Landslides & Avalanches: India's Shifting Terrains

Landslides and avalanches, often silent but swift killers, pose a significant and growing threat in India's mountainous regions, causing widespread destruction, loss of life, and disruption to connectivity. Their incidence is increasingly attributed to a complex interplay of natural geological processes and exacerbated by anthropogenic activities and climate change.

Explore More

Introduction & Overview

Landslides and avalanches are frequent and devastating hazards, particularly in India's mountainous regions, causing significant loss of life, extensive damage to infrastructure, and disruption of essential services. These events are often hybrid disasters, triggered by natural factors but exacerbated by human activities.

Understanding their causes, identifying vulnerable regions (Himalayas, Western Ghats), and analyzing their impacts is crucial for effective disaster management. This topic delves into comprehensive mitigation strategies (hazard zonation, slope stabilization), essential preparedness measures (early warning systems, public awareness), and highlights key case studies like the Uttarakhand floods and Joshimath land subsidence, underscoring the imperative for an integrated, proactive, and sustainable approach guided by NDMA guidelines.

"The mountains are calling and I must go." - John Muir. But with awareness and respect for their shifting nature.

Mountain landscape with subtle erosion

4.6.1. Causes of Landslides & Avalanches

Natural Causes

  • Heavy Rainfall: Most common trigger in India, saturating soil, reducing shear strength.
  • Earthquakes: Seismic tremors destabilize slopes, trigger landslides or avalanches.
  • Erosion: Natural erosion by rivers, glaciers, or wind undercuts slopes.
  • Geological Factors: Weak rock formations, steep slopes, natural faults.
  • Snowmelt: Rapid melting saturates soil, contributes to slope failure or triggers avalanches.
  • Glacial Melt: Increased melt forming new lakes or increasing water flow (GLOFs).

Anthropogenic (Human-induced) Causes

  • Deforestation: Removal of tree cover reduces soil cohesion and moisture retention.
  • Road Construction: Unscientific cutting of slopes, improper drainage, dumping debris.
  • Mining: Undercutting slopes, waste disposal, blasting vibrations.
  • Unplanned Settlements/Urbanization: Construction on unstable slopes, poor drainage.
  • Changes in Drainage Patterns: Altering natural water flow due to construction.
  • Hydropower Projects: Excavation, blasting, changes in water flow patterns.
  • Climate Change: Intensifies rainfall, increases glacial melt, alters permafrost, exacerbating natural triggers.

Source: NDMA Guidelines for Landslide and Avalanche Management; Geological Survey of India (GSI).

4.6.2. Vulnerable Regions

Himalayan Region

The most vulnerable region: Jammu & Kashmir, Ladakh, Himachal Pradesh, Uttarakhand, Sikkim, and North-Eastern states (Arunachal Pradesh, Darjeeling hills). Characterized by young, fragile geology, steep slopes, high seismic activity, heavy rainfall, and increasing human intervention.

Western Ghats

Highly susceptible due to steep slopes, heavy monsoon rainfall, and human activities (deforestation, quarrying, unplanned development). Includes parts of Maharashtra, Goa, Karnataka, Kerala.

North-Eastern India

States like Assam, Meghalaya, Arunachal Pradesh, Nagaland, Mizoram, Tripura, Manipur, and Sikkim, due to heavy rainfall, fragile geology, and high seismic activity.

Source: GSI, NDMA.

4.6.3. Impact of Landslides & Avalanches

Infrastructure Damage

Destruction of roads, railways, bridges, power lines, communication networks, houses, and buildings.

Loss of Life & Injury

Direct casualties from falling debris, burial, or being swept away. High risk to communities.

Blocked Roads & Disruption

Landslides frequently block crucial mountain passes, disrupting transport, isolating communities, hindering relief.

Economic & Environmental Loss

Damage to property, agricultural land, tourism, soil erosion, sedimentation of rivers, destruction of forests. High reconstruction costs.

Secondary Hazards

Landslides can block rivers, creating temporary lakes (landslide lakes), which can burst and cause devastating flash floods (e.g., GLOF-like events). Avalanches can engulf villages and block roads.

Displacement & Trauma

Forced evacuation and displacement of populations, leading to psychological trauma and disruption of livelihoods.

Source: NDMA.

4.6.4. Mitigation Strategies

Landslide Hazard Zonation Mapping

Scientific mapping of areas prone to landslides based on geology, topography, rainfall, and past events. Informs land-use planning and development activities. (Done by GSI).

