Hanging glacier avalanche (Raunthigad–Rishiganga) and debris flow disaster on 7 February 2021, Uttarakhand, India: a preliminary assessment

This paper is a preliminary assessment of the glacier avalanche and debris flow disaster that occurred on 7 February 2021 in Uttarakhand, India. The researchers make some observations on the causes and effects of the particular disaster. Role of precipitation, snow cover, land surface temperature, and permafrost processes were investigated for identifying causes of the event. Since 2012, monsoon precipitation and mean annual land surface temperature (LST) showed significant increasing trend. Snow cover during monsoon months showed increasing trend and September, October and November experienced decreasing trend at glacier elevations.

It is suggested that the increase in summer precipitation might have forced thickening of the accumulation area and thereby increasing the shear stress for sliding of the glacier. It is proposed that the recent change in the weather conditions in the region is primarily responsible for this event through geological, glaciological, and permafrost processes. The event highlighted the need for improved monitoring of the cryosphere areas of the Himalaya to capture the early warning signs for better preparedness. System response is building over a period of time due to increased summer precipitation, elevation-depended snow cover change, warming of land surface exacerbated by the seasonal response of reduced snow cover. Delayed response of deeper ground to surface warming, mass balance fluctuations due to increase in summer precipitation, etc. This added a new disaster component in the Himalaya, warranting its regular monitoring at least in the area surrounding infrastructure or development projects, including tourism areas.