Inventory and recently increasing GLOF susceptibility of glacial lakes in Sikkim, Eastern Himalaya

Climatic changes alter the climate system, leading to a decrease of glacier mass volumes and swelling glacial lakes. This study provides a new inventory of glacial and high-altitude lakes for Sikkim, Eastern Himalaya, and evaluates the susceptibility of lakes to Glacial Lake Outburst Flood (GLOF). By using satellite data of high spatial resolution (5 m), we obtain 1104 glacial and high-altitude lakes with total area 30.498 km2, of which 472 have an area > 0.01 km2. Applying pre-defined GLOF susceptibility criteria on these 472 lakes yields 21 lakes susceptible to GLOF, which all increased in area from 1972-2015. Using Analytic Hierarchy Processes (AHP), the pairwise comparison matrix further reveals that 5 of these glacial lakes have low, 14 have medium and 2 have high GLOF susceptibility. Especially these 16 glacial lakes with high and medium GLOF susceptibility may threaten downstream communities and infrastructure and need further attention.