Drainage Management

Improving surface and subsurface drainage on slopes to prevent water saturation, which is a major trigger.

Afforestation/Reforestation

Planting trees on vulnerable slopes to bind soil with roots and prevent erosion. Large-scale tree planting in vulnerable hilly areas.

Regulation of Construction

Strict regulation and monitoring of road construction, tunneling, and building activities in fragile mountainous regions, adhering to environmental norms.

Slope Stabilization Techniques

Bio-engineering

Using vegetation (trees, grasses, shrubs) to stabilize slopes by binding soil with roots and reducing erosion. Eco-friendly and sustainable method.

Terracing

Creating stepped platforms on slopes to reduce erosion and runoff velocity, particularly effective in agricultural areas.

Retaining Walls/Gabion Walls

Construction of structural barriers (concrete, stone, wire mesh filled with rocks) to support unstable slopes and prevent mass movement.

Rock Bolting/Netting

Anchoring unstable rock masses with steel bolts or covering slopes with wire mesh to prevent rockfalls and surface erosion.

Controlled Blasting

Regulating blasting activities in mining and construction to minimize ground vibrations and destabilization of surrounding areas.

Source: NDMA Guidelines on Landslides and Avalanches; GSI.

4.6.5. Preparedness Measures

Early Warning Systems (EWS)

Rationale: Provide alerts based on rainfall thresholds, ground movement, or snowpack instability. Examples (e.g., Konkan Railway): Sensors (extensometers, rain gauges) along tracks/roads. Challenges: localized nature, difficult terrain for sensor deployment, complex data interpretation.

Public Awareness

Educating communities in vulnerable regions about warning signs (e.g., cracks in walls, new springs), safe evacuation routes, and what to do during an event.

Mock Drills & Contingency Planning

Regular drills for local communities and first responders. Detailed disaster management plans at district and local levels for resource allocation and response.

Source: NDMA Guidelines.

4.6.6. Key Case Studies

Uttarakhand Floods (2013)

  • Context: Catastrophic flash floods (cloudburst) and thousands of associated landslides in the Himalayan state of Uttarakhand.
  • Causes: Extreme rainfall, combined with rampant unplanned construction, deforestation, and hydropower projects in ecologically sensitive zones.
  • Impact: Massive loss of life, widespread destruction of roads, bridges, and religious sites, immense economic and environmental damage.
  • Lessons Learned: Highlighted devastating consequences of violating ecological norms, need for integrated land-use planning, resilient infrastructure, and robust EWS for hydro-geological hazards in the Himalayas. Accelerated shift towards environmental considerations in hill development.

Joshimath Land Subsidence (2023)

  • Context: Gradual sinking or collapsing of the ground, leading to large cracks in houses and roads in Joshimath town, Uttarakhand.
  • Causes: Primarily attributed to geological instability (town built on ancient landslide debris), aggravated by anthropogenic factors like unplanned construction, lack of proper drainage, rapid infrastructure development (roads, tunnels, hydropower projects), and increased load on the fragile substrata.
  • Response: Mass evacuation, declaration as disaster-prone area, scientific studies initiated.
  • Significance: Stark reminder of long-term, slow-onset impact of unsustainable development in the Himalayas and crucial need for rigorous geological assessment and eco-sensitive urban planning. Demonstrated risks of "induced geological hazards."

Source: NDMA reports, various government reports, media archives.

4.6.7. NDMA Guidelines for Landslide & Avalanche Management

Comprehensive Framework for Resilience

The National Disaster Management Authority (NDMA) has issued comprehensive guidelines for both Landslide Hazard Management (2009) and Avalanche Hazard Management (2009), providing detailed national frameworks.

Key Aspects Covered:

  • Hazard Zonation: Large-scale and site-specific mapping (by GSI).
  • Monitoring & Early Warning: Development of EWS.
  • Mitigation Measures: Structural (retaining walls, drainage) and non-structural (bio-engineering, land-use zoning, construction regulation).
  • Capacity Building: Training local communities, engineers, geologists.
  • Policy & Institutional Framework: Delineating roles of various ministries and agencies.
  • Community Awareness: Public education on safe practices.

These guidelines are crucial for guiding states and local authorities in implementing proactive and comprehensive strategies for managing these high-impact hazards in mountainous regions.

Source: NDMA Website.

