Multiple phases of ice-dammed lake formation and drainage associated with a surge of Shisper Glacier, western Karakoram

Glacier surges can create ice-dammed lakes when the advancing terminus blocks drainage. Such lakes are inherently unstable and can drain abruptly as glacial lake outburst floods (GLOFs), presenting a hazard to downstream populations and infrastructure in high mountain environments. We present satellite image analysis of the evolution of an ice-dammed lake formed by the 2018-20 surge of Shisper Glacier, western Karakoram. Our analysis identifies six phases of lake evolution. A large lake of up to 33.7 ± 9% million m3 formed in 2018-19, 2019-20, 2020-21 and 2021-22. In each case, the lake began to fill late in the year, reached a maximum size in May, and had completely drained between May and July, typically over 1-2 days. This analysis provides further evidence that GLOF hazards associated with lakes dammed by glacier surges can persist for several years after surge termination.