Geoinformatics Perspective of Landslide and Catastrophic Flash Floods in Dhauliganga, Uttarakhand, India

On 07 February 2021, around 10:30 hrs local time catastrophic flash flood occurred in the Dhauliganga River (a tributary of Ganga River) near Rini village at 2000 m above MSL (mean sea level) (Chamoli District), which killed 79 people and about 125 were missing. Part area belongs to Nanda Devi Biosphere Reserve, is completely protected from human interventions. Further, on River, two run-of-river hydroelectric power Rishiganga Small Hydro (13.2 MW) 1975 Tapovan Vishnugad (520 1795 projects also severely damaged due devastating flood. More than 150 workers trapped under-construction tunnel project. Initial assessment day event suggested that there was a glacial burst. Later, it evaluated through series high spatial resolution remote sensing images various satellites large part north-facing triangular-shaped slope 5540 had failed, supporting small hanging glacier. This landslide and, consequently, massive debris flow into Raunthi Gadhera initially blocked [at level)], later failed 2021 brought river. acquired 10:33 revealed dust cloud clearly unravels sequence events high-altitude landslide, collapse glacier, snow avalanche flooding. Even after an elongated lake created blocking Rishi River. For detailed analysis, calculation dimension, volume done using high-resolution satellite digital elevation model RAMMS modelling technique. The triangular shape base 660 1100 height estimated total calculated 20 million cubic meters, including rocks, snow, ice. runout simulation performed calculate depth, velocity maximum pressure. Also, images, dimensions artificial Lake have length 800 m, width front 100 depth 46m, freshly deposited silt 10 m. To lake, ArcView software model, came out be ~5 meters. paper emphasizes monitoring such vulnerable areas based are available regular basis avoid loss lives future.