A thermal-hydro-mechanical coupled analysis model for climate-driven movements of valley glaciers (THM-GA 1.0)

A singular phenomenon was observed worldwide: multiple valley glaciers (volume > 10⁶ m³) on gentle slopes (∼10°), previously considered stable, are now accelerating or even destabilizing. The mechanisms behind this issue remain not fully understood, and prediction models are lacking due to the complex nature of the multi-physical processes involved. This study develops a coupled thermo-hydro-mechanical glacier analysis model (THM-GA 1.0) to analyze climate-driven glacier motions. The unique features of the proposed model are hydro-mechanical feedback and glacier dynamics coupled with the thermomechanical behavior of debris-ice mixtures. The model is verified by three benchmark tests and applied to analyze the Sedongpu glacier (29.80°N, 94.92°E) in Yarlung Tsangpo Grand Canyon, Southeast Tibet, serving as a real-world validation case. Results show that the warming climate enhances the intricate interplay between seasonal variations and glacier dynamics. The polythermal structure within glaciers fosters long-term non-uniform movements, facilitating crevasse propagation and water infiltration. The infiltrated water in the soft and deformable glacial bed elevates basal pore-water pressure, reduces basal sliding resistance, and accelerates glacier movements or destabilization. Our findings reveal that the unprecedented increased low-angle glacier movements are attributed to the mutual feedback between temperature-induced crevasse propagation and basal hydrology. This study contributes to understanding climate-driven glacier movements and mitigating glacier hazards.