Landslides in India

Context (TH | IE | HT): Landslides are sudden movements of rock, boulders, earth, or debris down a slope under the impact of gravity. In July 2024, the Wayanad district in Kerala experienced severe landslides, which resulted in hundreds of deaths, property damage, and displacement of residents.

Types of Landslides

Based on the materials involved

Rock slide: Movement of bedrock down a slope, typically involving detached rock masses.
Debris slide: Rapid downslope movement of loose, unconsolidated material like soil, rock fragments, organic matter, etc.
Soil slide: Movement of saturated, loose soil that may involve a mix of soil and vegetation.
Loose mudslide: Flow of loosely bound mud that becomes mobilised and moves downslope.

Based on the movement of material

Fall: Sudden free fall of rock or debris from a steep slope or cliff.
Topple: Rotation of rock/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 a rotational component.
Translational slide: Downslope movement of material along a planar or nearly planar slip surface.

Based on the flow of material

Debris flow: Fast-moving mixture of water, soil, and rock that flows like a fluid down a slope.
Earth flow: Slow, steady movement of saturated, fine-grained soil/sediment resembling a viscous fluid.
Mudflow: Rapid, fluid movement of a water-saturated mixture of mud, silt, and clay.
Creep: Slow, gradual downslope movement of soil and rock due to gravity, often imperceptible over short periods.

Causes Behind Landslides

Natural Factors

Heavy Rainfall: Heavy rain saturates the soil, reducing stability and triggering landslides. E.g., the 2018 Kerala floods caused numerous landslides in the Western Ghats due to intense rainfall.
Earthquakes: Seismic activity shakes the ground, destabilising slopes and causing landslides, such as the 2009 Kinnaur landslide.

Snow Melting: Rapid snowmelt increases water flow, weakening soil stability.
Undercutting of Slopes Due to Flooding: Flooding erodes the base of slopes, making them unstable. E.g., landslides in the Western Ghats, exacerbated by flooding.

Anthropogenic Factors

Excavation: This removes soil and rock, destabilising slopes. For example, construction and excavation activities worsened the 2019 Munnar landslide in Kerala.
Cutting of Hills and Trees: Deforestation removes vegetation that stabilises soil, increasing landslide risk. For example, hill cutting and deforestation aggravated the 2018 Kodagu landslides in Karnataka.
Overgrazing by Cattle: Overgrazing destroys vegetation, leading to soil erosion and landslides. For example, overgrazing in the Western Ghats increases soil erosion, contributing to landslide risk.

Impacts of Landslide

Loss of life and property: For instance, around 300 people lost their lives in Wayanad landslides.
Infrastructure damage: Critical infrastructure like roads, bridges, power lines, etc. are destroyed.
Economic losses: Disrupt livelihoods, trade, and tourism. The landslides in Darjeeling, West Bengal, have impacted the region’s tea industry.
Environmental degradation: Causes soil erosion, deforestation, and pollution of water bodies, leading to long-term environmental consequences.

Disaster relief and rehabilitation: Government resources are diverted for rescue, relief, and rehabilitation efforts after landslides, impacting other development priorities.
Psychological impact: Landslides can cause severe trauma and psychological distress among survivors and affected communities.

The Worst Landslides in India

Guwahati, Assam (1948): Over 500 people lost their lives when an entire village was buried under a landslide triggered by heavy rains.
Darjeeling, West Bengal (1968): A massive landslide caused by floods killed over 1000 people and divided a 60 km long highway into 91 parts.
Malin, Maharashtra (2014): Heavy rainfall triggered a landslide that claimed the lives of around 151 people, with 100 others missing.
Mapla, Uttarakhand (1998): A series of landslides over seven days wiped out an entire village, resulting in the death of over 380 people.
Kedarnath, Uttarakhand (2013): Unprecedented rain and floods triggered massive landslides, leading to the death of over 5700 people and the destruction of thousands of villages.
Wayanad, Kerala (2024): Recent landslides in the Wayanad district caused significant loss of life and property damage, highlighting the ongoing threat of landslides in India.

States and districts with the Highest Incidence of Landslides in India

Source: The Hindu

Kerala: Witnessed devastating landslides, particularly during the monsoon and topped the list with the highest number of landslides recorded from 2015-2022.
Maharashtra: Certain regions, like the Western Ghats, are prone to landslides.

Northeastern India

Mizoram: Its unique geographical and geological conditions make it highly susceptible to landslides.
Tripura: Susceptible to landslides due to its hilly terrain and heavy rainfall.
Nagaland: Faces significant landslide challenges, especially during the monsoon season.
Arunachal Pradesh: The state’s mountainous landscape makes it prone to landslides.

Himalayan Region

Uttarakhand: Known for its mountainous terrain, Uttarakhand has experienced numerous landslides.
Himachal Pradesh: Another Himalayan state facing landslide risks due to its geographical features.
Jammu and Kashmir: The region’s hilly topography contributes to frequent landslide occurrences.

