The floods that hit two hydroelectric power plants and damaged villages in northern India were triggered by a rupture on a glacier in the Himalayas upstream. Here’s 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 group of glaciers is located in the Himalayas, which are part of the long northern border of India. Sunday’s disaster occurred in the western Himalayas.
Glaciers are composed 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 kilometers (miles) from its origins at high altitude, and the end or “snout” can advance or retreat based on the accumulation or melting of snow.
“Ice can flow on mountain valleys, spread over plains or in some locations, spread over the sea,” according to the National Data Center for Snow and Ice.
Proglacial lakes, formed after the retreat of glaciers, are often associated with sediment and boulder formations. Water or additional pressure or structural weakness can cause both natural and man-made dams to erupt, sending a body of flood water flowing into rivers and glacier-fed streams.
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WHY DID THIS GAZER FUCK?
It is not yet known what caused part of the Nanda Devi Glacier to catch on Sunday morning, sending floodwaters rising upstream to power plants and villages in the northern Indian state of Uttarakhand.
Seismic activity and the accumulation of water pressure can cause the explosion of glaciers, but a special concern is climate change. High temperatures, combined with less snow, can accelerate 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, an associate scientist at 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 monitoring mean we don’t have a clear understanding of how often they occur and how they grow, Das said.
“Given the general pattern of warming, the retreat of glaciers and the growth of infrastructure projects, however, it seems natural to assume that these events will occur more frequently and will generally become more destructive if no measures are taken to mitigate these risks. Said Das.
A number of potentially deadly situations of explosion and glacier flooding have been identified worldwide, including in the Himalayas and the South American Andes.
But while monitoring is possible, removing most glaciers is challenging.
“There are many glaciers and glacial dam lakes along the Himalayas, but most are unmonitored,” Das said. “Many of these lakes are upstream of steep river valleys and have the potential to 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 called for greater monitoring of glaciers in the Hindu Kush Himalayas to better understand the “real degree of instability of the glacial lake.”
The region where the glacial explosion took place is prone to landslides and rapid floods, and environmentalists have warned against building in the region.
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