What are landslides?
- Rapid sliding of a large mass of bedrocks is called landslides.
- Landslides are one type of Terrestrial natural disaster.
- Landslides are an exogenic sudden destructive force of landform development. It becomes a disaster if it harms human life and property.
- It is less destructive than other disasters such as earthquakes, cyclones, tsunamis, etc, but the consequences if far-reaching.
Cause of landslides:
Cause of landslides are both natural and anthropogenic:
Natural cause:
- Heavy rainfall or snowfall in mountainous regions cause landslides.
- Tectonic forces such as earthquakes also cause landslides.
- Steeper slopes led by gravitational force also cause landslides.
Human activities:
- Deforestation in hilly areas leads to the loosening of soil which causes a landslide.
- Unscientific land uses and construction activities in fragile areas
- Mining.
- Shifting cultivation.
Consequences of Landslides:
- The implication of landslides is relatively smaller areas but has far-reaching consequences such as blocking of roads, destruction of railways line, and channel blocking.
- Diversion of river course due to landslides can lead to floods and loss of life and property.
- Risking and costly travel experience due to landslides.
- Adverse effects on development activities.
Mitigation of landslides:
- Landslide is predictable and can be controlled and managed locally.
- Landslides can be predicted by analyzing the following:
- Past Experience.
- Frequency of landslides.
- Landform controlling factors like geology, geomorphic agents, slopes, land use, vegetation cover, and human activities.
- Need areas specific approach to deal with landslides problems
- Restriction on constructions and development activities [such as roads, dams, shifting cultivation] in steeper and moderate slopes areas.
- Promote a large afforestation program in hilly areas.
- Construction of bunds to reduce the flow of water.
- Terrace farming should be encouraged.
- Discouragement of shifting cultivation or Jhum cultivation in Hilly areas.
Landslide Vulnerability Zones:
The following are three landslides zones in India based on vulnerability:
- Very high Vulnerability Zones
- High Vulnerability zones
- Moderate to Low vulnerable zone
Very high Vulnerability Zones:
- Steeper and unstable region of the Himalayas, and Andaman & Nicobars.
- High rainfall with steeper slopes areas of western Ghats and Nilgiri, and the North-Eastern States.
- Areas with frequent ground shaking due to human activities and natural causes of the earthquake.
High Vulnerability zones:
- Northeastern states except Assam plains are high vulnerability zones of landslide.
Moderate to Low vulnerable zone:
The following regions experience low landslides.- Areas that receive less precipitation such as trans Himalayas Ladakh Spiti valley in Himachal Pradesh.
- Low Rainfall areas of Aravali.
- Rainshadow zones of Western Ghats and the Eastern Ghats.
- Landslides due to mining are common in the Chhotanagpur region, Madhya Pradesh, Maharashtra, Andhra Pradesh, and Karnataka, Goa, Kerala.
Landslides in the Himalayan region:
The Himalayan region is an unstable region and it is comprised of young fold mountains whose peaks are still rising.
The Himalayan region is also made up of mostly loose sedimentary rock which makes weak bases.
Cause of Landslides in the Himalayan region:
There are two major causes:
- Natural cause
- Human-made cause
The natural cause of Landslides in the Himalayan region:
- The whole Himalayas region is a tectonic active region and unstable as it is a region of the continental-continental convergence zone of the Indian Plate and the Eurasian plate. Himalayan peaks are still rising, hence it is prone to earthquakes and landslides disasters.
- The Indian plate is still moving in the northeastern direction and due to the same, stress is generated in the rocks.
- The slope of the southern side of the Himalayan ranges is steep as compared to the northern side. Heavy rainfall and snowfall on these steeper slopes cause landslides in the region.
- The Himalayan region is mostly made up of sedimentary rocks which make the region weak, as a result, it causes landslides.
Human-made cause:
The following are human-induced causes of landslides:
- Deforestation
- Jhum Cultivation
- Construction activities [ Road, highways, dam, etc]
- Industrial activities
- Mining activities
Mitigation measures of landslides in the Himalayan region:
- We can not control the natural cause of landslides but definitely, we can minimize the impact of landslides on humans by strengthening our knowledge about the pattern and timing of landslides.
- We can also prevent human-induced landslides through afforestation activities, slope management, and spreading awareness.
Try to solve the following questions:
- Landslide is a major problem in the Himalayan region. Discuss its causes and mitigation measures. ( 20 marks)( UPSC 2021 geography optional)
- Identify the Landslide-prone regions of India and suggest some measures to mitigate the disasters caused by these. (NCERT)
- Differentiate the causes of landslides in the Himalayan region and the Western Ghats.
- “The Himalayas are highly prone to landslides.” Discuss the causes and suggest suitable measures of mitigation.
- "Geomorphological changes are largely responsible for environmental hazards in the Himalayan region." Comment with relevant examples. (UPSC 2018, 200 words, 15 marks)
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