Unraveling the geological and meteorological interplay during the 2021 Chamoli disaster, India

Abstract

Chamoli district of Uttarakhand, India, witnessed unprecedented damage to life, property, infrastructure, and landscape due to flash flood triggered on 7th February 2021. During winters, massive debris flow in the Raunthi Gad catchment put a great ambiguity on disaster preparedness. Sustained heavy precipitation for the two days prior to the event and wedge failure structural favorability might have aided the landslide and triggered rock-avalanche. Due to the landslide, the impounding of the river waters resulted in temporary dam creation in the Rishiganga valley, which ultimately led to the breaching. By coupling the data obtained from satellite imagery, characteristic scientific case studies and reports, it can be inferred that the most possible cause is the interplay of extreme meteorological phenomena and particular geological scenarios including the formation of wedge geometry by the intersection of joint and foliation planes in migmatite and tension cracks at crown of slope. Critical reviews over extreme furry of nature and terrain response have also been discussed.