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
Geology
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
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.
Mining
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
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.
Urbanisation
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.