Fresh Glacial Lakes Form At Source Of Nepal’s Avalanche, Pg11

Key Highlights:

• Two new glacial lakes have formed in Nepal, near the source of an ice-rock avalanche that caused flooding in the Bhote Koshi-Trishuli river system.
• The lakes measure approximately 19.80 hectares and 7.28 hectares respectively, with their water volume currently unknown.
• The formation was independently confirmed by Suhora Technologies using high-resolution satellite imagery, identifying one lake spanning 20.25 hectares in the Lhende Khola region near the Nepal-Tibet border.
• India's National Disaster Management Authority (NDMA) acknowledges limitations in early warning systems, stating that while warnings can be given 30-45 minutes in advance, the sheer volume of water in such events leaves "no escape".

New Glacial Lakes.jpg

Detailed Insights:

• The Bhote Koshi-Trishuli river system is a transboundary, snow-fed Himalayan river system crucial for Nepal and eventually flowing into India as part of the Gandak River and then the Ganga basin.
• The recent flooding was triggered by an ice-rock avalanche on August 26, which likely created a temporary dam, leading to water accumulation and subsequent flash floods.
• The newly formed lakes are dammed by moraines, which are unstable piles of glacial debris, increasing the risk of a Glacial Lake Outburst Flood (GLOF).
• Satellite monitoring is a key tool for tracking the extent and stability of these lakes, but ground-based investigation is essential for assessing their origin, depth, and potential downstream risks.
• The incident highlights the vulnerability of Himalayan regions to climate-induced disasters, with rising temperatures accelerating glacier retreat and glacial lake expansion.
• India has a National GLOF Risk Mitigation Programme with an allocated ₹150 crore for four Himalayan states, focusing on assessment, monitoring, and mitigation strategies for high-risk glacial lakes.

Scientific/Technical Concepts Involved:

• Glacial Lake: A body of water formed when a glacier erodes land, and the resulting depression fills with meltwater.
• Moraine: An accumulation of unconsolidated glacial debris (rock, gravel, sand) deposited by a glacier, often forming natural dams for glacial lakes.
• Ice-rock avalanche: A rapid downslope movement of rock and ice, often triggered by the collapse of a rock mass near a glacier, which can transform into destructive debris flows.
• Glacial Lake Outburst Flood (GLOF): A sudden release of a large volume of water from a glacial lake due to the failure of its natural dam, causing devastating floods downstream.