A comprehensive approach to predicting low-angle glacier detachment-induced river damming: Insights from the Zelunglung Glacier

Glacier detachments in cold, high-altitude regions typically involve large volumes and exhibit extremely high mobility due to the presence of ice, often leading to catastrophic events, and are expected to intensify as global warming continues. Existing studies provide valuable insights into post-event conditions, but predictive efforts based on remote sensing remain limited and often overlook internal glacier structures. This study presents an integrated approach combining remote sensing, geophysical exploration, finite element analysis, and a multiphase flow model to (a) reconstruct glacier geometry, (b) delineate potential detachment zones, and (c) simulate movement and damming hazards. Taking the Zhelunglung Glacier as a case study, we reconstructed the glacier's geometry based on UAV photogrammetry, geophysical measurements, and global glacier thickness datasets. Potential detachment zones were identified by integrating surface features—such as surface bulging, dense flowlines, heterogeneous flow velocities, and supraglacial ponds indicative of compression from tributary glaciers—and internal structural characteristics revealed by geophysical data, which indicate low resistivity and low shear wave velocity zones within the compression area, suggesting internal weak zones. Incorporating these findings, we simulate the potential detachment and subsequent damming process using r.avaflow, a multiphase mass-flow simulation tool, accounting for ice melting and entrainment. The results indicate that a large-scale detachment could affect parts of the village near the gully outlet, with the resulting dammed lake threatening downstream areas. This comprehensive approach enhances the understanding of glacier detachment hazard assessment, emphasizes the role of glacier internal structure, and highlights the value of remote sensing-derived surface data for inferring internal conditions.