Context
A part of the Nanda Devi glacier broke off in Uttarakhand's Chamoli district. Though the reason is not sure, it could be a glacial lake burst, a cloud burst or an avalanche, the impact of climate change or development.
Glacial lake outburst flood (GLOF)
- It is a reference to flooding caused downstream due to a breach in a glacial lake.
- Retreating glaciers result in the formation of lakes at their tips, called pro-glacial lakes, often bound only by sediments and boulders.
- If the boundaries of these lakes are breached, it can lead to large amounts of water rushing down to nearby streams and rivers.
- GLOF events impact depends on the size of the proglacial lake that burst, and location.
Proglacial lakes
- A proglacial lake is a lake formed by
- damming action of a moraine during the retreat of a melting glacier
- a glacial ice dam
- by meltwater trapped against an ice sheet due to isostatic depression of the crust around the ice.
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Reasons behind GLOF
The breach can be caused by several reasons:
- Erosion
- The buildup of water pressure
- Avalanche of rock or heavy snow
- Earthquake or Cryoseism
- Volcanic eruptions under the ice.
