Genesis and spatio-temporal analysis of glacial lakes in the peri-glacial environment of Western Himalayas

Abstract

Glaciers are retreating in the highest mountainous regions of the world, like Himalayan region as a result of climate change and global warming. This leads to the formation of different types of glacial lakes. These lakes are not only the source of fresh water but it also causes disaster in the form of Glacial Lake Outburst Flood (GLOF). Astore Drainage Basin is located in north eastern mountainous region of Himalayas. This area is prone to GLOFs because of the increasing number of glacial lakes and the growth of existing lakes as a result of global warming. To provide a detailed information about the spatial and temporal information of glacial lakes detailed inventories has been developed for the study area using Landsat images for the year 1989, 1999, 2009 and 2019. Glacial lakes were mapped and identified by using Normalized Different Water Index, Normalized Difference Snow Index and high-resolution Google Earth images. It was found from the analysis that the number of the glacial lakes increased from 120 to 128 in a period of thirty years (i.e., from 1989 to 2019). During the study period two lakes disappeared whereas ten new lakes were formed. There were 21 lakes which show area expansion more than 100% representing high susceptibility for GLOF. The results also showed that smaller lakes expanded more rapidly in area than the larger lakes.