Process Chain of a Potential Transboundary Glacial Lake Outburst Flood at Qiangzongke Co, Southwestern Tibet, China, Using Multi-Source Data and Hydrodynamic Modeling

Abstract The acceleration of climate change has led to an increase in the frequency of glacial lake outburst floods (GLOFs) in the Himalayas, resulting in significant devastation. InSAR data indicate that Qiangzongke Co, located in southwestern Tibet, China near the China-Nepal border, experienced considerable deformation of the adjacent terrain over recent decades, implying a potential landslide. Landslide entry into a glacial lake typically initiates surge waves that propagate forward, eroding the moraine dam and ultimately inducing a GLOF disaster. This study integrated multi-source data and hydrodynamic models to assess the potential GLOF process chain and downstream impact. The results indicate that the surface area of Qiangzongke Co has increased by 194% from 1975 to 2024. From 2018 to 2024, an unstable slope area was identified on the lakefront bank in the upper reaches of northern Qiangzongke Co, with a maximum annual displacement rate of over 100 mm. The potential landslide-induced GLOF is estimated to reach a peak discharge of 1.9 × 10 4 m 3 /s, threatening 101 buildings in China and 45 in Nepal. This research can effectively facilitate the establishment of GLOF early warning systems, the planning of major projects, and the development of regional disaster prevention frameworks.