A Multi-year Analysis of Supraglacial Lake Seasonal Dynamics in the Karakoram

Imran Khan , Mahsa Moradi, Jennifer M. Jacobs, Joseph Licciardi

Supraglacial lakes are a key feature of many debris-covered glaciers in the Karakoram region. These lakes are highly dynamic, often forming and draining rapidly on seasonal timescales. However, due to their small size and transient nature, they are largely absent from regional and global glacial lake inventories. In this study, we used Sentinel-1 synthetic aperture radar (SAR) imagery to examine the seasonal (May to September) and interannual (2017 to 2023) dynamics of supraglacial lakes across six glaciers in the Karakoram at scales from 0.001 to 0.50 km2. Our results show that small (<0.01 km2) and ephemeral lakes dominate in number, with lake occurrence decreasing sharply as size increases. The lakes had a consistent seasonal pattern, with lake numbers and cumulative area peaking early in the melt season (May or June). Lake formation was concentrated on nearly stagnant glacier surfaces characterized by a debris thickness of less than 0.5 m and a surface slope of less than 9 degrees. This study provides new insights into supraglacial lake dynamics across the Karakoram by quantifying their prevalence, seasonality, and surface controls. These findings are important for evaluating potential downstream hydrologic and hazard impacts and improving our understanding of glacier hydrology and melt processes.