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Showing posts from January, 2021

The Five FAQs - Avalanche

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What is an avalanche?  An avalanche is an event that occurs when a cohesive slab of snow lying upon a weaker layer of snow fractures and slides rapidly down an inclined slope such as a mountainside. Why does it occur?  An avalanche occurs when a layer of snow collapses and slides downhill. Avalanches are caused by a steep slope, snow cover, a weak layer in the snow cover and are triggered by either natural forces, such as precipitation, wind drifting snow, rapid temperature changes or human activity. What are the signs of an avalanche?  Avalanches mostly occur on steep slopes - between 25 and 45 degrees, conv ex slopes (spoon-shaped). Loose, underlying snow is more dangerous than when compact and new snow is particularly dangerous. Rapid snow settlement is a good sign as loose, dry snow slides more easily. Low temperatures increase the duration of snow instability, while a sudden temperature increase can cause wet snow slides. How to stay prepared?  Keep track of weather before heading

Reducing the risk of Lake Outburst Floods

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Glacial retreat due to global warming occurring in most parts of the Hindu Kush Himalaya, has given rise to the formation of numerous new glacial / landslide lakes which bear the potential for disastrous Glacial Lake Outburst Floods (GLOFs) or Landslide Lake Outburst Floods (LLOFs). A Glacial Lake Outburst Flood (GLOF) is a type of flood occurring when water dammed by a glacier or a moraine is released. When glaciers melt, the water in these glacial lakes accumulate behind loose, naturally formed ‘glacial/moraine dams’ made of ice, sand, pebbles and ice residue. A catastrophic failure of the dam can release the water over periods of minutes to days causing extreme downstream flooding. Peak flows as high as 15,000 cubic meters per second have been recorded in such events. GLOF / LLOF events have killed thousands in many parts of the world and some of the largest events have occurred in the Himalayas, such as, the 2013 Chorabari lake outburst known as Kedarnath disaster in Uttarakhand, s