Danger from above, Pg8

Key Highlights:

• A flash flood ravaged Nepal's Himalayas and foothills on Wednesday, resulting in at least 359 deaths and 300 Indians missing.
• Satellite imagery, including from the Indian Space Research Organisation, indicates a glacier collapse or ice-rock avalanche in Tibet as the likely cause.
• Extensive damage was reported along the Bhote Koshi and Trishuli corridors, impacting settlements, hydropower, and infrastructure.
• Warnings of potential secondary flooding from upstream debris blockages persist, even after the immediate flood wave passed.

Detailed Insights:

• The initial suspicion of an earthquake as the cause was not supported by evidence.
• This event draws parallels with the October 2023 South Lhonak Lake disaster in Sikkim, which was a Glacial Lake Outburst Flood (GLOF).
• The Indian Himalayas host approximately 7,500 glacial lakes and 15,000 glaciers, some monitored through remote sensing.
• Accurately forecasting glacier collapses is challenging due to the remote and inhospitable nature of these high-altitude lakes.
• Hydropower projects and human settlements in vulnerable zones are increasingly susceptible to such natural outbursts, exacerbated by global warming.
• Governments must enforce strict construction codes, discourage large projects in vulnerable areas, and invest in robust glacier health tracking for disaster planning.

Scientific/Technical Concepts Involved:

• Glacial Lake Outburst Flood (GLOF): A sudden release of water from a glacial lake due to the failure of its natural dam, often caused by ice or moraine collapse.
• Western Disturbance: An extratropical storm originating in the Mediterranean region, bringing winter precipitation to the Indian subcontinent's northwestern parts.
• Remote Sensing: The process of gathering information about an object or area from a distance, typically using satellites or aircraft.