Landslides in India - Gokulam Seek IAS Academy

Syllabus
GS Paper I – Important Geophysical phenomena such as earthquakes, Tsunami, Volcanic activity, cyclone etc., geographical features and their location-changes in critical geographical features (including water-bodies and ice-caps) and in flora and fauna and the effects of such changes.
GS Paper III – Disaster and disaster management.

Context
Several people died in recent massive landslides in Wayanad, Kerala.

Landslides in India

Table of Contents

Introduction

Landslides have recently claimed several lives in Wayanad, Kerala, following extremely heavy rainfall. This district, located in the Western Ghats, is particularly prone to such disasters. The Western Ghats, second only to the Himalayas in terms of landslide vulnerability in India, frequently experience landslides during the monsoon season. The region’s high soil depth and steep slopes contribute to this risk, as they allow for greater water retention and increased porewater pressure, ultimately triggering landslides.

Landslides

Definition

A landslide is the downward movement of rock, soil, and debris on a slope: This can range from small shifts to large, destructive events.
Landslides occur when gravity forces pushing on hill slope material exceed the frictional forces holding the material in place: This imbalance causes slope failure.
Approximately 0.42 million sq. km (12.6% of land area), excluding snow-covered areas, is prone to landslide hazard in India: This data is provided by the Geological Survey of India (GSI).

Types of Landslides

Falls: This type of landslide involves the collapse of material from a cliff or steep slope, which then falls down the slope and collects near the base.
Topples: In this type of landslide, the falling mass undergoes forward rotation and movement around an axis or point at or near the base.
Slides: This type of landslide features a distinct zone of weakness that separates the moving material from a more stable underlying material.
- Rotational Slide: Here, the surface of rupture is curved concavely upward, and the slide movement of the falling mass is rotational about an axis parallel to the ground surface and transverse across the slide.
- Translational Slide: In this type, the landslide mass moves along a roughly planar surface with little rotation or backward tilting.
Flows: This type of landslide involves the movement of material down a slope in the form of a fluid.
- Mud Flow: This involves the movement of wet material, primarily composed of sand, silt, and clay-sized particles.
- Debris Flow: Loose soils, rocks, and organic matter combine with water to form a slurry that flows down a slope.
- Rock Flow or Rock Avalanches: This specific type of landslide involves the flow of rock material downslope.

Causes of Landslides

Primary cause

Gravitational Forces: These are the primary cause of landslides, constantly pulling materials on slopes downward.
- When gravity exceeds the shear strength of geomaterials like rocks, sand, silt, and clay, the slope fails, resulting in the downhill movement of these materials.

Natural Triggers

Rainfall: Prolonged or intense rainfall increases soil water content, reducing cohesion and adding weight to slopes, making them more prone to failure.
Earthquakes: Earthquakes destabilize slopes by shaking the ground and weakening the structural integrity of geomaterials, especially in tectonically active regions like the Himalayas.
Erosion: Natural processes such as river or wave action can erode the base of slopes, undermining their stability. Coastal areas are particularly susceptible to landslides due to wave-induced erosion.
Volcanic Eruptions: Ash and debris deposited by volcanic eruptions overload slopes, while the accompanying seismic activity causes instability, triggering landslides.

Hydrological Factors

Groundwater Movement: Groundwater movement can contribute to landslide risk. Water can seep through porous materials, increasing pore pressure and reducing effective stress, thereby weakening the slope.
Soil Piping and Landslides: Soil piping, or pipe erosion, causes subsurface erosion by creating underground channels, leading to rapid soil settlement and landslides. Recent examples include the 2024 landslide in Puthumala, Wayanad, and the 2018 landslides in Idukki, Kerala.

Anthropogenic Influences

Deforestation: This has removed vegetation, destabilizing slopes by eliminating tree roots that provide natural reinforcement and water drainage.
Construction and Land Use Changes: Activities such as mining, road construction, and urban development have disrupted natural drainage and load distribution, increasing landslide risks.
- Historical deforestation for agriculture and tea plantations by the British has weakened soil stability, making the region (Western Ghats) more prone to landslides during heavy rains.
Infrastructure Development: Tourism and infrastructure development, including resorts, artificial lakes, and construction activities, have intensified land pressure and disrupted natural drainage, increasing landslide risks.

