Subsidence Monitoring in Railway Lines with LICSBAS Algorithm and Radar Interferometric Method (Case Study: Mashhad-Sarkhs Railway)

Articles in Press

Document Type : Research Article

Authors

• Soroush Yasini ¹
• Hossein Etemadfard ²

¹ Department of Environment, Faculty of Natural Resources and Environment, Ferdowsi University of Mashhad, Mashhad, Iran

² Civil Engineering Department, Engineering Faculty, Ferdowsi University of Mashhad (FUM)

10.22067/geoeh.2024.87783.1480

Abstract

In recent times, the increasing occurrence of subsidence has raised concerns, particularly in Iran's plains, urban regions, and transportation infrastructures. This study focuses on understanding how this phenomenon affects the Mashhad-Sarkhs railway since it is located on the eastern end of Iran's rail network and serves as a vital link railroad connecting to the nation's Central Asia nations which are important trade partners. There are critical concerns because the route crosses through three restricted groundwater extraction plains due to their extremely low groundwater levels. To assess the subsidence rate along it, 151 radar images were processed that are between 2017 and 2023 utilizing the new NSBAS algorithm and pre-processed data from COMET LiCSAR to calculate the cumulative subsidence rate. To reduce atmospheric effects on subsidence rate estimation the GACOS portal minimizes errors caused by the atmospheric condition variation. The loop closure algorithm is used for interferometric network refinement and detects unsuitable interferograms containing various errors, including unwrapping errors. Following this, we made a land cover map of the study area with four land use classes using the Google Earth Engine to investigate the effects of land cover variations on subsidence. Finally, a subsidence profile was prepared around the railroad and combined the profile with land use classes. The results show three land subsidence zones along the rail, with some areas experiencing subsidence exceeding 200 mm. The results indicate a strong correlation between rail subsidence and farming within the rail zone. Conversely, there were almost no signs of land subsidence outside of the plains, due to the absence of concentrated agricultural activities. The first 60 kilometers of the railroad, which has more than 20 bridges, was identified as the most concerning subsidence zone along the rail track.

Keywords

• Subsidence
• hazards
• land use
• structure settlement
• transportation

Main Subjects

• Land subsidence

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