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Topics Covered: Disaster management.
Chamoli disaster due to avalanche:
Context:
Flash flood on February 7 in Chamoli district, Uttarakhand, claimed at least 72 lives with at least 200 missing. Now, Geological Survey of India (GSI) has submitted its report on causes of the disaster.
Key findings:
- Flash flood was due to a large mass of snow, ice and rock avalanche along with a hanging mass of rock crashing into the Raunthi Garh valley floor.
- This impact pulverised the combination of rock, snow and ice causing a rapid flow downstream of Raunthi Garh and into the Rishiganga valley leading to the deluge.
- A contributory factor was unusually warm weather in the region.
- There was no evidence of a Glacial Lake Outburst Flood (GLOF) having caused the event.
What happened on February 7th?
A glacial break in the Tapovan-Reni area of Chamoli District of Uttarakhand led to massive Flash Flood in Dhauli Ganga and Alaknanda Rivers, damaging houses and the nearby Rishiganga power project.
What is glacial lake outburst flood (GLOF)?
It is an outburst that happens when a dam containing a glacial lake fails.
GLOFs have three main features:
- They involve sudden (and sometimes cyclic) releases of water.
- They tend to be rapid events, lasting hours to days.
- They result in large downstream river discharges (which often increase by an order of magnitude).
Why does a glacier break?
- Erosion.
- A build-up of water pressure.
- An avalanche of snow or rocks.
- An earthquake under the ice.
- Massive displacement of water in a glacial lake when a large portion of an adjacent glacier collapses into it.
Insta Curious:
Do you know what pelean eruption is? Read Here
InstaLinks:
Prelims Link:
- About GLOF.
- About Alaknanda river.
- About Dhauli Ganga.
- About Rishiganga river project.
Mains Link:
How is India prepared for disasters posed by glacial lake outburst flood (GLOF)? Discuss.
Sources: the Hindu.
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