From Surge to Flood: GLOF Hazards Linked to Glacier Surges in the Upper Shyok Valley

Glaciers in the Karakoram range are known to surge periodically, often triggering glacial lake outburst floods (GLOFs). However, the Shyok Valley remains comparatively understudied in this context. This study examines the surge dynamics of five glaciers- Aktash, Kichik Kumden, Chong Kumden, South Rimo-X, and Central Rimo, in the upper Shyok Valley of the Eastern Karakoram range, mapping their movements and the formation of associated lakes caused by ice-dammed river blockages. Between 1996 and 2025, three distinct lake sites formed. Two of these lakes filled and drained multiple times, while the third filled and drained only once. In total, six major outburst events and several minor drainage events were identified, including multiple previously undocumented events. While glacier surging is generally understood to follow cyclical behaviour, no consistent recurrence interval was observed in this study. Notably, GLOF locations were found to repeat, driven by the same glaciers periodically surging and obstructing the same river channels. The estimated lake volumes are comparable to those of known GLOF-producing lakes in the western Karakoram. These glaciers pose notable flood hazards due to their potential for large-scale ice dam formation and subsequent outbursts. Overall, this study contributes to further understanding of glacier surge dynamics in the eastern Karakoram, the GLOF hazards they pose and the likelihood of these events repeating.