Source: TOI
Context:
Heavy rainfall in Darjeeling and Kalimpong districts (West Bengal) triggered multiple landslides, killing at least 14 people and damaging key infrastructure, including the Dudhia Bridge and Teesta Bazaar link road. The incident highlights the increasing frequency of climate-induced disasters in the fragile Eastern Himalayan region.
About Landslides:
- A landslide is the downward movement of rock, soil, or debris along slopes under the influence of gravity.
- Triggered when shear stress exceeds the shear strength of slope materials.
Key Causes:
- Heavy rainfall, earthquakes, deforestation, unplanned construction, and road cutting.
- Human interference in fragile terrains accelerates slope instability.
Impacts:
- Destroys roads, bridges, and settlements, isolates communities, and disrupts vital supply and communication networks.
India’s Vulnerability to Landslides:
- Around 13% of India’s land area (0.42 million sq. km) is landslide-prone, per the Geological Survey of India (GSI).
- Major high-risk regions: Himalayas, Northeastern Hills, Western Ghats, Nilgiris, and Eastern Ghats.
- The Northeast alone accounts for 42% of the total hazard zone due to:
- Steep gradients, fragile geology, and intense monsoon rainfall.
- Unregulated construction and deforestation.
Darjeeling Landslides – Causes and Impact:
| Aspect | Details |
|---|---|
| Geographical Factors | • Located in the Eastern Himalayas, composed of young, unconsolidated rocks highly prone to erosion. • Intense monsoon rains cause waterlogging and weaken soil cohesion. • Unscientific infrastructure projects (road cutting, tunneling for hydropower, etc.) disturb natural drainage systems. • The region is seismically active, increasing the risk of slope failure and landslides. |
| Policy Implications | • The crisis calls for a pan-Himalayan sustainable development policy that integrates land-use planning, ecological zoning, and climate adaptation. • Focus on geo-hazard mapping, early warning systems, and green infrastructure for long-term resilience. |
NDMA Guidelines on Landslide Management:
| Component | Details |
|---|---|
| 1. National Landslide Risk Management Strategy (2019) | • Focuses on vulnerability mapping, hazard zonation, and early warning systems. • Utilizes IMD rainfall data and ISRO terrain imagery to forecast slope instability. • Aims to integrate disaster risk reduction (DRR) with regional development planning. |
| 2. Landslide Hazard Zonation (LHZ) Maps | • Prepared at a 1:50,000 scale by the Geological Survey of India (GSI). • Provides scientific input for urban planning, infrastructure siting, and land-use regulation. • High-resolution maps are being digitized for inclusion in state GIS portals. |
| 3. Mitigation Measures | • Slope stabilization using vegetative cover and bio-engineering methods. • Drainage improvement to prevent water accumulation and loss of soil cohesion. • Construction of retaining walls, gabion structures, and surface protection works. • Relocation of habitations and facilities from chronic slide-prone zones. |
| 4. Institutional Collaboration | • NDMA coordinates with GSI, NRSC (ISRO), DST, and CSIR institutions. • Development of real-time GIS-based monitoring systems and data-sharing platforms. • Emphasis on capacity building, community awareness, and state-level implementation frameworks. |