Conclusion & Way Forward

Landslides and avalanches are complex, often hybrid disasters that pose a perennial threat to India's mountainous regions, intensified by climate change and unsustainable development. Effective management requires a fundamental shift towards a proactive, eco-sensitive, and multi-disciplinary approach.

Implementing rigorous Landslide Hazard Zonation Mapping, adopting appropriate slope stabilization techniques (structural and bio-engineering), enforcing strict land-use planning and construction regulations, and developing targeted early warning systems with last-mile connectivity are crucial.

By prioritizing sustainable development in fragile ecosystems and leveraging scientific understanding, India can significantly reduce the devastating impacts of these hazards, safeguarding its mountain communities and critical infrastructure.

Building Resilience Together

An integrated approach, combining scientific research, policy enforcement, and community participation, is key to future resilience.

Prelims-ready Notes

Causes

  • Natural: Heavy Rainfall (most common), Earthquakes, Erosion, Geological Factors, Glacial Melt.
  • Anthropogenic: Deforestation, Unscientific Road Construction, Mining, Unplanned Settlements, Hydropower Projects.

Vulnerable Regions

  • Himalayan region (most vulnerable): J&K, Ladakh, HP, Uttarakhand, Sikkim, NE.
  • Western Ghats, North-Eastern India.

Impact

  • Infrastructure damage, life loss, blocked roads (disruption).
  • Economic/environmental loss, secondary hazards (landslide lakes/GLOFs).

Mitigation

  • Landslide Hazard Zonation Mapping (GSI).
  • Slope Stabilization: Bio-engineering, Terracing, Retaining walls, Rock bolting.
  • Controlled Blasting, Drainage Management, Afforestation, Regulation of Construction.

Preparedness

  • Early Warning Systems (EWS): Automated sensors (e.g., Konkan Railway pilot).
  • Public Awareness, Mock Drills, Contingency Planning.

Case Studies & Guidelines

  • Uttarakhand Floods (2013): Landslides linked to extreme rain + unplanned dev.
  • Joshimath Land Subsidence (2023): Slow-onset, unstable geology + unplanned dev.
  • NDMA Guidelines: Comprehensive framework for Landslide/Avalanche Management.

Summary Table: Landslide & Avalanche Management in India

Aspect Key Features/Challenges India's Strategies/Initiatives Examples/Impact
Vulnerability Himalayan region (most), Western Ghats, NE India - fragile geology, heavy rainfall Landslide Hazard Zonation Mapping Uttarakhand (2013), Joshimath (2023)
Causes Natural (Rain, Earthquakes) & Anthropogenic (Deforestation, Roads, Settlements) Slope Stabilization (Bio-engineering, Terracing), Afforestation
Impact Infrastructure damage, Life loss, Blocked roads (disruption), Economic loss
Mitigation Reducing slope instability, proactive measures Retaining Walls, Drainage Mgmt, Controlled Blasting, Regulation of Construction Safer slopes, reduced future damages
Preparedness Early warning, Community readiness EWS (Konkan Railway), Public Awareness, Contingency Planning Timely evacuation, reduced casualties
Policy/Guidelines NDMA Guidelines for Landslide/Avalanche Management Comprehensive framework, emphasis on techno-legal regime National framework for proactive management

Mains-ready Analytical Notes

Landslides in the Himalayas: A Hybrid Disaster Exacerbated by Climate Change and Unsustainable Development

Context: The Himalayan region is highly vulnerable due to its young, fragile geology, steep slopes, and high seismicity. Climate change and unsustainable development are exacerbating this hazard.

Nature as a Hybrid Disaster:

  • Natural triggers: Heavy rainfall, earthquakes, natural erosion, weak geological formations.
  • Anthropogenic exacerbation: Deforestation, unscientific road/infrastructure construction (e.g., Char Dham road project concerns), mining, unplanned settlements, hydropower projects.

Impact:

Extensive damage to roads, bridges, communication lines (isolation), loss of life, destruction of homes/agricultural land, long-term economic disruption (tourism), environmental degradation. Can lead to cascading disasters (e.g., temporary lakes, flash floods).

Mitigation Strategies:

  • Landslide Hazard Zonation Mapping (GSI).
  • Slope Stabilization: Bio-engineering (vegetation), Engineering solutions (retaining walls, rock bolting, drainage).
  • Regulation of Construction: Strict enforcement of building codes and environmental regulations.
  • Afforestation & Reforestation.
  • Early Warning Systems (EWS) for rainfall thresholds and ground movement.

