Surge-type Glaciers | 08 May 2020

Why in News

Scientists from the Wadia Institute of Himalayan Geology (WIHG), Dehradun have found a seasonal advancement in 220 surging or surge-type glaciers in the Karakoram Range of Ladakh.

• WIHG is an autonomous institute under the Department of Science and Technology (DST).

Key Points

• Surging or Surge-type glaciers are a certain type of glaciers that have shown advancement in volume and length over a period of time.
  
  • Such glaciers go against the normal trend of considerable reduction in volume and length of most glaciers in the Himalaya in recent decades.
• Surging glaciers represent 40% of the total glaciated area of the Karakoram range.
• Surging glaciers do not flow at a constant speed, rather are subjected to cyclical flow instabilities.
• The oscillation of such glaciers have been broadly classified into two phases:
  
  • Active (Surge) Phase- brief (months to years) rapid flow.
  • Quiescent Phase- lengthy (tens to hundreds of years) slow flow or stagnation.
• It was inferred that surge during winter is more controlled because there is low amount of meltwater which flows unsteadily underneath the glaciers.
• The surging stops in summer because of the channelised flow of the melted water.

Significance of Studying Surging Glaciers

• Surging glaciers can lead to the destruction of villages, roads and bridges.
• They can also advance across a river valley and form an ice-dammed lake. These lakes can form catastrophic outburst floods.
• Therefore, monitoring of glacier surges, ice-dammed lake formation and drainage is of paramount importance.

Glaciers

• Masses of ice moving as sheets over the land (continental glacier or piedmont glacier if a vast sheet of ice is spread over the plains at the foot of mountains) or as linear flows down the slopes of mountains in broad trough-like valleys (mountain and valley glaciers) are called glaciers.
• The movement of glaciers is slow unlike water flow ranging from a few centimetres to a few meters per day. Glaciers move basically because of the force of gravity.
• Erosion by glaciers is tremendous because of friction caused by sheer weight of the ice.
  
  • The material plucked from the land by glaciers (usually large-sized angular blocks and fragments) get dragged along the floors or sides of the valleys and cause great damage through abrasion and plucking.
  • Glaciers can cause significant damage to even un-weathered rocks and can reduce high mountains into low hills and plains.
• As glaciers continue to move, debris gets removed, divides get lowered and eventually the slope is reduced to such an extent that glaciers stop moving, leaving only a mass of low hills and vast outwash plains along with other depositional features.