Geospatial technology-based monitoring of HAGL in the context of flash flood: A case study of Rishi Ganga Basin, India

This study, motivated by the flood disaster that took place at the glaciated region in Rishi Ganga Basin of Nanda Devi Biosphere Reserve (NDBR), Uttarakhand on 7th February 2021, intends to identify the altitudinal and sequential changes in the glacier region using satellite imageries. Our results suggest that 21.50 km2 and 34.70 km2 glacier area was lost from the region during the period 1976–2013 and 1976–2020 respectively. Besides this, out of the 106 High Altitude Glacial Lakes (HAGLs) found at an altitude of 4500 m above mean sea level (amsl), 14 potential spots are identified which can be a reason for future calamities. Our analysis of snow cover extents for the decade 2010–2021 suggests a considerable decrease of (16–28%) in winter snow cover. The unpredictable temperature fluctuations especially during the last few decades have also affected the freezing and thawing processes in the high-altitude areas. The changing behavior of the weathering processes quite often results in landslides, a major reason for disasters in the higher Himalaya. There is, thus, an urgent need to identify the high-risk sites in higher Himalaya which may be potential zones for future landslides. In anticipation to mitigate the resulting damages, the study emphasizes developing an early warning system based on geospatial technology to minimize loss of life, particularly for the workers employed in the engineering projects in the vicinity of the risk zone.