Read > Indian Landslide Susceptibility Map.

Landslides in Western Ghats

The Western Ghats, a biodiversity hotspot, are also prone to landslides due to their unique geographical and climatic conditions.

Causes of Increased Landslides in the Western Ghats

Deforestation and Land Use Change: Large-scale conversion of forests into plantations, especially monoculture plantations like rubber and tea, has weakened the soil structure, making it susceptible to erosion and landslides.
Unsustainable Agriculture Practices: Shifting cultivation and steep slope agriculture have led to soil erosion, loss of vegetation cover, and increased landslide vulnerability.
Climate Change and Extreme Weather Events: Increased frequency and intensity of rainfall due to climate change have triggered landslides.
Unscientific Infrastructure Development: Construction of roads, dams, and tunnels without proper environmental impact assessment has destabilised slopes and increased landslide risks.
Urbanization and Population Pressure: Encroachment into hill slopes for residential and commercial purposes has led to the removal of vegetation and increased load on the slopes.
Mining and Quarrying Activities: Illegal and unscientific mining and quarrying have weakened the rock structure and destabilised slopes.

Comparison between landslides in the Western Ghats and the Himalayas

Factor	Western Ghat	Himalayas
Topography	Lower altitude, less steep slopes	Higher altitude, steeper slopes
Geological formations	Older, more stable rock formations (generally)	Younger, weaker rock formations
Rainfall	High Rainfall: Heavy monsoon rains contribute to frequent landslides.	Variable Rainfall: Heavy monsoon rains in foothills and significant snowfall in higher elevations.
Landslide Frequency	High Frequency: Frequent landslides during monsoon season; numerous events annually.	Very High Frequency: Frequent landslides year-round due to intense rainfall and seismic activity.
Landslide Triggers	Monsoon Rains, Deforestation, Construction: Heavy rains, human activities like deforestation and construction.	Rainfall, Snowmelt, and Earthquakes: Intense rainfall, snowmelt, and seismic activity are major triggers.
Mitigation Measures	Afforestation, Drainage Systems, Land Use Planning: Focus on vegetation and engineering solutions.	Slope Stabilization, Early Warning Systems, Engineering Solutions: Emphasis on monitoring and robust engineering practices.
Notable Events	2018 Kerala Floods, 2019 Munnar Landslide: Significant landslide events caused by heavy rains and human activities	2013 Uttarakhand Floods, 2020 Chamoli Landslide: Major landslide events influenced by heavy rainfall, snowmelt, and earthquakes.
Measures Attempted to Conserve Western Ghats Madhav Gadgil Committee. Kasturirangan Committee. October 2018 notification Ecological Sensitivity Classification Protected Areas and Wildlife Sanctuaries Research and Monitoring Environmental Impact Assessment (EIA)

Landslide Mitigation Measures

Reforestation and Afforestation: Planting native tree species helps stabilize soil, reduce water runoff, and enhance the overall ecosystem.
Sustainable Land Use Management: Implementing strict regulations on land use, especially in hilly areas, to prevent deforestation, unplanned construction, and unsustainable agriculture.
Early Warning Systems: Developing a robust early warning system using rainfall data, soil moisture sensors, and other meteorological parameters to alert people before a landslide occurs.
Engineering Interventions: Constructing retaining walls, terraces, and drainage channels to stabilise slopes and prevent soil erosion.
Disaster Preparedness and Response: Conduct regular mock drills and evacuation plans and train local communities on disaster response measures.
Community Participation: In landslide mitigation efforts through awareness campaigns, training, and providing alternative livelihood options.
Research and Monitoring: Conduct scientific studies to understand landslide patterns and vulnerabilities and develop advanced monitoring systems.
Infrastructure Development: Constructing roads, bridges, and other infrastructure with landslide-resistant designs, avoiding vulnerable areas, and incorporating drainage systems.

Way Forward

Strengthened Disaster Management and Early Warning Systems: The Kerala State Disaster Management Authority uses advanced monitoring systems, including rainfall gauges, soil moisture sensors, and remote sensing in the Idukki district to predict landslides and enable timely evacuations.
Comprehensive Land Use Planning and Zoning: Karnataka enforces strict land use regulations in the Western Ghats, designating buffer zones and no-development areas to restrict construction in ecologically sensitive regions.
Investment in Research and Technology: The Indian Institute of Science (IISc) Bangalore funds research on landslide susceptibility mapping and develops early warning models for the Western Ghats.
Community-Based Disaster Risk Reduction: The Nilgiri District Administration in TN has established community-based disaster management committees for awareness, mock drills, and evacuation.
Sustainable Development and Ecosystem Restoration: The Western Ghats Ecology Expert Committee (WGEC) advocates afforestation and sustainable agriculture to protect ecosystems and mitigate risks.
Infrastructure Development with Resilience: The National Highways Authority of India (NHAI) adopts landslide-resistant designs for road construction, including retaining walls, tunnels, and effective drainage systems.