The floods that crashed into two hydroelectric plants and caused damage to the villages of northern India were caused by a break in the Himalayan glacier upstream. Here’s a look at how glaciers and glacial lakes form and why they can sometimes break:
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HOW GLACIERS AND GLACIAL LAKES FORM
Glaciers are found on every continent except Australia and some are hundreds of thousands of years old. A large cluster of glaciers is located in the Himalayas, which is part of the long northern border of India. Sunday’s disaster occurred in the western part of the Himalayas.
Glaciers are made up of layers of compressed snow that move or “flow” due to the gravity and softness of the ice relative to the rock. The “tongue” of a glacier can extend hundreds of miles from its origins at high altitude and the end, or “snout,” can move forward or backward depending on the accumulation or melting of snow.
“Ice can flow through mountain valleys, deviate through the plains or in some places, to extend into the sea,” according to the National Snow and Ice Data Center.
Proglacial lakes, formed after the retreat of glaciers, are often joined by sediment and pebble formations. Additional water or pressure or structural weakness can cause natural and artificial dams to burst, surrounding a mass of floodplain that flows down glacier-fed rivers and streams.
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WHY DID THIS GLACIER BREAK?
It is not yet known what caused part of the Nanda Devi Glacier to explode on Sunday morning, causing the floodwaters to grow downstream towards power plants and villages in northern India, Uttarakhand.
Seismic activity and water pressure buildup can cause glaciers to erupt, but a particular concern is climate change. High temperatures, along with less snowfall, can accelerate melting, causing water to rise to potentially dangerous levels.
“Most of the world’s mountain glaciers were much larger in the past and have been melting and shrinking drastically due to climate change and global warming,” said Sarah Das, an associate scientist at the Woods Hole Oceanographic Institute. .
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CAN SUCH DISASTERS BE FORECASTED?
Deadly or highly destructive glacial floods have occurred in Peru and Nepal.
But the remote locations of glaciers and the lack of surveillance make us not have a clear understanding of how often they occur and if they increase, Das said.
“Given the general pattern of warming, glacier retreat, and increased infrastructure projects, it seems natural to hypothesize that these events will occur more frequently and will generally be more destructive if no measures are taken to mitigate these risks. “, has said .
Several imminent potentially deadly glacier explosions and flooding situations have been identified around the world, including the Himalayas and the South American Andes.
But while control is possible, the distance from most glaciers presents challenges.
“There are many glacial reservoirs and glacial reservoirs throughout the Himalayas, but most are not controlled,” Das said. “Many of these lakes are found upstream of steep river valleys and can cause extreme flooding when they break. Where these floods reach inhabited areas and sensitive infrastructure, things will be catastrophic.”
An information page from 2010 published by the International Center for Integrated Mountain Development, increased monitoring of glaciers in the Himalayas of the Hindu Kush was called for to better understand “the real degree of instability of the glacial lake”.
The region where the glacial eruption occurred is prone to landslides and rapid flooding, and environmentalists have warned that they should not be built in the region.
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The Associated Press Health and Science Department is supported by the Howard Hughes Medical Institute’s Department of Science Education. The AP is solely responsible for all content.