1. Classification of Himalayas
  2. Hazards in the Himalayan Eco-System
    1. Regions and disasters
    2. Landslides: Reasons
    3. Landslides: Damage
    4. Suggestions to fix problem
  3. E1: Avalanche Mitigation

Classification of Himalayas

Three main geological divisions of India.

  1. Himalayas, also known as the Extra-Peninsula
  2. Indo-Gangetic Plains
  3. Peninsula

Further, Himalayas classified via two methods:
Method #1

  • Himalayas are classified, from west to east, into four regions:
  1. Punjab Himalaya – area between Indus and Sutlej rivers.
  2. Kumaon Himalaya – area between Sutlej and Kali rivers
  3. Nepal Himalaya- area between Kali and Tista rivers.
  4. Assam Himalaya- area between Tista and Brahamputra rivers.


Map India Landslide Earthquake prone areas

  • three regions: the Western, Central and Eastern Himalaya
  • Nepal Himalaya constitutes the Central Himalaya and the mountainous area to its west and east are known as Western and Eastern Himalaya respectively

Hazards in the Himalayan Eco-System

  • All major types of disasters, prominently
  1. earthquakes,
  2. landslides,
  3. avalanches,
  4. flash floods
  5. forest fires
  6. soil erosion
Regions and disasters
Altitude Type of disaster
Over 3500m snow avalanches and glacial lake outburst floods (GLOFs)
500 to 3500 m flash floods; landslides and mudflows

Landslides: Reasons

  1. indiscriminate chopping down of trees.
  2. slash and burn cultivation technique called ‘JHUM,’
  3. Road construction and mining.
  4. Every increasing population, grazing, urbanization etc. has destroyed the dense natural evergreen forest cover.

Such activities have disrupted the ecological balance, thereby resulting in loosening of the soil. During the heavy rain, this leads to soil erosion and frequent landslides

Landslides: Damage

  • Every year, landslides in the region kill dozens of people and cause widespread damage to several villages such that they have now become almost unfit for habitation.
  • They create blockades in the road network and river system, which in turn, cause floods.
  • The terraced farm fields have been destroyed that cannot be easily renovated or made productive again.
  • The road network remains closed for long periods causing indescribable hardship to the villagers who get their basic supplies and provisions from the neighbouring areas.
  • Water sources are disrupted and chocked by debris from landslides.
  • The river sediment load is increased considerably, causing irregular courses and frequent breaching of the banks- resulting into unexpected floods.
  • The water channels are affected from the up hillside due to which the villagers are devoid of water for irrigation purposes. This adversely affects agriculture production in the region.

Suggestions to fix problem

  1. Store Excess water in catchments areas to reduce the fury of flash floods, recharge the ground water and improve the environment.
  2. Dig runoff collection ponds in the catchments.
  3. Grow fuel / fodder trees in all of the common lands.
  4. Plantation in barren areas, especially on slopes, with grass cover is an important component of integrated watershed management programme.
  5. Grazing should be completely restricted. After the area is completely protected from grazing, better grasses can be planted.
  6. The grasses of industrial importance should also be planted so that there is some economic return to the farmers as well.
  7. Use the surface vegetative cover to protect the land from raindrop’s beating action, bind the soil particles and decrease the velocity of flowing water.

Reference: IGNOU MPA 018/Chapter 3.

Avalanche Mitigation

Topic in news because in April 2014, ~dozen Nepali Sherpa died during an avalanche in Mt. Everest base camp. This lead to protests and other sherpas refusing to guide the tourists.

Q. List the factors responsible for avalanches and suggest disaster mitigation measures. (200 words)

Rapid downslope movement of snow, rocks and debris- is called Avalanche.

Large avalanches have speed of upto 200kmph, resulting in massive destruction of forests, highways, houses and power lines.


Whenever gravitational force exceed the mechanical strength of snow cover- avalanche occurs. This happens by “triggers”- natural and artificial

Natural triggers Artificial triggers
  • Large mass of fresh snowfall
  • blizzards
  • Global Warming, Rain
  • earthquakes
  • Skiing and mountaineering
  • Deforestation
  • loud sounds
  • Shouts
  • machine noise
  • sonic booms

Mitigation in Avalanche prone Areas

  1. Don’t construct buildings for winter occupancy
  2. Avoid construction of power lines, highways and railroads. It they must be constructed then design for minimum impact.
  3. It is possible to forecast avalanche, by studying Snow deposition data, heat input, slope angle.
  4. Use Remote sensing technology & satellite imagery to obtain such data.
  5. Only allow agriculture and recreational activities during summer and spring.
  6. Use explosives to create smaller, controlled avalanches and thus avoid building up of snow for large unpredictable destructive avalanches.
  1. Quick response teams (QRT) from local administration and NDRF, with standard Avalanche equipment and devices like GPS, Radio Beacons, shovels and sniffer dogs.

~180 words.

Already done:

  1. Snow and Avalanche Study Establishment (SASE) : forecasts snow avalanches
  2. Border road organization (BRO): keeps the highway paths clear after avalanches- particularly the Rohtang Pass and Baralachla Pass.


  1. Most Avalanche victims die of suffocation (lack of oxygen) and not hypothermia (extreme cold temperature)
  2. After 35 minutes, the survival chance is 30%
  3. After two hours, survival change is ~0%
  4. Therefore self-rescue or companion rescue is vital, because NDRF / sarkaari help will take hours to reach.

Mock MCQ: Which of the following can cause avalanches?

  1. Shouting
  2. sonic booms
  3. Earthquakes

Answer choice

  1. Only 3
  2. Only 1 and 3
  3. Only 2 and 3
  4. All of them