A Glacial Break-In Uttarakhand :
A glacial break in the Tapovan-Reni area of Chamoli District of Uttarakhand led to a massive Flash Flood in Dhauli Ganga and Alaknanda Rivers, damaging houses and the nearby Rishiganga power project.
- It occurred in the river Rishi Ganga due to the falling of a portion of the Nanda Devi glacier in the river which exponentially increased the volume of water.
- Rishiganga meets Dhauli Ganga near Raini. So Dhauli Ganga also got flooded.
Flash Floods:
- These are sudden surges in water levels generally during or following an intense spell of rain.
- These are highly localized events of short duration with a very high peak and usually have less than six hours between the occurrence of the rainfall and peak flood.
- The flood situation worsens in the presence of choked drainage lines or encroachments obstructing the natural flow of water.
Causes:
- It may be caused by heavy rain associated with a severe thunderstorm, hurricane, tropical storm, or meltwater from ice or snow flowing over ice sheets or snowfields.
- Flash Floods can also occur due to Dam or Levee Breaks, and/or Mudslides (Debris Flow).
- In areas on or near volcanoes, flash floods have also occurred after eruptions, when glaciers have been melted by the intense heat.
- The intensity of the rainfall, the location and distribution of the rainfall, the land use and topography, vegetation types and growth/density, soil type, and soil water- content all determine just how quickly the Flash Flooding may occur, and influence where it may occur.
Glaciers
- Glaciers are a bulk of ice moving under its weight.
- It forms in areas where the amassing of snow goes beyond its ablation over many years.
- They are generally seen in the snow-fields.
- This largest freshwater basin covers around 10% of the land surface of the Earth.
- According to the topography and the location of the glacier, it can be categorized as Mountain Glacier (Alpine Glaciers) or Continental Glacier (Ice Sheets).
- The Continental Glacier moves outward in all directions whereas the Mountain Glacier moves from a higher to a lower altitude.
