"Gyirong Border Crossing Destroyed as Himalayan Glacier Collapse Kills Hundreds"
Glacial Lake Outburst Flood (GLOF)
sudden, catastrophic release of water when a glacial lake's ice or moraine dam fails, producing high-velocity debris-laden floods.
Moraine dam
ridge of loose rock debris deposited by a retreating glacier that can impound meltwater to form a glacial lake.
The Himalayan arc is among the most geologically active and disaster-prone regions on Earth. The mountains are geologically young fold mountains, still rising due to the ongoing collision of the Indian and Eurasian tectonic plates. This tectonic youth means rocks are fractured, poorly consolidated, and highly susceptible to erosion. The region holds the largest concentration of glaciers outside the polar regions, earning it the name the Third Pole. As global temperatures rise at roughly twice the global average rate in the Himalayas, glaciers retreat and meltwater collects behind natural dams of ice or loose rock debris called moraines, forming glacial lakes. When these dams fail suddenly, the result is a Glacial Lake Outburst Flood (GLOF): a violent surge of water, boulders, and debris that can devastate narrow mountain valleys within minutes.
Nepal sits at the heart of this hazard zone. Its river systems, including the Trishuli, Koshi, Gandaki, and Karnali, originate in the high Himalayas and carry enormous sediment loads. The Bhotekoshi river in Rasuwa district is one of the most GLOF-prone corridors in the Hindu Kush Himalaya. It drains the glaciated Langtang region and eventually joins the Trishuli, flowing into the Narayani system, which crosses into India as the Gandak river. This shared hydrology means downstream impacts are a bilateral concern for both Nepal and India. India's own Himalayan states face identical risks, as demonstrated by the Sikkim GLOF of October 2023, which breached South Lhonak Lake and devastated the Teesta valley, and the 2013 Uttarakhand glacial burst, which killed around 6,000 people near the Kedarnath temple.
A key distinction relevant to disaster preparedness is the difference between landslide and flood triggers in the Himalayan region versus the Western Ghats. In the Himalayas, primary drivers are young tectonically active geology, steep gradients, seismic activity, glacial processes, and human interventions such as road cutting and hydropower construction. In the Western Ghats, landslides are driven mainly by intense seasonal rainfall on laterite soils, deforestation, and construction on relatively stable, older rock formations. Himalayan events tend to be sudden and high-velocity, triggered by geophysical processes, while Western Ghats events are more closely tied to rainfall intensity and land-use change.
A GLOF event typically begins with a trigger: an ice avalanche, an earthquake, a landslide falling into a glacial lake, or rapid snowmelt that destabilises a moraine dam. The dam fails, and the impounded lake drains catastrophically. Water volumes that took years to accumulate can discharge within hours, carrying boulders, trees, and heavy sediment loads at destructive speeds through narrow gorges. This makes GLOFs fundamentally different from ordinary monsoon-driven riverine floods, which rise gradually and allow some warning time. GLOFs can also trigger secondary hazards: landslides block river channels, forming temporary lakes that may themselves burst, compounding destruction downstream.
The geopolitical dimension of Himalayan flood risk is significant. The Tibetan Plateau, controlled by China, is the origin of major river systems including the Yarlung Tsangpo (Brahmaputra), the Indus, and upper Ganges tributaries such as the Bhote Koshi. China is therefore the dominant upper-riparian state, with India and Nepal as lower-riparian nations dependent on timely hydrological data from upstream. India and China historically managed this through bilateral Memoranda of Understanding (MoUs) on hydrological data sharing, covering the Brahmaputra and Sutlej basins. …
Account for the huge flooding of million cities in India including the smart ones like Hyderabad and Pune. Suggest lasting remedial measures.
Consider the following statements about river bridges connecting India with neighbouring countries:
1.'Maitri Setu', built over Feni river, connects Ramgarh in India with Sabroom in Bangladesh.
2.Jhulaghat suspension bridge connects India with Myanmar.
3.Mechi bridge and its approaches connect Panitanki Bypass in India with Kakarvitta in Nepal.
Which of the statements given above is/are correct?
Match the following rivers with their origin on the Tibetan Plateau and their downstream country of primary concern:
River — Downstream country primarily affected
1.Yarlung Tsangpo (Brahmaputra) — P. India (Northeast)
2.Indus — Q. Pakistan
3.Bhote Koshi — R. Nepal
Select the correct match:
Consider the following statements about the Gyirong border crossing between Nepal and Tibet:
1.It became the main land port between Nepal and Tibet after a 2015 earthquake damaged an alternative eastern route.
2.It serves as a transit point for Hindu pilgrims travelling to Mount Kailash in Tibet.
3.It is located on a wide river plain, making it relatively safe from glacial flood events.
Which of the statements given above is/are correct?
With reference to Glacial Lake Outburst Floods (GLOFs) in the Himalayas, consider the following statements:
1.A GLOF occurs when a dam formed by ice or moraine suddenly breaches, releasing large volumes of water.
2.Rising Himalayan temperatures are increasing the frequency and size of glacial lakes, raising GLOF risk.
3.The Sendai Framework for Disaster Risk Reduction calls for enhanced international cooperation on early-warning systems for transboundary hazards.
Which of the statements given above is/are correct?
Consider the following statements about glacial lakes on the Tibetan Plateau:
1.China has identified more than 3,000 glacial lakes on the Tibetan Plateau.
2.Of these, 187 are classified as high-risk and are monitored via remote sensors or ground teams.
3.All high-risk glacial lakes are located on the Chinese side of the India-China border.
Which of the statements given above is/are correct?
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