"Nepal-Tibet Flash Floods: Earthquake-Triggered Avalanche Devastates Bhote Koshi River System"
GLOF (Glacial Lake Outburst Flood)
sudden breach of a glacial lake's moraine or ice dam, releasing a catastrophic flood surge
Glacial collapse and debris flow
mass detachment of ice and rock that dams a river, then bursts, distinct from a conventional GLOF
The Hindu Kush Himalaya (HKH) region sits at the active collision boundary of the Indian Plate and the Eurasian Plate, making it one of the world's most geodynamically active mountain systems. The terrain is geologically young, with steep gradients, unconsolidated glacial and sedimentary deposits, and massive glaciers at elevations above 4,500 metres. These characteristics create conditions for cascading, compound natural hazards: earthquakes, ice-rock avalanches, landslide dams, and Glacial Lake Outburst Floods (GLOFs) can chain together within hours. Nepal, straddling the central Himalayas, is especially exposed — its rivers descend from above 8,000 metres to the Gangetic plains within a short horizontal distance.
The Bhote Koshi river originates on the Tibetan Plateau and flows through Nepal's Rasuwa and Sindhupalchok districts before joining the Sun Koshi and eventually the Narayani–Gandak river system, which drains into Bihar and Uttar Pradesh. This transboundary hydrology directly links Himalayan glacial zones to the Indian plains. The corridor is also economically critical: the Araniko Highway and the Gyirong Port, a key Nepal-China trade crossing, run along or near it, and several large hydropower projects are sited along the river. The Rashtriya Barh Ayog (National Flood Commission) has identified approximately 40 million hectares of land in India as flood-prone, with Bihar, Assam, and West Bengal among the highest-risk states.
India's domestic disaster management framework is anchored in the Disaster Management Act, 2005, which established the National Disaster Management Authority (NDMA) and the National Disaster Response Force (NDRF). A key evolution in this framework has been the shift from reactive relief to proactive preparedness. The Sendai Framework for Disaster Risk Reduction (2015–2030) identifies mountain river systems in high-seismicity zones as priority areas for early warning investment and transboundary cooperation — a principle directly relevant to the Nepal-Tibet event.
A GLOF occurs when a glacial lake, formed by meltwater dammed behind a moraine or ice barrier, breaches suddenly. The breach can be triggered by an earthquake, an ice or rock avalanche falling into the lake, or gradual weakening of the dam under hydrostatic pressure. The resulting flood wave is far more powerful than a normal river flood — it carries ice, rock, and sediment, travels at high speed, and can destroy infrastructure many kilometres downstream within minutes. The International Centre for Integrated Mountain Development (ICIMOD), based in Kathmandu, has documented accelerating GLOF risk across the HKH region as glaciers melt faster and moraine-dammed lakes grow larger and more stressed.
Historically, major Himalayan disasters have followed two distinct triggering mechanisms. The Kedarnath disaster of 2013 was initiated by a GLOF: a glacial lake overflowed and breached its moraine dam, releasing a catastrophic volume of water. …
Differentiate the causes of landslides in the Himalayan region and Western Ghats.
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?
Which of the following has/have shrunk immensely/dried up in the recent past due to human activities ?
1.Aral Sea
2.Black Sea
3.Lake Baikal
Select the correct answer using the code given below :
Consider the following statements regarding the Bhote Koshi river system:
1.The Lhende Khola is a tributary of the Bhote Koshi river.
2.The Bhote Koshi is a transboundary river flowing through Tibet and Nepal.
3.The Bhote Koshi eventually joins the Trishuli and then the Narayani river system.
4.The Narayani river drains into the Brahmaputra before entering the Bay of Bengal.
How many of the above statements are correct?
Consider the following pairs:
Geographic feature / Associated hazard mechanism
1.Glacial lake moraine dam failure — GLOF
2.Earthquake-triggered ice-rock avalanche forming a river blockage — Landslide Dam Outburst Flood
3.Rapid snowmelt combined with heavy rainfall — Flash flood in plains
4.Narrow high-altitude river gorge — Reduced flood velocity
How many of the above pairs are correctly matched?
With reference to Glacial Lake Outburst Floods (GLOFs) in the Himalayan region, consider the following statements:
1.GLOFs occur when a natural dam of ice or moraine holding a glacial lake fails suddenly.
2.Accelerating glacial melt due to climate change is increasing the frequency of GLOFs in the Hindu Kush Himalaya region.
3.GLOFs affect only the country in which the glacial lake is located and do not pose transboundary risks.
Which of the statements given above is/are correct?
Match the following rivers/ports with their correct descriptions:
List I / List II
A.Gyirong Port — 1. Major hydropower river in Nepal draining into the Ganga system
B.Narayani — 2. Key trade crossing on the Nepal-Tibet border
C.Lhende Khola — 3. High-altitude tributary of the Bhote Koshi river
D.Trishuli — 4. River joining the Narayani before entering the Gangetic plains
Select the correct answer using the code given below:
With reference to the Sendai Framework for Disaster Risk Reduction, consider the following statements:
1.It covers the period 2015 to 2030.
2.One of its four priorities is strengthening disaster risk governance to manage disaster risk.
3.It is legally binding on all UN member states.
4.It identifies multi-hazard early warning systems as a key instrument for reducing disaster losses.
Which of the statements given above are correct?
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