- A landslide can be defined as the movement of a mass of rock, debris, or earth down a slope.
- Landslides are a type of mass wasting, which denotes a downward movement of soil and rock under the direct influence of gravity.
- Landslides results in a loss of about of Rs. 100 crore to Rs. 150 crore per annum in whole of India.
Causes of Landslides
- This refers to characteristics of the material.
- Such as whether the earth or rock is weak or fractured, or different strengths and stiffness of different layers of the soil.
Heavy Rainfall and Earthquakes
- The vulnerability of above 40% of the Kumaon Himalayan region to landslides is caused by earthquakes.
- Additionally, heavy rainfall often may result in landslides.
- Morphology refers to the physical structure of the land.
- From experience we know that slopes that lose their vegetation to fire or drought are more vulnerable to landslides.
- This is because 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 activities such as mining or quarrying will result in the loss of vegetation cover and soil gravel.
- This also lowers the groundwater retention capacity which increases the risk of flooding.
- Shifting cultivation is especially common in himalayan regions and Northeast areas.
- Every year, residents burn the forests for cultivation purposes which deteriorates the quality of topsoil, causing erosion during heavy rainfall.
- This results in increased vulnerability to landslides in these regions.
- Population pressure in urban areas of India is rising at an alarming rate.
- This results in intensive urbanisation activities such as establishing commercial housing projects and road construction which reduce the vegetation cover.
- This results in an increasing frequency of landslides in such regions.