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Context

Severe rainfall-triggered landslides in Darjeeling and nearby areas have caused massive destruction, killing 24 people and isolating thousands by damaging vital infrastructure.

What are Landslides?

A landslide is the movement of a large mass of rock, earth, or debris down a slope under the influence of gravity. This movement can be rapid or gradual and is triggered by factors like heavy rainfall, earthquakes, volcanic eruptions, and erosion at the base of a slope. 

Landslides are a type of mass wasting and include various forms of downslope movement, including falls, slides, spreads, and flows. 

What are the Reasons Responsible for Landslides?

Natural Causes

Intense Rainfall: Heavy or prolonged rainfall soaks the soil, increasing its weight and reducing the friction that holds the slope together.

Earthquakes: Himalayas are a tectonically active region. Seismic tremors shake the ground, destabilizing slopes and triggering landslides.

Slope Gradient: Steeper slopes are naturally more vulnerable to the pull of gravity and, therefore, more likely to experience landslides.

Geological Weakness: Himalayan region is composed of young, fragile sedimentary rocks, making it naturally more prone to landslides than the older, more stable crystalline rocks of the Western Ghats.

River Erosion: Rivers can erode the base or "toe" of a slope, making it unstable and prone to collapse.

Human-Induced Causes (Anthropogenic Factors)

Deforestation: Roots of trees and vegetation act as natural binders for the soil. Removing this cover for agriculture or construction exposes the soil to erosion and increases instability.

Unscientific Construction: Construction of roads, buildings, and dams involves cutting into hillsides. This slope-cutting disrupts the natural angle and stability of the terrain, making it vulnerable to collapse.

Mining and Quarrying: These activities remove large amounts of rock and soil, weakening the geological structure of the area.

Changes in Land Use: Shifting from forests to agriculture or settlements on sloped land increases the load and alters water drainage patterns, raising the risk of landslides.

What are the Major Regions Vulnerable to Landslides in India?

According to the Geological Survey of India (GSI), about 12.6% of India's land area is prone to landslides. The major vulnerable regions are:

• Himalayas: Most affected region, including Jammu & Kashmir, Himachal Pradesh, Uttarakhand, Sikkim, and the Darjeeling region of West Bengal. The combination of steep slopes, fragile geology, and seismic activity makes this zone highly unstable.
• Northeastern Hill Ranges: Arunachal Pradesh, Nagaland, Mizoram, and Manipur experience frequent landslides, exacerbated by heavy rainfall.
• Western Ghats: Landslides in parts of Kerala, Tamil Nadu, Karnataka, and Maharashtra, primarily triggered by intense monsoon rains acting on steep slopes with thick soil cover.
• Eastern Ghats: Some parts of the Eastern Ghats in Andhra Pradesh and Odisha are also susceptible.

What are the Impacts of Landslides?

Loss of Life and Property:  The most direct impact is the loss of human life and the destruction of homes and property.

Infrastructure Damage: Landslides destroy critical infrastructure like roads, bridges, railway lines, and communication networks, leading to the isolation of communities and hampering relief efforts.

Economic Disruption: Damage to infrastructure, agriculture (burial of fertile land), and the disruption of tourism lead to economic losses for the affected regions.

Environmental Damage:  Landslides cause soil erosion, loss of forest cover, and block rivers, forming "landslide dams." These dams pose a threat of catastrophic downstream flooding if they suddenly breach.

Disaster Management Framework in India

India has a robust, multi-tiered disaster management framework, established under the Disaster Management Act, 2005.

National Disaster Management Authority (NDMA): This is the apex body, chaired by the Prime Minister, responsible for laying down policies, plans, and guidelines for disaster management.

State Disaster Management Authority (SDMA): Headed by the respective Chief Ministers, the SDMA is responsible for implementing the national plan at the state level.

District Disaster Management Authority (DDMA): Chaired by the District Collector, the DDMA acts as the planning and coordinating body for disaster management at the district level.

National Disaster Response Force (NDRF): This is a specialized force trained for responding to natural and man-made disasters, including search and rescue operations in landslide-affected areas.

For landslides: The Geological Survey of India (GSI) is the nodal agency responsible for research, monitoring, and developing early warning systems.

• The National Landslide Risk Management Strategy (2019) focuses on creating a "landslide-resilient India" through hazard zonation, monitoring, early warning systems, and capacity building.

Mitigation and Adaptation Strategies

Hazard Zonation and Land-Use Planning

• Creating detailed landslide hazard maps, like the Landslide Atlas of India by ISRO, to identify and classify vulnerable zones.
• Based on the maps, governments must enforce strict regulations that prohibit or restrict construction and other high-risk activities in the most vulnerable areas.

Structural Measures  

• Construction of retaining walls and gabion walls to support vulnerable slopes.
• Slope reinforcement using techniques like soil nailing and rock bolting.
• Improving drainage systems to safely channel rainwater away from unstable slopes.

Non-Structural Measures 

• Large-scale afforestation and eco-restoration to stabilize slopes naturally.
• Strict regulation and enforcement of land-use policies to prevent construction in high-risk zones.
• Developing and implementing Landslide Early Warning Systems (LEWS).

Way Forward

Strengthening Governance: Ensure strict enforcement of land-use and environmental regulations without political interference.

Investing in Science and Technology: Scale up the use of technology for accurate landslide forecasting and real-time early warning systems.

Integrate Science into Policy: Landslide hazard maps and scientific assessments must be made a mandatory part of all development and urban planning processes in hilly regions.

Empowering Local Communities:  Local communities are the first responders in any disaster. Investing in community-based disaster preparedness through training programs like 'Aapda Mitra' can save countless lives.

Conclusion

Landslides are natural, but their growing destruction originates from human neglect. Unregulated mountain development worsens risks. Adopting scientific planning, strict regulation, and community-driven resilience—guided by global best practices—can help India protect its fragile ecosystems and ensure safer, sustainable mountain livelihoods.

Source: INDIAN EXPRESS