Spatio-temporal Change Analysis of Glacial Lakes in Himalayas of Himachal Pradesh using Geospatial Technology

Abstract Extreme weather events viz. cloud bursting, temperature inversion, landslides etc. along with the other global warming effects acts as the catalyst to snow melt and increase the size of existing glacial lakes in the mountainous regions like Himalayas of Himachal Pradesh. The extra load of water in these glacial lakes as a result of snow melt and extreme events causes ‘Glacial lakes Outburst Flood’ (GLOF) those are very remote phenomena and hard to map and monitored physically. Simultaneously, these events of GLOFs are hazardous for the region and habitants of the hills. Therefore, it is vital to map and monitor such type of glacial lakes with remote sensing and GIS techniques. The present research has been carried out for the spatio-temporal mapping of glacial lakes in the Himachal Pradesh state using Landsat satellite time series data during 1980 to 2017. The year of 1980, 1990, 2000, 2010, and 2017 were selected for the mapping using well known Normalized Difference Water Index (NDWI > 0.25). Results showed a continuous increase in the number and coverage of the glacial lakes during the study period. There were 102 glacial lakes covering an area of 222.8 ha during 1980. The number and area under these lakes increases afterward and reached up to 783 having 955.6 ha area in 2017. There were 253 glacial lakes with total area of 414 ha during 1990, 370 with total area of 654.4 ha for 2000, 588 with total area of 717.6 ha for 2010. It was observed that some of the lakes were appeared and some disappeared during the study period however, appearance was prominent in higher elevation ranges (4000–5500 m) making it potentially vulnerable altitude zone for GLOFs. The study provided base for further monitoring of the lake dynamics and recognize possible GLOF prone areas which is valuable information for the policy makers involved in the social engineering of hill habitants and researchers across the globe.