Spatio-temporal change analysis of glacial lakes in Himachal Himalayas using geospatial technology

Extreme weather events, such as cloud bursts, temperature inversions, and landslides, along with the effects of global warming, act as catalysts for snowmelt and contribute to the expansion of existing glacial lakes in mountainous regions like the Himalayas of Himachal Pradesh, India. The additional water load in these glacial lakes, caused by snowmelt and extreme rainfall events, can lead to glacial lake outburst floods (GLOFs), a phenomenon that is both difficult to map and inaccessible. These GLOF events pose significant hazards to the region and its inhabitants. Therefore, it is crucial to map and monitor glacial lakes using remote sensing and geographic information system (GIS) techniques. The present research focuses on the spatio-temporal mapping of glacial lakes in a part of Himachal Pradesh, India, utilizing Landsat satellite time series data from 1980 to 2017. The years 1980, 1990, 2000, 2010, and 2017 were selected for mapping using the well-known normalized difference water index (NDWI > 0.25) in the earth resource data analysis system (ERDAS) modeler. Results indicated a continuous increase in both the number and extent of glacial lakes during the study period. In 1980, there were 102 glacial lakes covering an area of 222.8 hectares. By 2017, the number of glacial lakes had increased to 783, covering an area of 955.6 hectares. It was observed that while some lakes appeared and others disappeared during the study period, the appearance of lakes was more prominent in higher elevation ranges (4000-5500 meters), making this a potentially vulnerable altitude zone for GLOF hazards. The study provides a foundation for further monitoring of lake dynamics and identifying possible GLOF-prone areas, offering valuable information for policymakers involved in the management of hilly habitats and for researchers globally.