Uttarakhand is infamous for natural disasters because most parts of the state are covered by Himalayan peaks and glaciers. Since the Himalayas were only formed 40 - 50 million years ago, tectonic activities like thrusts, faults and plate collisions are common, making the state sensitive and prone to natural disasters. The adverse geological setting makes the state highly prone to intense earthquakes, cloudbursts, flash floods, and landslides.
What is a glacier break? Why does a glacier break?
The geographic term for a glacier break is Glacial Lake Outburst Flooding (GLOF.) It refers to a sudden release of a massive amount of water held in a glacier lake.
When glaciers melt, they form glacial lakes which are often bound only by sediments and boulders. Now imagine, even if a few massive chunks of glaciers break and fall into the lake, it will not only increase the volume of water in the lake, but also increase pressure. This would lead to large amounts of water rushing down to nearby streams and rivers, gathering momentum on the way by picking up sediments, rocks and other material, and resulting in flooding downstream.
Since the southern division of Chamoli district consists of mountains that are composed of sedimentary rocks, when a large volume of water comes down at such a massive speed, it will wash away sediments, rocks, and boulders. It will cause massive erosion and landslides, washing any kind of man-made infrastructure like dams, hydro power projects, houses, and villages.
There are speculations about whether the current flood was triggered by a glacial lake burst or a landslide. Many experts are currently looking into it.
What are the causes of the disaster?
While GLOF is being considered the most likely trigger, there are questions around this possibility.
Professor H C Nainwal, a glaciologist from the Hemwati Nandan Bahuguna Garhwal University in Srinagar, Uttarakhand says, “We don’t know of any big glacial lakes in this region. An avalanche is quite common, and there could have been one, but an avalanche on its own would not result in an increase in the flow of water in the river. The water has to come from a source, and as of now, we do not know what this source is.”
Argha Banerjee, a glaciologist who works at the Indian Institute of Science Education and Research Pune said, “there are hundreds of such lakes all over the place. We know about many of them, but it is possible that there is one that we do not know about. After today’s event, I started looking at the satellite images, and I couldn’t find any glacial lake in that area. But maybe, if we look at higher resolution satellite images, we would find one.” He added that there have been instances of lakes forming inside the glaciers which cannot be detected through satellite images.
“But if there are indeed no glacial lakes in that area, then Sunday’s event would seem to be a bit of a surprise,” he said. The surprise comes also because of timing. Cloudburst, a possible reason for the sudden rush of water is not expected during this time of the year. .
“It is possible that an avalanche or a landslide created an obstruction in the flow of the river or streams in the upper mountains, resulting in a makeshift dam-like situation. When the pressure of the flowing water became large, the dam probably gave away, leading to a sudden gush of water. These are just the possible scenarios.” Banerjee said.
Then there are also other issues to consider such as climate change or disproportionate construction in a fragile geographic region, factors which contributed significantly to the 2013 disaster. As of now, the event does not seem to have any direct linkage to construction-related activities, or big dams, but climate change as a factor can not be ignored, particularly in the formation of proglacial lakes like those in the Himalayas.
Does global warming have anything to do with this?
Yes. Since the 1900s, glaciers across the world have been rapidly melting. Environmental experts have attributed glacial melt to global warming. Glacier retreat is projected to decrease the stability of mountain slopes and increase the number and area of glacier lakes, according to the assessment reports of the UN Intergovernmental Panel on Climate Change.
The exact cause of the incident will only be revealed after investigation. However, until then it may be helpful to consider the ramifications of a rapidly changing climate on earth.
Chat
Comments