How Glaciers Can Burst and Cause Flooding
2021-02-09
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1Indian rescuers searched on Monday for about 200 people missing after part of a Himalayan glacier broke away Sunday and caused major flooding.
2The flooding happened when part of the Nanda Devi glacier broke off, releasing water trapped behind it.
3The burst sent floodwater toward power plants and villages in northern Uttarakhand state.
4The floods destroyed bridges and broke dams.
5Huge amounts of water, rock and building materials flowed down a mountain valley.
6At least 26 people are confirmed dead.
7More than 2,000 military members, police officers and others have been taking part in search-and-rescue operations.
8Most of the missing were people working on two hydroelectric power plants.
9The projects are part of government efforts to develop the mountainous areas of Uttarakhand state.
10The floodwaters rushed down the mountain and into other bodies of water.
11Many villages along the Alaknanda and Dhauliganga rivers were evacuated.
12The two rivers flow out of the Himalayan mountains and later join with the Ganges River.
13Videos on social media show the muddy, gray floodwaters quickly flowing through a valley and into a dam, and breaking it into pieces before continuing downstream.
14Experts said the disaster could be linked to climate change.
15A team of scientists was flown to the area Monday to investigate what happened.
16A glacier is a very large area of ice that moves slowly down a mountainside or valley or over a wide area of land.
17Glaciers are made of closely formed layers of snow.
18They move or flow because of gravity and the softness of ice compared to rock.
19A long and narrow piece of ice called a glacier's "tongue" can extend hundreds of kilometers from its beginnings in high mountains.
20The end of the tongue can advance or move backward based on snowfall and melting.
21Bodies of water called proglacial lakes are formed after glaciers retreat, or move back.
22Extra water or pressure -- or structural weakness -- can cause both natural and manmade dams to burst.
23This sends a mass of floodwater flowing down the rivers fed by the glacier.
24It is not yet known what caused part of the Nanda Devi glacier to break off.
25Seismic activity and a buildup of water pressure can cause glaciers to burst.
26But climate change may be another cause.
27High temperatures, combined with less snowfall, can increase the speed of melting.
28This causes water to rise to possibly dangerous levels.
29Sarah Das is a scientist at Woods Hole Oceanographic Institute in Massachusetts.
30She told The Associated Press, "Most mountain glaciers around the world were much larger in the past and have been melting and shrinking dramatically due to climate change..."
31Sunday's disaster happened in the western part of the Himalayas.
32The mountains form part of India's long northern border.
33A 2010 information page published by the International Centre for Integrated Mountain Development called for more glacier observation in the Himalayas to better understand "the real degree of glacial lake instability."
34The area where the glacial burst took place experiences landslides and flooding.
35Environmental experts have warned against building in the region.
36I'm Ashley Thompson.
1Indian rescuers searched on Monday for about 200 people missing after part of a Himalayan glacier broke away Sunday and caused major flooding. 2The flooding happened when part of the Nanda Devi glacier broke off, releasing water trapped behind it. The burst sent floodwater toward power plants and villages in northern Uttarakhand state. The floods destroyed bridges and broke dams. Huge amounts of water, rock and building materials flowed down a mountain valley. 3At least 26 people are confirmed dead. 4More than 2,000 military members, police officers and others have been taking part in search-and-rescue operations. 5Most of the missing were people working on two hydroelectric power plants. The projects are part of government efforts to develop the mountainous areas of Uttarakhand state. 6The floodwaters rushed down the mountain and into other bodies of water. Many villages along the Alaknanda and Dhauliganga rivers were evacuated. The two rivers flow out of the Himalayan mountains and later join with the Ganges River. 7Videos on social media show the muddy, gray floodwaters quickly flowing through a valley and into a dam, and breaking it into pieces before continuing downstream. 8Experts said the disaster could be linked to climate change. A team of scientists was flown to the area Monday to investigate what happened. 9How glaciers and glacial lakes are formed 10A glacier is a very large area of ice that moves slowly down a mountainside or valley or over a wide area of land. Glaciers are made of closely formed layers of snow. They move or flow because of gravity and the softness of ice compared to rock. 11A long and narrow piece of ice called a glacier's "tongue" can extend hundreds of kilometers from its beginnings in high mountains. The end of the tongue can advance or move backward based on snowfall and melting. 12Bodies of water called proglacial lakes are formed after glaciers retreat, or move back. Extra water or pressure -- or structural weakness -- can cause both natural and manmade dams to burst. This sends a mass of floodwater flowing down the rivers fed by the glacier. 13Why did this glacier burst? 14It is not yet known what caused part of the Nanda Devi glacier to break off. 15Seismic activity and a buildup of water pressure can cause glaciers to burst. But climate change may be another cause. High temperatures, combined with less snowfall, can increase the speed of melting. This causes water to rise to possibly dangerous levels. 16Sarah Das is a scientist at Woods Hole Oceanographic Institute in Massachusetts. She told The Associated Press, "Most mountain glaciers around the world were much larger in the past and have been melting and shrinking dramatically due to climate change..." 17Sunday's disaster happened in the western part of the Himalayas. The mountains form part of India's long northern border. 18A 2010 information page published by the International Centre for Integrated Mountain Development called for more glacier observation in the Himalayas to better understand "the real degree of glacial lake instability." 19The area where the glacial burst took place experiences landslides and flooding. Environmental experts have warned against building in the region. 20I'm Ashley Thompson. 21Ashley Thompson adapted this story based on reports by The Associated Press and Reuters news agency. Hai Do was the editor. 22______________________________________________________________ 23Words in This Story 24glacier - n. a very large area of ice that moves slowly down a slope or valley or over a wide area of land 25hydroelectric - adj. of or relating to production of electricity by waterpower 26rush - v. to move very quickly 27evacuate - v. to remove (someone) from a dangerous place 28muddy - adj. filled or covered with mud (soft, wet dirt) 29layer - n. a covering piece of material or a part that lies over or under another 30advance - v. to move forward 31seismic - adj. of, relating to, or caused by an earthquake 32dramatically - adv. sudden and extreme 33due to - adj. because of 34instability - n. the state of being likely to change 35region - n. a part of a country, of the world, etc., that is different or separate from other parts in some way 36We want to hear from you. Write to us in the Comments section, and visit our Facebook page.