Geological Factors

Geological Composition: Geological factors, such as the composition, structure, and weathering state of materials, significantly affect slope stability.
- The Western Ghats have a fragile ecology with steep slopes and dual-layered terrain, making them prone to landslides when rainwater saturates the soil, increasing its weight and reducing stability.

Other Factors

Defunct Quarries: The presence of quarries in the vicinity, even after they have ceased operations, has also contributed to soil destabilization. The vibrations and shockwaves from these activities could weaken the geological structure, making the area more prone to landslides during heavy rains.
Encroachment in Vulnerable Terrains: Recently, humans have been encroaching on landslide-prone areas such as hilly terrains. This has led to increased construction activities in these areas and increased chances of landslides.
Climate Change: Climate change caused by various anthropogenic activities has led to abrupt alterations in precipitation patterns and increased frequency of extreme weather events.

Impact of Landslides

Human and Social Impact

Loss of Lives: Landslides result in the loss of human and animal lives.
Displacement: The aftermath often leads to the displacement of local communities.
Temporary Loss of Livelihood: Poor people often face a temporary loss of livelihood due to the destruction of crops and vegetation.
Demographic Impact: Landslides can lead to the relocation of populations to other areas.
Transportation Disruption: Landslides frequently block transportation routes, causing significant repercussions.
Traffic Jams: Obstruction of vehicular movement leads to traffic jams and other related issues.
Geographical Isolation: Frequent disruptions lead to geographical isolation and perpetuate under-development.

Environmental and Economic Impact

Damage to Infrastructure: Homes, roads, and other properties suffer significant damage.
Agricultural Impact: Landslides can bury or wash away agricultural land, severely affecting farming activities.
Landscape Alteration: The movement of large masses can change the natural landscape, impacting ecosystems and watercourses.
Increased Sediment Load: Landslides increase the sediment load in rivers, which can lead to floods.
Reduced Project Lifespan: The added silt load to reservoirs reduces the effective life of hydroelectric and multipurpose projects.
Loss of Cultivable Land: There is a significant loss of cultivable land and infrastructure.
Environmental Impact: Erosion and soil loss are major environmental consequences.

Landslide Atlas of India by ISRO

ISRO has recently released the Landslide Atlas of India. Here are some prominent statistics regarding landslides in India:

Landslide-Prone Areas: Excluding snow-covered areas, around 12.6 percent of India’s geographical land area is prone to landslides.
- Global Ranking: India is among the top 5 landslide-prone countries globally, along with China, the US, Italy, and Switzerland.
- Distribution of Reported Landslides:
  - 66.5% in the Northwestern Himalayas
  - 18.8% in the Northeastern Himalayas
  - 14.7% in the Western Ghats
- Economic Loss: According to the Geological Survey of India, the economic loss due to landslides may amount to as much as 1% to 2% of the Gross National Product (GNP) in many developing countries.

Major Landslide-Prone Areas in India

Northeastern Region: Comprises about 50 percent of the total landslide-prone areas in India.
Himalayan Region: Areas of Uttarakhand, Himachal Pradesh, and Jammu & Kashmir.
Western Ghats: Areas of Maharashtra, Goa, Karnataka, Kerala, and Tamil Nadu. Nearly 17,000 sq. km of area in Kerala, mostly on the western side of the Western Ghats, is mapped as landslide-prone.
Eastern Ghats: The Araku region in Andhra Pradesh.

Other Major Landslides in India

Kedarnath, Uttarakhand (2013)
Pettimudi, Kerala (2020)
Mumbai, Maharashtra (2021)
Tupal, Manipur (2022)
Raigarh, Maharashtra (2023)
Aizawl, Mizoram (2024)
Shirur, Karnataka (2024)

