On June 17, 2013, a major disaster struck one of the country's most sacred destinations - the holy pilgrimage site of Kedarnath. The town was almost washed away, with thousands drowned, injured, and many gone missing in the raging floodwaters that swept through the town. The cause of this disaster was a glacial lake outburst flood (GLOF) involving the Chorabari Lake. The frightening news is that scientists predict that the chances of such GLOFs will rise in the future, primarily due to global warming-induced climate change.
Here is a detailed post on the term and how and why such events can multiply in the future.
What Is A Glacial Lake?
A glacial lake is one whose formation is associated with a glacier or glacial activity. Most glacial lakes are formed when glaciers retreat and leave behind the meltwater filling the depressions eroded by glacial activity over time. Depending on how the natural dams that withhold water in the lakes are formed, such lakes can be moraine-dammed, ice-dammed, bedrock-dammed, or landslide/avalanche dammed.
The Lake That Died
The Chorbari Lake was a moraine-dammed glacial lake of untamed beauty at the foot of the Chorabari Glacier in Uttarakhand, India. It was located at an elevation of 3,960 m, about 2 km upstream of Kedarnath, and was part of the Mandakini river basin.
The lake, glacial in origin, formed from meltwater at the mouth of the Chorabari Glacier. However, over time, it became cut off from the glacier as the glacier retreated due to warming temperatures induced by climate change. Deposits between the lake and the glacier further isolated it. A moraine at the end of the lake, deposited in the past due to glacial activity, acted as a natural dam holding the lake's waters in place. The lake had a length of 250 m and a width of 150 m and was around 15 to 20 m deep. Rainwater and snowmelt then became the water source in the Chorabari Lake, whose water volume varied with seasons and changing precipitation levels each year.
Another interesting fact about the lake is its connection with Mahatma Gandhi. A part of his ashes was immersed in the lake's waters, giving it the name Gandhi Sarovar. Because of this association with Gandhi, people would often trek to see the lake.
The Fateful Day
In June 2013, Uttarakhand received incessant rainfall, which was estimated to be 375% of what it normally receives during that time of the year. The rainfall caused the Chorabari glacier to melt in places and become unstable. The Chorabari Lake was already filling up with rainwater, which put immense pressure on its natural moraine embankment. The lake's level rose by 7 m or 23 feet during this time!
On June 17, an avalanche in the glacier triggered by incessant rain caused the ice with rocks and other debris to slide into the Chorabari Lake. This sudden rise in volume was too much for the moraine dam. It crumbled and the entire lake emptied itself downstream, carrying with it around 262 million litres of water, massive boulders, and other debris. Within 5 to 10 minutes, the Chorabari Lake was empty. The lakewater entered the Mandakini, swelling it up and lashing its fury on the towns that lay below.
Over 6,000 people died, and many went missing forever. Of course, there is no mention of the many animals that were wiped out as well.
The Beginning Of The End?
In the aftermath of the disaster, Kedarnath was secured by a three-tiered wall behind the temple, strengthened embankments of the Mandakini River, and then rebuilt.
The Chorabari Lake died—today, it is just a trickle of water flowing through the broken embankment area. Scientists predict that it will take at least a century before the lake fills up with water again. This will only happen if the embankment is plugged again by some event like a major landslide or avalanche.
Despite this threat being eliminated, other lakes in the region could burst in the future as more and more new such lakes are to form as glaciers retreat and leave them behind.
The root cause behind all this is global warming-induced climate change. It is causing glaciers to retreat and unpredictable weather events like excessive rainfall and snowstorms to become more common.
So, while the Kedarnath Valley is safe from the Chorabari Lake for now, GLOF's related to other lakes, river flooding due to excessive rainfall, major avalanches, and earthquakes all threaten the future of this popular pilgrimage site.
Hence, it is important for authorities to reduce the anthropogenic impacts on the valley as much as possible to ensure that any future disasters have minimal impact on lives.
Not just the Kedarnath Valley but the entire stretch of the Himalayas is currently facing the risk of a GLOF. Millions of lives are at risk. As people worldwide contribute to climate change, the world as a whole will be responsible for such tragic events in the coming times.
Read more:
https://dialogue.earth/en/climate/death-of-chorabari-lake/
https://eos.org/articles/millions-in-india-vulnerable-to-glacial-lake-floods
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