A devastating flood in northern India’s Uttarakhand state killed at least 32 people and arrested workers in underground tunnels. It also sparked speculation about what caused Sunday’s flood.
Did an avalanche burst a glacial lake? Or could an avalanche or landslide have dammed a river for some time, causing it to overflow? Or did the ice blocks break through a glacier due to the rise in temperature?
Rescue efforts are still ongoing, with more than 170 people missing – 12 workers were pulled out of a tunnel after being trapped in the freezing darkness.
Now, a team of scientists investigating the incident believes that a piece of a Himalayan glacier fell into the water and triggered the massive flooding in Uttarakhand state.
A glacier is a river of ice that flows slowly, accumulating snow, rock, sediment and often liquid water.
Five scientists flew over the glacier in a helicopter, took pictures, looked at satellite photos and collected data from the devastated area.
The origin of the incident, they say, was a glacier at a remote and inaccessible 5,600 m (18,372 ft) peak called Raunthi.
Scientists believe that part of this glacier was rolled up and hung on a slope, supported by a mass of rock. This part weakened over time due to freezing and melting.
That piece of ice and rock broke on Sunday and was launched down a steep mountain slope, they say.
When it reached the bottom of a valley, they believe that its rocks, snow and sediment fell into a relatively narrow mountain stream at a height of 3,600 m, blocking it.
As the water level increased in the stream, it exploded. A wave of water and debris descended further, breaking the dam and causing massive flooding downstream. Water, gravity and geology conspired to create confusion, leading to countless deaths and leaving hundreds in danger.
“What we found is not very common. The weakening of the ‘suspended’ glacier must have happened over a long period of time as the ice froze and melted,” Dr. Kalachand Sain, director of the Wadia Institute in the Himalayas, based in Dehradun Geology , who sent the team of scientists, told the BBC.
Climate change, he said, is the “main factor” for rapid changes in temperature that lead to freezing and thawing of ice and glacial fractures over time. Glaciers accumulate snow in winter and lose snow in summer. But when temperatures rise, they lose ice faster than they can collect it. Melting ice can lead to glaciers receding.
There are about 10,000 glaciers in the Indian Himalayas. Uttarakhand has up to 1,495 glaciers and many are decreasing due to the warming climate. “If something as unusual as what happened on Sunday occurs in 10% of our glaciers, the danger to life and property will be immense,” said Sain.
Clearly, India needs more surveillance of glaciers.
