Context:
Glacial lakes rise as glaciers retreat owing to global warming.
Glacial Lake Outburst Flood (GLOF):
- Glacial Lakes – Large bodies of water located in front of, on top of, or beneath melting glaciers.
- Typically dammed by unstable ice or loose sediment.
- Glacial Lake Outburst Flood (GLOF) – Occurs when the natural barriers of glacial lakes break, releasing large amounts of water.
- Causes significant downstream flooding.
- Examples –
- Kedarnath Flash Flood (2013) – Triggered by a GLOF in the Chorabari Tal glacial lake.
- Chamoli Flood (2021) – GLOF in the Nanda Devi Glacier region.
Causes of GLOF:
- Melting of Glaciers – Rapid glacier melting due to rising global temperatures increases water levels in glacial lakes.
- Increased water volume puts pressure on unstable ice and rubble boundaries, leading to breaches.
- Avalanches and Earthquakes – Landslides or ice avalanches near glacial lakes displace large volumes of water.
- Displaced water breaches natural dams, causing GLOFs.
- Extreme Meteorological Conditions – Heavy rainfall, extreme storms, and sudden temperature changes can destabilize glacial lakes.
- Climate Change Impact – The Himalayan-Hindukush region is highly affected by climate change.
- Accelerated glacier melting forms more glacial lakes, increasing GLOF occurrences.
- Volcanic Activities – Volcanic activities near glacial regions can melt glaciers, increasing GLOF risks.
- Susceptibility of Moraine Embankments – Moraines (debris carried by glaciers) act as natural barriers but are prone to breaching.
- Anthropogenic Reasons – Infrastructure development like dams and roads in mountainous areas intensifies geological stresses.
- Chamoli GLOF (2021) linked to multiple hydro power projects.
Read more about: Glacial lakes in the Himalayas
Source: The Hindu
Previous Year Question
Consider the following pairs:
Glacier River
1. Bandarpunch Yamuna
2. Bara Shigri Chenab
3. Milam Mandakini
4. Siachen Nubra
5. Zemu Manas
Which of the pairs given above are correctly matched?
[UPSC Civil Service Exam – 2019 Prelims]
(a) 1, 2 and 4 only
(b) 1, 3 and 4 only
(c) 2 and 5 only
(d) 3 and 5 only
Answer: (a)
Explanation:
Pair 3 is not correctly matched: Milam has its source from Gori Ganga
Pair 5 is not correctly matched: The Zemu glacier is sourced from Teesta River