Conclusion: Landslides in the Himalayas are a severe and escalating hybrid disaster. Effective management requires a paradigm shift towards eco-sensitive development, strict land-use planning, robust mitigation, and continuous scientific monitoring, balancing development with ecological fragility.

The Joshimath Land Subsidence (2023): A Stark Reminder of Unscientific Development in Fragile Himalayan Ecosystems

Context: Gradual sinking of ground in Joshimath town, leading to cracks in buildings and roads.

Causes (Hybrid Nature):

  • Natural Vulnerability: Town built on ancient landslide debris, inherently unstable, high seismic zone. Natural springs contribute to erosion.
  • Anthropogenic Aggravation: Unplanned/unregulated construction (overloading), poor drainage allowing water seepage, large infrastructure projects (blasting, tunneling, vibrations), increased tourism load.

Impacts & Lessons Learned:

Displacement, destruction of homes, economic losses, psychological trauma. Critical lessons:

  • Respect Ecological Limits: Adhere to carrying capacity of sensitive regions.
  • Scientific Assessment: Rigorous geological and hydrological studies are mandatory.
  • Integrated Drainage Management: Prevent water saturation.
  • Scientific Infrastructure Development: Ensure rigorous EIA/GIA for all projects.
  • Eco-sensitive Urban Planning: Strict building codes, effective drainage.
  • Cumulative Impact Assessment: Assess combined impact of multiple projects.
  • "Build Back Better": Ensure resilient designs if resettlement occurs.

Conclusion: Joshimath is a painful reminder of neglecting scientific warnings and pursuing unsustainable development in the Himalayas. It demands a holistic, risk-informed, and environmentally sensitive approach to future development.

Avalanche Management in India: Challenges in Preparedness and Mitigation in High-Altitude Regions

Context: Avalanches are frequent in the upper Himalayan regions (J&K, Ladakh, HP, Uttarakhand, Sikkim), threatening military personnel, trekkers, and communities.

Causes:

  • Natural: Heavy snowfall, steep slopes, snowpack instability, temperature fluctuations, earthquakes.
  • Anthropogenic: Human triggers (skiers), road construction, military activity, climate change (rapid warming leading to instability).

Challenges in Preparedness & Mitigation:

  • Forecasting Difficulty: Complex terrain, variable snowpack, micro-climates.
  • Limited EWS: Difficult & costly sensor deployment in remote high-altitude regions.
  • Last-Mile Connectivity: Reaching remote communities with timely warnings.
  • Difficult Terrain for Structural Mitigation: Costly and complex implementation (snow nets, diversion structures).
  • Limited Bio-engineering Scope: At very high altitudes.
  • Climate Change: Warming temperatures lead to unstable snowpack.

Mitigation Strategies:

  • Avalanche Forecasting & Warning (SASE - DRDO).
  • Structural Measures: Snow Fences/Barriers, Snow Bridges/Galleries, Deflecting Structures.
  • Non-Structural: Land Use Zoning, Controlled Blasting, Route Planning, Public Awareness & Education.

Conclusion: Avalanche management faces unique challenges in India's high-altitude regions. Enhancing forecasting, robust EWS, continuous mitigation, and effective coordination between military/civilian agencies is crucial for safeguarding lives.

Current Affairs & Recent Developments (Last 1 Year)

NDMA Guidelines for GLOFs (Dec 2023)

Following Sikkim event, NDMA intensified focus on guidelines for Glacial Lake Outburst Floods (GLOFs), often associated with landslides and glacial retreat. Crucial step in managing hydrological/geological hybrids.

Uttarakhand Tunnel Collapse Rescue (Nov 2023)

Silkyara-Barkot tunnel collapse highlighted geological challenges of working in Himalayas and importance of geological assessments and slope stability during large infrastructure projects in vulnerable terrain.

Sikkim Flash Flood (Oct 2023)

Potentially exacerbated by an earthquake-induced landslide or GLOF, highlighting extreme vulnerability of Himalayan region to hydro-geological hazards. Emphasized enhanced landslide mitigation and GLOF EWS.

Joshimath Land Subsidence (Jan 2023 onwards)

Continued land subsidence led to evacuation and geological surveys. Emphasized severe consequences of unplanned settlements and large infrastructure projects on fragile Himalayan geology, highlighting anthropogenic causes.

