Understanding Glacial Lake Evolution and the Associated GLOF Hazard in the Shyok Catchment of the Upper Indus Basin Using Geospatial Techniques

As glaciers recede in response to global climate change, significant growth of glacial lakes is being witnessed in the Himalayan region. Owing to their high elevations, rapid growth, and their occurrence behind loosely consolidated glacial moraine deposits, these lakes pose a significant threat of glacial lake outburst floods (GLOFs). This study focused on tracing the glacial lake evolution in the Shyok catchment of the Upper Indus Basin over a 30-year period (1992–2022) and carrying out a GLOF hazard assessment. Multitemporal medium- and high-resolution satellite imagery was used to inventorize, detect spatiotemporal change in, and classify glacial lakes with areas more than $0.001{\mathrm{km}}^2$, as well as to extract various lake characteristics. The GLOF hazard assessment was carried out using a multicriteria approach based on the analytical hierarchy process (AHP). We found significant increases in the total number, from 143 (1992) to 240 (2022), and combined area, from $8.45\pm 0.02{\mathrm{km}}^2$ (1992) to $13.26\pm 0.04{\mathrm{km}}^2$ (2022), of glacial lakes. Out of 63 glacial lakes with areas $>0.05{\mathrm{km}}^2$, four lakes were classified as very-high-hazard lakes, with GLOF susceptibility indices above 0.75, and 12 were classified as high-hazard lakes, with GLOF susceptibilities indices of 0.66–0.75. These hazardous lakes have had a high growth rate owing to increasing temperature trends in the region. Our findings also suggest that the GLOF hazard of these lakes is going to continue increasing as a result of lake expansion and enhanced exposure to landslides and avalanches. The identification of potentially dangerous glacial lakes and assessing their GLOF hazard will help prioritize future research and develop better mitigation strategies for potential future disasters in the area.