Landslides have become frequent hazards in the Himalayan regions. Examine the causes of these landslides and measures needed to mitigate them. (200 Words)
The sudden movement of rock, debris or earth along the slope is called landslide.
The various causes of landslides are:
- Natural causes-
- Landslides are generally associated with natural calamities like earthquake, volcanic eruptions, floods, cloudburst, etc.
- Long spell of rainfall
- Loose soil cover and sloping terrain
- Anthropogenic causes-
- Rapid urbanization and changes in land use patterns
- Rampant deforestation and mining activities like blasting and quarrying, etc.
- Increased industrialisation leading to climate change and weather disturbances
- Change in river flow due to construction of dams, barriers, etc.
Various measures needed to mitigate them are-
– Hazard mapping by demarcating areas prone to landslides and avoiding stress on those areas for settlement
– Construction of retention walls to avoid land from slipping
– Increasing afforestation and vegetation cover
– Practise measures to check soil erosion like terrace farming, contour ploughing, etc.
– Implementing surface drainage control works to control the movement of landslide along with rain water and spring flows.
– Proper planning of developmental processes following sustainable methods.
Differentiate between soil creep, soil flow and landslides. Which of these is/are commonly found in India? Why and where? Examine. (200 Words)
The different combinations of soil, water, topography and gravity results into either soil creep or soil flow or landslides.
Land creep: Slow and gradual movement of soil over gentle slopes. It can happen even in the absence of water due to wind/ animal peddling. Minimal water can act as lubricant in this process.
Land flow: It a bit faster than land creep. It happens when water content is adequate enough to form a suspension with underlying soil. It is visibly seen over weeks and months. Even it can be observed over days/ hours immediately after the rains.
Landslides: It is a sudden fall of land mass due to acute slopes. And lubricant action of water. This is due to detachment of land mass over regolith where the water detaches the weak junctions.
In India all the three forms are evident. Soil creep and soil flow are common causes of soil erosion in India. They happen all across India, throughout the year. But as India gets nearly 75% of its rain during monsoons and western disturbances landslides are also not uncommon. Recent Uttarakhand floods and Pune landslides are examples for that.