Why in news
- A sudden rise in water levels in the Trishuli river at Furke Khola in Nepal triggered high alerts in downstream districts of Bihar and Uttar Pradesh along the Gandak river.
What happened?
- Suspected Glacial Lake Outburst Flood (GLOF) or flash flood activity occurred near the Nepal-China border, sending sudden discharges into the Trishuli river system.
- Central Water Commission (CWC) monitored downstream flow into India, where Trishuli joins other tributaries to form the Gandak river system.
Hydrological link: Trishuli to Gandak
- Trishuli river originates in Tibet (China) as the Bhote Koshi/Trishuli and flows south into Nepal.
- It forms a major tributary of the Narayani river system in Nepal, which enters India at Valmiki Nagar (Bihar) as the Gandak river.
Why it matters
- Highlights transboundary disaster risks associated with retreat of Himalayan glaciers and expanding moraine-dammed lakes.
- Demonstrates the reliance of downstream Indian states (Bihar, UP) on real-time hydrometeorological data sharing with Nepal.
Key terms
Glacial Lake Outburst Flood (GLOF)
A sudden release of water from a lake fed by glacier melt that has been dammed by unstable ice or moraine.
Gandak River
A major left-bank tributary of the Ganga originating in the Himalayas of Nepal and entering India in north-western Bihar.
Prelims facts
- Trishuli river is a key tributary that merges into the Narayani basin in Nepal, forming the Gandak river upon entering India.
- GLOF disasters are triggered by moraine failure, heavy rainfall, or ice avalanches into glacial lakes.
Mains discussion
- Examine the necessity of transboundary flood management frameworks between India and Nepal in light of climate-induced Himalayan risks.
Source: PIB English
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