Scientists are not yet sure what caused the glacier burst at Uttarakhand. Was it the avalanche or the impact of climate change? People are trying to figure out what triggered the very sudden surge of water near Chamoli in Uttarakhand on Sunday morning. It is said that it has made people recall the 2013 disaster that happened in the state.
By evening, the prospect of largescale flooding and destruction had receded. And, as scientists prepared to travel to the site in the high mountains north of Chamoli to ascertain the cause of the incident, the scenario being most talked about was what glaciologists like to call a GLOF or glacial lake outburst flood. It is a reference to flooding caused downstream due to a breach in a glacial lake.
Retreating glaciers, like several in the Himalayas, usually result in the formation of lakes at their tips, called proglacial lakes, often bound only by sediments and boulders. If the boundaries of these lakes are breached, it can 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.
GLOF events are not unusual, but their impact depends on the size of the Proglacial Lake that burst, and its location. The breach can be caused by several reasons — in this particular case, for instance, an avalanche was reported in the region two days ago
But while GLOF is being considered to be the most likely trigger for Sunday’s event, there are questions surrounding this possibility. “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,” said Professor H C Nainwal, a glaciologist at the Hemwati Nandan Bahuguna Garhwal University in Srinagar, Uttarakhand.
“We would have to visit the area to find out what exactly happened. Till then, we can only speculate,” he said.
What scientists are almost certain of is that the incident was not a result of any glacier ‘breaking off’. In fact, glaciers are not known to break in a manner that ice-sheets in the Polar Regions do. Some chunks of snow from near the tip of the glacier can indeed slide down, but they do not result in huge amounts of water like those seen in incidents like these.