deformation along the QTR ranges from 0 to 30 mm, probably due to underlying permafrost conditions. Displacements of the experimental railway subgrade segment with varying types of cooling measurements are different, which shows their cooling efficiency variance.