A catastrophic flood occurred on 7 February 2021 around 10:30 AM (local time) in the Rishiganga River, which has been attributed to a rockslide in the upper reach of the Raunthi River. The Resourcesat 2 LISS IV (8 February 2021) and CNES Airbus satellite imagery (9 February 2021) clearly show the location of displaced materials. The solar radiation observed was higher than normal by 10% and 25% on 6 and 7 February 2021, respectively, however, the temperature shows up to 34% changes. These conditions are responsible for the sudden change in instability in glacier blocks causing deadly rock-ice slides that led to the collapse of the hanging glacier as a wedge failure. The displaced materials mixed with ice, snow, and debris caused catastrophic floods downstream within no time that destroyed critical infrastructure and killed human lives. The hydrodynamic modelling (HEC-RAS software) shows mean flow velocity up to 22.4 ± 8.6 m/s with an average depth of 16.3 ± 6.5 m that caused deadly devastation in the source region and along the rivers due to the flow of water in the valley.
Vijendra Kumar Pandey, Rajesh Kumar, Rupendra Singh, Rajesh Kumar, Suresh Chand Rai, Ramesh P. Singh, Arun Kumar Tripathi, Vijay Kumar Soni, S. Nawaz Ali, Dakshina Tamang & Syed Umer Latief (2022) Catastrophic ice-debris flow in the Rishiganga River, Chamoli, Uttarakhand (India), Geomatics, Natural Hazards and Risk, 13:1, 289-309, https://doi.org/10.1080/19475705.2021.2023661
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This article was originally published in Geomatics, Natural Hazards and Risk, volume 13, issue 1, in 2022. https://doi.org/10.1080/19475705.2021.2023661