The floods that hit two hydropower plants and damaged towns in northern India were shot down by an interruption on a Himalayan glacier upstream. Here’s a look at how glaciers and glaciers form and why they can sometimes break:
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HOW ADVANCES AND SYSTEMS FORM
Glaciers are found on every continent except Australia, and some are hundreds of thousands of years old. A large group of glaciers are in the Himalayas, which are part of the long northern border of India. Sunday’s disaster occurred in the western part of the Himalayas.
Glaciers are made of layers of compressed snow that move or ‘flow’ due to gravity and the softness of ice relative to rock. A glacier ” tongue ‘can extend hundreds of kilometers (miles) from its source at great height, and the end, or’ snout ‘, can move or retreat due to snow accumulating or melting.
“Ice can flow from mountain valleys, blow across plains or spread to the sea in some places,” according to the National Snow and Ice Data Center.
Proglacial lakes, formed after glaciers retreat, are often bound by sediment and rock formations. Additional water or pressure, or structural weakness, can cause both natural and man-made dams to burst, causing a mass of floodwater to flow into the rivers and streams flowing through the glacier.
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WHY THIS GLASS BREAST?
It is not yet known what caused part of the Nanda Devi Glacier to collapse on Sunday morning, causing the floodwaters to flow downstream to power stations and towns in the northern state of Uttarakhand of India.
Seismic activity and the build-up of water pressure can cause glaciers to burst, but particular concern is climate change. High temperatures coupled with less snowfall can accelerate the melting, causing water to rise to potentially dangerous levels.
“Most mountain glaciers around the world have been much larger in the past and have melted and shrunk dramatically due to climate change and global warming,” said Sarah Das, a fellow scientist at Woods Hole Oceanographic Institute.
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CAN such disasters be predicted?
Previous deadly or extremely devastating glacial floods have occurred in Peru and Nepal.
But the remote locations of glaciers and a lack of monitoring mean we do not have a clear understanding of how often they occur and whether they increase, Das said.
However, given the overall pattern of warming, glacier retreat and increase in infrastructure projects, it seems natural to assume that these events will occur more frequently and will generally become more destructive if no measures are taken to reduce these risks. not, “Das said. .
A number of threatening potentially deadly glacier bursts and flood situations have been identified worldwide, including in the Himalayas and South American Andes.
But while monitoring is possible, the distance from most glaciers presents challenges.
“There have been many glaciers and more with glaciers dammed over the Himalayas, but most have not been monitored,” Das said. ‘Many of these lakes are upstream of steep river valleys and can cause extreme flooding if they break. Where these floods reach inhabited regions and sensitive infrastructure, things will be catastrophic. ”
An information sheet for 2010 published by the International Center for Integrated Mountain Development, called for more monitoring of glaciers in the Hindu-Kush Himalayas to better understand ‘the real degree of instability in the glacial lake’.
The region where the icebreaking occurred is prone to landslides and avalanches, and environmentalists have warned not to build in the region.
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