Syllabus: Disaster Management
Source: IE
Context: Heavy rainfall triggered multiple landslides in Darjeeling and Kalimpong, killing at least 14 people and destroying vital infrastructure including the Dudhia bridge and Teesta Bazaar link road.
About Landslides:
What it is?
- A landslide is the downward movement of rock, debris, or soil along a slope under gravity.
- It occurs when the shear stress exceeds the shear strength of slope materials, often due to heavy rainfall, earthquakes, deforestation, or human activity.
- These events disrupt slope stability and can destroy roads, settlements, and infrastructure, especially in hilly terrains.
India’s Vulnerability:
- Nearly 13% of India’s land area (0.42 million sq. km) is landslide-prone, as per the Geological Survey of India (GSI).
- High-risk zones include the Himalayas, Northeastern hills, Western Ghats, Nilgiris, and Eastern Ghats.
- The Northeast alone accounts for 42% of the total hazard zone due to fragile geology, steep gradients, heavy monsoons, and unregulated construction.
- India’s tectonic activity and population pressure amplify the frequency and intensity of slope failures.
About Darjeeling Landslide:
- Geographical Reasons:
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- Darjeeling, in the Eastern Himalayas, sits on young, unconsolidated rock strata prone to erosion and slope failure.
- The region receives intense monsoon rainfall, causing water saturation and loss of soil cohesion.
- Unscientific construction, deforestation, road cutting, and hydropower tunneling have degraded natural drainage and slope stability.
- The district’s seismic vulnerability adds to the cumulative risk of recurrent landslides.
- Historical Record:
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- Darjeeling has a century-long record of catastrophic landslides — major events occurred in 1899, 1934, 1950, 1968, 1975, 1980, 1991, 2011, and 2015.
- The 1968 floods were among the worst, killing over 1,000 people and reshaping the region’s terrain.
- The 2023 Sikkim GLOF disaster caused ₹25,000 crore in damage, illustrating how hydro-climatic hazards are now linked across Himalayan states.
- These recurring events show a pattern of high exposure and weak mitigation in the region.
Current Concern:
- Rapid urbanization and expansion of roads, hotels, and hydropower projects have far exceeded the area’s carrying capacity.
- Encroachments along rivers and jhoras (mountain streams) have blocked natural drainage, increasing waterlogging and slope pressure.
- Frequent slope collapses now threaten key infrastructure like bridges, highways, and rail lines that connect the Siliguri Corridor (“Chicken’s Neck”), a strategic link to the Northeast and Bhutan.
- Hence, Darjeeling’s ecological fragility has evolved into a national security concern, demanding integrated Himalayan policy and sustainable planning.
NDMA Guidelines on Landslides:
- National Landslide Risk Management Strategy (2019): Focuses on vulnerability mapping, hazard zonation, and early warning systems using IMD rainfall forecasts and ISRO terrain data.
- Zonation Maps: Landslide Hazard Zonation (LHZ) maps at 1:50,000 scale identify risk-prone zones for planning and regulation.
- Mitigation Measures: Recommend slope stabilization through vegetation, bio-engineering, drainage improvement, retaining walls, and relocation from chronic slide zones.
- Institutional Coordination: NDMA collaborates with GSI, NRSC, DST, and CSIR to develop real-time data-sharing and GIS-based monitoring.
Way Ahead:
- Scientific planning: Enforce hill zone building codes and prohibit construction in high-risk slopes and drainage corridors.
- Early warning expansion: Extend rainfall-linked landslide forecasting systems (trialed in Kerala, Sikkim, Uttarakhand) across all Himalayan states.
- Eco-restoration: Promote afforestation, jhora rejuvenation, and slope bio-engineering to stabilize fragile hills.
- Institutional reform: Establish a Himalayan Disaster Research and Management Centre in Darjeeling for coordinated response and capacity building.
- Strategic integration: Treat the Darjeeling–Sikkim belt as a national security-sensitive eco-zone under the Act East Policy framework.
Conclusion:
The Darjeeling disaster is a reminder that the Himalayas are ecologically fragile yet geopolitically crucial. Sustainable planning, scientific monitoring, and community-based preparedness must replace ad-hoc development. India’s mountain policy must blend ecological prudence with strategic foresight to safeguard both lives and national interests.
