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Context
Landslides involve the sudden movement of rock, earth, or debris down a slope due to gravity. In July 2024, severe landslides in Kerala’s Wayanad district resulted in significant loss of life, property damage, and displacement.
Types of Landslides
Based on Materials Involved
- Rock Slide: Movement of bedrock down a slope, often involving detached rock masses.
- Debris Slide: Rapid downslope movement of loose, unconsolidated materials like soil, rock fragments, and organic matter.
- Soil Slide: Movement of saturated, loose soil, often mixed with vegetation.
- Loose Mudslide: Flow of loosely bound mud moving downslope.
Based on Material Movement
- Fall: Sudden free fall of rock or debris from a steep slope.
- Topple: Rotation of rock or soil blocks over a pivot point, causing them to fall forward.
- Slide: Downslope movement of a coherent mass along a defined slip surface.
- Rotational Slide: Curved sliding motion of material along a concave slip surface, often involving rotation.
- Translational Slide: Movement of material along a planar or nearly planar slip surface.
Based on Flow of Material
- Debris Flow: Fast-moving mixture of water, soil, and rock flowing like a fluid down a slope.
- Earth Flow: Slow, steady movement of saturated, fine-grained soil resembling a viscous fluid.
- Mudflow: Rapid movement of a water-saturated mixture of mud, silt, and clay.
- Creep: Slow, gradual movement of soil and rock downslope, often imperceptible over short periods.
Causes of Landslides
Natural Factors
- Heavy Rainfall: Saturates the soil, reducing stability and triggering landslides. Example: 2018 Kerala floods.
- Earthquakes: Seismic activity destabilizes slopes, causing landslides. Example: 2009 Kinnaur landslide.
- Snow Melting: Rapid snowmelt increases water flow, weakening soil stability.
- Undercutting of Slopes: Flooding erodes the base of slopes, leading to instability.
Anthropogenic Factors
- Excavation: Removes soil and rock, destabilizing slopes. Example: 2019 Munnar landslide.
- Deforestation: Removing vegetation that stabilizes soil increases landslide risk. Example: 2018 Kodagu landslides.
- Overgrazing: Destroys vegetation, leading to soil erosion and landslides.
Impacts of Landslides
- Loss of Life and Property: Example: 300 deaths in Wayanad landslides.
- Infrastructure Damage: Destruction of roads, bridges, and power lines.
- Economic Losses: Disruption of livelihoods, trade, and tourism. Example: Impact on Darjeeling’s tea industry.
- Environmental Degradation: Causes soil erosion, deforestation, and water pollution.
- Disaster Relief and Rehabilitation: Diverts government resources for rescue and relief efforts.
- Psychological Impact: Causes trauma and distress among survivors and communities.
Notable Landslides in India
- Guwahati, Assam (1948): Over 500 deaths due to heavy rain-triggered landslides.
- Darjeeling, West Bengal (1968): Landslides caused by floods killed over 1000 people.
- Malin, Maharashtra (2014): Heavy rainfall-triggered landslide killed around 151 people.
- Mapla, Uttarakhand (1998): Series of landslides killed over 380 people.
- Kedarnath, Uttarakhand (2013): Landslides triggered by rain and floods killed over 5700 people.
- Wayanad, Kerala (2024): Recent landslides caused significant loss of life and property damage.
Regions with High Landslide Incidence
- Kerala: Highest number of landslides recorded from 2015-2022, particularly during the monsoon.
- Maharashtra: Western Ghats regions prone to landslides.
- Northeastern India: Mizoram, Tripura, Nagaland, and Arunachal Pradesh are highly susceptible due to their terrain and rainfall.
- Himalayan Region: Uttarakhand, Himachal Pradesh, and Jammu and Kashmir frequently experience landslides due to their mountainous terrain.
Landslides in the Western Ghats
- Causes: Deforestation, land use change, unsustainable agriculture practices, climate change, unscientific infrastructure development, urbanization, and mining activities.
- Comparison with Himalayas: Western Ghats have lower altitude and less steep slopes, older rock formations, and experience frequent landslides during the monsoon. Himalayas have higher altitude, steeper slopes, younger rock formations, and landslides triggered by rainfall, snowmelt, and earthquakes.
Mitigation Measures
- Reforestation and Afforestation: Stabilizes soil and reduces water runoff.
- Sustainable Land Use Management: Regulates land use to prevent deforestation and unplanned construction.
- Early Warning Systems: Uses meteorological data to alert people before landslides occur.
- Engineering Interventions: Constructs retaining walls and drainage channels to stabilize slopes.
- Disaster Preparedness: Regular drills, evacuation plans, and community training.
- Community Participation: Involves communities in awareness campaigns and training.
- Research and Monitoring: Conducts studies to understand landslide patterns and vulnerabilities.
- Infrastructure Development: Builds landslide-resistant infrastructure with proper drainage systems.
Way Forward
- Strengthened Disaster Management: Uses advanced monitoring systems to predict landslides.
- Comprehensive Land Use Planning: Enforces strict land use regulations in sensitive regions.
- Investment in Research: Funds research on landslide susceptibility and early warning models.
- Community-Based Disaster Risk Reduction: Establishes disaster management committees for awareness and evacuation.
- Sustainable Development: Advocates for afforestation and sustainable agriculture.
- Resilient Infrastructure Development: Adopts landslide-resistant designs for road construction and other infrastructure.
By implementing these measures, India can mitigate the impacts of landslides and enhance the resilience of affected communities.
