Context:
A study reveals that climate change has increased the frequency of floods in High Mountain Asia (HMA) since 2000.
Key Observations:
- Study analyzed flood events in HMA from 1950 to 2023 and confirms that temperature rise is the key driver of increased flooding.
- Since 1950, HMA has been warming at 0.3°C per decade.
- Rising unpredictability in flood timing, with most events occurring during monsoon, but there’s an increase in floods outside these times.
- Planetary heating from burning oil, coal, and gas drives the rise in all four types of floods in the Asian region.
About High Mountain Asia (HMA)
- Also called the ‘Asian Water Tower’.
- Important source of freshwater as it holds the largest reservoir of frozen water outside polar regions.
- Feeds 10 major rivers and supports more than 2 billion people.
- Consists of the Tibetan Plateau surrounded by mountain ranges:
- Tien Shan, Pamir, Hindu Kush, and Karakoram in the west
- Himalayas in the south and southeast
- Qilian Shan in the east
- Mountains cover 22% of Earth’s land surface but hold 50% of the world’s global biodiversity hotspots.
4 Types of Floods in High Mountain Asia (HMA)
- Rain/Pluvial Floods (PF): Triggered by extreme rainfall, leading to surface runoff and flash floods. Common in Himalayas.
- Snowmelt-induced Floods (SF): Rising temperatures accelerate snowmelt, increasing river discharge. Most frequent in Tien Shan.
- Glacial Lake Outburst Floods (GLOFs): Caused by glacial lakes breaching due to melting glaciers or landslides. Common in Karakoram and Himalayas.
- Landslide-Dammed Lake Outburst Floods (LLOFs): Occur when landslides block rivers, forming temporary lakes that later breach. Mostly in Hengduan Mountains.
Read more about: Glacial lakes in the Himalayas
Source: TOI
Previous Year Question (Click here to Solve Topic-wise PYQs)
Consider the following pairs:
Peak: Mountains
1. Namcha Barwa — Garhwal Himalaya
2. Nanda Devi — Kumaon Himalaya
3. Nokrek — Sikkim Himalaya
Which of the pairs given above is/are correctly matched?
[UPSC Civil Services Exam – 2022 Prelims]
(a) 1 and 2
(b) 2 only
(c) 1 and 3
(d) 3 only
Answer: (b)
Explanation:
Pair 1 is not correctly Matched: Namcha Barwa, situated in a remote area of southeastern Tibet, is not frequently visited by outsiders, while the Garhwal Himalayas are located in the Indian state of Uttarakhand. Namcha Barwa stands within the Great Bend of the Yarlung Tsangpo River, which enters an impressive gorge through the Himalayas and emerges as the Siang before eventually becoming the Brahmaputra.
Pair 3 is not correctly Matched: Situated on the Tura Range, which is part of the Meghalaya Plateau in northeast India, the Nokrek Biosphere Reserve boasts an average altitude of 600 meters.