Monitoring Glacial Lakes in High Mountain Asia from 2008 to 2016

Glacial lake outburst floods (GLOFs) are among the most serious natural hazards in mountainous regions in the last several decades. The recent global warming has caused dramatic glacial lake changes and increased potential GLOF risk, particularly in High Mountain Asia (HMA) region. Thus, there is a pressing need to detect and monitor lake area changes and spatial distribution of glacial lakes in this region. In this research, we produce more accurate and complete maps of glacial lake extent in the HMA in 2008, 2012 and 2016 with consistent time intervals using Landsat satellite images and the Google Earth Engine (GEE) cloud computing platform, and further study the formation, distribution and dynamics of the glacial lakes. In total 17016 and 21249 glacial lakes were detected in 2008 and 2016, respectively, covering an area of 1420.15±232.76 km² and 1577.38±288.82 km²; the lakes were mainly located at altitudes between 4400 m and 5600 m. The annual areal expansion rate was approximately 1.38 % from 2008 to 2016. To explore the cause of the rapid expansion of individual glacial lake, we investigate their long-term expansion rates by measuring changes in shoreline positions. The results show that glacial lakes are expanding rapidly in areas close to glaciers, had a high expansion rate of larger than 20 m/yr from 2008 to 2016. Glacial lakes in the Himalayas show the highest expansion rate of more than 2m/yr, followed by the Karakoram Mountains (1.61 m/yr) and the Tianshan Mountains (1.52 m/yr). The accelerating rate of glacier ice and snow melting caused by global warming is the primary contributor to glacial lake growth. These results may provide information that will help in the understanding of lake detailed dynamics and the mechanism, and also facilitate the scientific recognition of the potential hazards associated with glacial lakes.