Integrating an interferometric synthetic aperture radar technique and numerical simulation to investigate the Tongmai old deposit along the Sichuan-Tibet Railway

Abstract

Numerous old deposits occur in the Eastern Himalayan Syntaxis, especially on the banks of the Yarlung Tsangpo River and its tributaries, where strong tectonic movement and riverine erosion increase the potential for landslides. The possible future deformation and failure processes of these old deposits and their impacts on the surrounding environment are important research topics. Field investigations and temporarily coherent point interferometry synthetic aperture radar (TCP-InSAR) monitoring show that the Tongmai old deposit is prone to catastrophic failure and landsliding. A geomorphological analysis and the related dating results indicate that the Tongmai old deposit consists of residual colluvial or early moraine debris and was formed later than 11.06 ± 0.94 ka BP. The TCP-InSAR analysis indicates that creep deformation is present within the deposit and that this creep is closely related to the precipitation and activity of nearby faults, which may cause slope failure and lead to landslide dam formation. As a result, this study further predicts the likely scale of a landslide dam through numerical simulations. In the worst-case scenario, a landslide will seriously block the Parlung Tsangpo River and form a dam with a height of 100–152 m and a length of approximately 2.4 km. The Tongmai old deposit will likely form a geohazard chain including landslides, barrier lakes, and outburst flooding. Finally, this paper discusses the influence of the Tongmai old deposit on river and landscape evolution.