Landslide destroys houses in Himachal

Landslide destroys houses in Himachal

Subject: Geography

Context: Rescue operations are under way in the Boh valley in Kangra district after a landslip, in which one person died and nine are feared trapped beneath the debris.

Concept:

Landslides:

• A landslide is defined as the movement of a mass of rock, debris, or earth down a slope.
• They are a type of mass wasting, which denotes any downward movement of soil and rock under the direct influence of gravity.
• The term landslide encompasses five modes of slope movement: falls, topples, slides, spreads, and flows.

Causes:

• Slope movement occurs when forces acting downward (mainly due to gravity) exceed the strength of the earth materials that compose the slope.
• Landslides are caused due to three major factors: geology, morphology, and human activity.
• Geology refers to characteristics of the material. The earth or rock might be weak or fractured, or different layers may have different strengths and stiffness.
• Morphology refers to the structure of the land. For example, slopes that lose their vegetation to fire or drought are more vulnerable to landslides.
• Vegetation holds soil in place, and without the root systems of trees, bushes, and other plants, the land is more likely to slide away.
• Human activity which include agriculture and construction increase the risk of a landslide.

Region:

• Continent-wise, Asia suffers the maximum damages/losses due to landslides and within that, South-Asian nations are the worst sufferers including India which is one of the worst affected by landslides.

Mitigation:

• Restriction on the construction and other developmental activities such as roads and dams in the areas prone to landslides.
• Limiting agriculture to valleys and areas with moderate slopes.
• Control on the development of large settlements in the high vulnerability zones.
• Promoting large-scale afforestation programmes and construction of bunds to reduce the flow of water.
• Terrace farming should be encouraged in the northeastern hill states where Jhumming (Slash and Burn/Shifting Cultivation) is still prevalent.