Assessment of high-position glacial valleys in Southeast Tibet, China: an integrated approach using remote sensing, UAV, field investigation, and numerical simulation

The destabilization of glacial valley deposits in high position poses a substantial risk to both the valleys themselves and the infrastructure located downstream. However, the inherently challenging accessibility of these high-altitude regions complicates the task of conducting thorough stability assessments. This study introduces a comprehensive identification methodology that integrates remote sensing technology with air-ground surveys to investigate the stability of high-position glacial valleys, thereby laying the groundwork for subsequent stability evaluations in areas prone to deformation. To exemplify the effectiveness of this approach, three glacial valleys situated at an average altitude exceeding 4500 m in Basu County, Southeast Tibet, China, were selected for case study analysis. The findings reveal that significant landslide events within these high-position glacial valleys can be discerned by comparing reference points in optical satellite imagery. In the 2# glacial valley, substantial deformation is concentrated along the central axis, whereas in the 1# and 3# glacial valleys, deformation is predominantly observed in the scarp regions, as determined by Interferometric Synthetic Aperture Radar (InSAR) analysis. The principal sliding zone is identified within the altitudinal transition zone between 4400 and 4700 m. The maximum deformations recorded under a 24-h, 200-year return period rainfall event and a 15-s seismic event with an acceleration of 0.41 g (g = 9.8 m/s2) were 1.66 m and 6.7 m, respectively. This integrated approach provides a practical framework for the investigation of high-position glacial valleys, thereby facilitating the assessment and mitigation of geological hazards in these otherwise inaccessible environments.