The Chamoli Disaster is what the Flash Floods that occurred on 7th February 2021 in the outer Garhwal Himalayas within the mountainous state of Uttarakhand, India is commonly known as.
Imagine being hit by a flowing mass of rock hurtling at 90 kilometers/hour (56 mph) - some of the boulders within were more than 20 metres in diameter!
The 13.2 MW Rishiganga Small Hydro Project situated at 15 kilometers elevation was obliterated like a deer in headlights. The debris-laden mass greeted the larger 520 MW Tapovan-Vishnugad Hydro Project 10 kilometres downhill at a speed of 60 kilometres/hour (37 mph), malevolent enough to severely damage an under-construction Power Plant within, blocking its tunnels, and fatally trapping 140 workers at the site. In all, 204 people perished to this calamitous tragedy along with 20 hectares of forest, bridges, critical infrastructure and residential settlements.
While the floods settled down, news reports were brewing with theories about what caused this calamity - Glacier Burst, Landslide etc. The root cause was ascertained last month (10th June 2021) by a group of 53 researchers who published their findings in the renowned academic journal Science and subsequently, researchers from Geological Survey of India reached the same conclusion (29th June).
The Flash Floods were triggered by a Rock and Ice Avalanche formed from the sudden collapse of a massive Glacier-covered Rock 1500 metres long, 500 metres wide and 180 metres thick on the steep northern face of the 5600 metres-tall Ronti (Raunthi) mountain.
The Glacier-covered Rock had a free fall for much of its initial 2 kms descent. When the estimated 27 million cubic metres of material comprising 80% rock and 20% ice hit the valley floor (Ronti Gad), the energy released was equivalent to the detonation of 15 Hiroshima Atomic Bombs! - this melted the snow instantaneously, creating a highly mobile mass of water and debris which wreaked havoc till a full 35 kilometers downstream, including the two ill-fated hydropower projects.
This BBC article presents a detailed account of the Chamoli Disaster and it prompted me to inspect the source of the Avalanche myself - my findings extracted from Sentinel-2 Optical Satellite Imagery has been captured in this video and in the two Sliders attached subsequently in this post-
Slider 1: Source View as on 21st May 2020 (1 year prior) and 5th February 2021 (2 days prior)
Slider 2: Source View as on 5th February 2021 (2 days prior) and 31st May 2021 (~4 months later)
One can't help but think what a different situation it would have been had someone been monitoring Ronti's peak prior to 7th February 2021. So many precious lives could have been saved.
“Hindsight is a wonderful thing but foresight is better, especially when it comes to saving life, or some pain!” - Quote by William Blake.
In perspective, this is not a far-fetched idea. Displacement of the Glacial Rock on Ronti's peak was detected as early as 2016. Besides, the wisdom of developing Critical Infrastructure projects in fragile terrains has repeatedly been questioned by experts and the least one could have in place is an Early Warning System (EWS) from a Risk Management point-of-view. The history of Uttarakhand is replete with instances of Floods, Forest Fires and Landslides and the two destroyed Hydropower Plants have been impacted by floods on several occasions historically. If you were to read this article written by Sunita Narain - a member of an inter-ministerial group assessing issues related to the Ganga river - you'll be left aghast at the sinister designs of all those involved in the planning and sanctioning of Hydropower Projects in the state of Uttarakhand where all the five headstreams of the river Ganges, a lifeline for 650 millions riverside dwellers, reside.
It is also important to recognize the role that Climate Change played in this disaster - January 2021 was the warmest January in Uttarakhand in six decades and heavy snowfall was followed by sudden warm temperatures between 4th and 6th February 2021. These would have contributed to the weakening of the Glacier Rock's binding to Ronti's Mountain face, culminating in the tragic sequence of events on 7th February 2021.
The unfortunate aspect is that while terabytes of Satellite Imagery are acquired every day, a majority of it escapes human attention - this is where the utility of automated detection and classification algorithms comes to the fore.
Access more of my independent Remote Sensing work here.
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