Glacial Lake Outburst Flood in Sikkim

• A Glacial Lake Outburst Flood (GLOF) occurred in the South Lhonak Lake in Sikkim,killing many and causing the rise of water levels in Teesta river.

ABOUT GLOF

• Retreating glaciers, like several in the Himalayas, usually result in the formation of lakes at their tips, called proglacial lakes, often bound only by sediments and boulders or moraines.
• A GLOF is a type of flood occurring when water dammed by a glacier or a moraine is released suddenly.
  • Moraine is a mass of rocks and sediment carried down and deposited by a glacier, typically as ridges at its edges.
  • Unlike earthen dams, the weak structure of the moraine dam leads to the abrupt failure of the moraine dam bounding the glacial lake.

REASONS BEHIND GLOFS

• Glacial retreat increases meltwater.
• Cascading flood from upstream lakes.
• Geological Triggers as earthquakes can destabilize moraines.
• Landslides and ice avalanches.
• mass tourism, infrastructure boom etc.