• A glacier break is suspected to have caused the flash floods in Uttarakhand’s Chamoli.
• When glaciers melt, the water in glacial lakes accumulates behind loose, natural “glacial/moraine dams” made of ice, sand, pebbles and ice residue.
• A GLOF refers to the flooding that occurs when the water dammed by a glacier or a moraine is released suddenly.
• Unlike earthen dams, the weak structure of the moraine dam leads to the abrupt failure of the dam on top of the glacial lake, which holds large volume of water.
• A failure of the dam has the potential of releasing millions of cubic metres of water in a short period, causing catastrophic flooding downstream.
• Glacial retreat due to climate change occurring in most parts of the Hindu Kush Himalaya has given rise to the formation of numerous new glacial lakes, which are the major cause of GLOFs.
• An “Inventory and Monitoring of Glacial Lakes / Water Bodies in the Himalayan Region of Indian River Basins” found that there are 352, 283 and 1,393 glacial lakes and water bodies in the Indus, Ganga and Brahmaputra basins respectively.
• NDMA has recommended use of Synthetic-Aperture Radar imagery to automatically detect changes in water bodies, including new lake formations, during the monsoon months.
Mains Paper 2: Geography
Prelims level: Glacial burst
Mains level: Reasons behind Glacial burst