Landslides in India

Landslides occur when a significant quantity of bedrock slides rapidly. The causes of landslides are far less apparent than earthquakes, tsunamis, volcanic eruptions, and cyclones. However, the landslides’ influence on the ecological environment and the country’s economy is somewhat devastating.

• Some relatively isolated elements influence the landslides
• Collecting data and monitoring the probability of landslides is complex and extremely expensive
• India has been categorised into various zones depending on past experiences, regularity, and causal links with key parameters like geology, slope, geomorphic agents, vegetation cover, land use, and human activities.

Vulnerability Zones for Landslides

Extremely High Vulnerability Zone: These landslide vulnerability zones are particularly unsteady, such as reasonably young mountainous regions (like the Himalayas), the northeastern areas, areas that frequently experience ground-shaking caused by earthquakes, and areas with a high concentration of human activity, notably those associated with the development of roads, dams, and other infrastructure.

High Vulnerability Zone: This category comprises areas with nearly identical circumstances to those found in the extremely high vulnerability zone. The sole variation among these two is the regulating elements’ balance, intensity, and recurrence. Excluding the plains of Assam, all Himalayan regions and states from the northeastern areas are present in the high vulnerability zones.

Medium to Minimal Vulnerability Zone: Occasional landslides occur in areas with little precipitation, such as the Trans-Himalayan areas of Ladakh and Spiti (Himachal Pradesh), distorted yet steady relief and fewer rainfall regions in the Aravali, rain shadow regions in the Western and Eastern Ghats, and the Deccan plateau. Jharkhand, Chhattisgarh, Odisha, Maharashtra, Madhya Pradesh, Andhra Pradesh, Tamil Nadu, Karnataka, Goa, and Kerala have the highest landslides owing to mines and subsiding.

Consequences and Control of Landslides

• At the base of the slopes, landslides are triggered by the action of water induced by heavy rainfall or snowfall, excess groundwater, and other factors. The downward movement of soil and rocks on slopes is caused by fractures across thin layers, especially with high shear stresses associated with these landslides.
• Roadblocks in steep and mountainous areas obstruct normal communication, tourism, and the delivery of daily necessities.
• The expense of rebuilding roads and embankments is extremely high. Current projects are also delayed, resulting in significant cost and time overruns. Dams built in hills can break down and flood the plains.
• It negatively influences the environment and biodiversity, which takes a long time to recover from.
• Landslides can bypass river waterways, causing floods and loss of life and property. 
• Example: In India, a landslide in Uttarakhand killed 5,700 people in 2013. This is the fifth-highest number of landslide deaths in the world.  Flash floods and landslides in Ladakh  2010 are another example.

Mitigation

• When dealing with landslides, it is usually best to use area-specific precautions.
• Some helpful actions include sponsoring large-scale afforestation projects and building bunds to control water movement.
• There should be a limitation on infrastructural developments and associated projects like dams and roads. Moreover, agriculture and cultivation should be limited to valleys and regions with moderate elevations, and lastly, controlling the establishment of big towns in high landslide vulnerability zones.
• In the northeastern hill states, wherein Jhumming (Slash and Burn/Shifting Cultivation) is still practised, terrace agriculture must be promoted.

NDMA Guidelines on Landslides

• The country’s landslide storage inventory should be updated on a regular basis.
• Mapping of landslide hazard zones at the macro and meso dimensions, in collaboration with the Border Roads Organisation (BRO), state governments, and local populations.
• Pilot projects will be carried out around the country in various regions for extensive study, monitoring, and assessment of the stability status and associated risk.
• Establishing institutional structures to raise awareness and preparation among various stakeholders.

• Setting up early warning systems based on the cost-benefit ratio and risk assessment as a result of the slide.
• Professionals and organisations engaged in the subject of landslide management might benefit from training and capacity building. Existing landslide courts and guidelines will be amended, and new codes should be formed.
• To help and provide scientific guidance and interventions for managing the occurrence of landslides, an autonomous centre for research and study in landslide management will be established.

Conclusion :

Landslide is a major natural disaster that causes loss of life, property and infrastructure. Landslide is generally referred to as the sudden moment of rock mass and Debris due to gravitation. It can be natural as well as manmade. Loss of life, agriculture, forest, human property, communication lines etc., are significant ill effects. Landslides depend on geological, topographical and climatic factors. Regions with steep slopes, high precipitation, devoid of vegetation, etc, are more prone to landslides.