Increased Focus on Hill State Development (Ongoing)

Discussions on balancing development with ecological sensitivity in Himalayan states, given incidents like Joshimath, have gained prominence. Links directly to unplanned settlements and road construction as anthropogenic causes.

UPSC Previous Year Questions (PYQs)

Prelims MCQs

  1. (2023) The term "Glacial Lake Outburst Flood (GLOF)" is sometimes mentioned in the news. It is primarily related to which of the following regions?
    (a) Western Ghats (b) Thar Desert (c) Himalayan Region (d) Coastal Plains of Odisha
    Answer: (c)
  2. (2022) Consider the following statements with reference to the 'Sendai Framework for Disaster Risk Reduction (2015-2030)':
    1. It is a legally binding international agreement. 2. Its primary goal is to substantially reduce disaster risk and losses... 3. It emphasizes strengthening disaster risk governance.
    Answer: (b) 2 and 3 only (Relevant to overall DRR for all hazards, including landslides).

Mains Questions

  1. (2018) Discuss the contemporary challenges to disaster management in India. (15 Marks)
    Direction: Challenges in landslide/avalanche management (unscientific development, climate change, poor EWS, Joshimath) are key challenges to overall DM.
  2. (2016) The frequency of earthquakes appears to have increased... Discuss the contemporary challenges of earthquake preparedness and mitigation in India. (12.5 Marks)
    Direction: Earthquakes can trigger landslides. Mitigation measures are common (land-use planning, safe construction).

Trend Analysis (UPSC Questions, Last 10 Years)

UPSC's questioning on Landslides & Avalanches has seen an increasing focus, reflecting the growing frequency and impact of these hazards, especially in the Himalayan region. The trend is towards analytical, multi-causal, and current affairs-linked questions.

Prelims Trend:

More nuanced questions testing causes (natural vs. anthropogenic), vulnerable regions, and specific mitigation/preparedness techniques. Strong emphasis on recent incidents (Joshimath, Sikkim flash flood) highlighting hybrid nature and slow-onset aspects.

Mains Trend:

Highly analytical and critical, requiring candidates to analyze the 'hybrid' nature, discuss specific case studies, evaluate effectiveness of mitigation/preparedness, integrate climate change linkages, and focus on policy implications for sustainable development in fragile ecosystems. Heavy integration of current affairs is crucial.

Original MCQs for Prelims

1. The **'Joshimath Land Subsidence'** event in Uttarakhand (2023), leading to cracks in buildings and roads, is primarily categorized as a:

  • (a) Rapid-onset meteorological disaster
  • (b) Induced hydrological disaster
  • (c) Slow-onset geological disaster
  • (d) Technological disaster due to dam failure

Answer: (c)

2. Which of the following human activities is considered a significant anthropogenic cause that can exacerbate landslides in hilly regions?

  1. 1. Large-scale afforestation programs.
  2. 2. Unscientific road construction and slope cutting.
  3. 3. Terracing for agricultural purposes.
  4. 4. Controlled blasting for mining or infrastructure projects.

Select the correct answer using the code given below:

  • (a) 1 and 3 only
  • (b) 2 and 4 only
  • (c) 1, 2 and 3 only
  • (d) 1, 2, 3 and 4

Answer: (b)

3. The phenomenon of **'land subsidence'**, recently observed in Joshimath, Uttarakhand, is characterized by:

  • (a) A sudden, rapid flow of snow, ice, and rock down a slope.
  • (b) A rapid overflow of water that submerges land due to heavy rainfall.
  • (c) The gradual sinking or downward settling of the ground surface.
  • (d) The emission of toxic gases from industrial facilities into the atmosphere.

Answer: (c)

Original Descriptive Questions for Mains

1. "Landslides in the Indian Himalayas are increasingly complex 'hybrid disasters', driven by a dangerous interplay of natural vulnerabilities and human-induced activities. Analyze the major natural and anthropogenic causes of landslides in the Indian Himalayan region, and discuss the comprehensive mitigation strategies required for sustainable development in these fragile ecosystems." (15 Marks)

2. "The recent land subsidence in Joshimath (2023) serves as a stark wake-up call, exposing the vulnerabilities of India's fragile mountain ecosystems to both natural processes and unsustainable developmental practices. Analyze the key factors contributing to this slow-onset disaster and discuss the critical lessons India must learn for ensuring disaster-resilient development in the Himalayan region." (20 Marks)