Key Initiatives to mitigate Landslides

Government Schemes and Initiatives

National Landslide Risk Management Strategy (2019): The National Landslide Risk Management Strategy (2019)is a comprehensive approach that addresses hazard mapping, monitoring, early warning systems, awareness programs, capacity building, policies, and stabilization measures.
Landslide Risk Mitigation Scheme (LRMS): The Landslide Risk Mitigation Scheme (LRMS), currently under preparation, aims to provide financial support for tailored landslide mitigation projects in vulnerable states. It focuses on disaster prevention, mitigation strategies, and research and development for monitoring critical landslides. This initiative will also contribute to the establishment of an Early Warning System (EWS) and enhance capacity-building efforts.
Flood Risk Mitigation Scheme (FRMS): The Flood Risk Mitigation Scheme (FRMS) is a forthcoming initiative aimed at developing flood shelters, river basin-specific early warning systems, and digital elevation maps for flood preparedness and evacuation.
Landslide Atlas of India: The Landslide Atlas of Indiais a detailed resource documenting landslide events in the country’s vulnerable areas and includes damage assessments for certain sites. Developed by the National Remote Sensing Centre (NRSC) under the Indian Space Research Organisation (ISRO), it offers important information and insights related to landslides in India.
National Landslide Susceptibility Mapping (NLSM) Programme: Under the National Landslide Susceptibility Mapping (NLSM) Programme, the Geological Survey of India (GSI) has completed landslide susceptibility mapping.
Indian Landslide Susceptibility Map (ILSM): IIT Delhi has created the first high-resolution Indian Landslide Susceptibility Map (ILSM).
National Landslide Forecasting Centre (NLFC): The National Landslide Forecasting Centre (NLFC) has been launched in Kolkata. It aims to operationalize the regional Landslide Early Warning System (LEWS) nationwide by 2030.

NDMA Guidelines for Landslide Disaster Management

The National Disaster Management Authority (NDMA) has established comprehensive guidelines for managing landslide disasters, covering hazard assessment, risk management, structural and non-structural measures, institutional mechanisms, financial arrangements, and community participation.

Landslide Hazard, Vulnerability & Risk Assessment: This involves delineating areas susceptible to landslide hazards and assessing the resources at risk.
Early Warning Systems for Landslides: Continuous monitoring of movements, development of stresses, and the transmission of this data at regular intervals are crucial for early warning systems.
Investigations for Landslide Risk Assessment: Multi-disciplinary investigations of landslide risk assessment lead to the formulation of standards to mitigate the impact of landslides.

Challenges associated with Landslides

Major challenges

Loss of Life and Injury: Landslides can result in fatalities and serious injuries to individuals in affected areas. The sudden nature of landslides often leaves little time for evacuation.
Displacement of Communities: Landslides can lead to the displacement of populations, forcing communities to relocate. This can disrupt social structures and lead to long-term socio-economic challenges.
Damage to Infrastructure: Critical infrastructure such as roads, bridges, and buildings can be severely damaged or destroyed, leading to significant economic losses and hampering rescue and relief operations.
Economic Impact: The cost of repairing damaged infrastructure and providing humanitarian aid can be substantial. Additionally, landslides can disrupt local economies, particularly in areas reliant on agriculture and tourism.
Environmental Degradation: Landslides can lead to soil erosion, loss of vegetation, and habitat destruction, adversely affecting biodiversity and ecosystem services.
Remote Locations: Many landslide-prone habitations are in remote locations in the hinterlands of the Himalayas, North-Eastern regions, and the Western and Eastern Ghats. This makes it difficult for district administration and NDRF and SDRF teams to reach these locations quickly.
Adverse Weather Conditions: Most landslides occur during the rainy season when weather conditions, coupled with poor visibility, make it difficult for relief operations to continue using helicopters.

Predicting Landslides is difficult. Why?

Complexity of Geomaterials: The subsurface consists of various rocks and particulate materials with differing strengths, making it difficult to assess stability accurately.
Insufficient Data: Detailed three-dimensional mapping of geomaterials is required, but current technology often relies on limited data from select locations, leading to uncertainty.
Identifying Weak Points: Critical weak points, such as fractures in rock masses, can be easily overlooked, contributing to prediction inaccuracies.
Estimating Size and Runout: Determining the exact size of a potential landslide and its runout distance is challenging, complicating risk assessments.
Timing Predictions: Forecasting when landslides will occur is difficult, akin to predicting weather or seismic activity, which involves inherent uncertainties.
Environmental Variability: Changes in rainfall patterns, seismic activity, and human activities can all influence slope stability, adding further complexity to predictions.
Technological Limitations: Current sensors and models may not provide the necessary precision for accurate predictions, especially in remote or inaccessible areas.

Preventive Measures

Technological and Structural Measures

Building Resilience: Setting up a network of sensors for real-time monitoring and data collection.
- Assessment of Rainfall Thresholds: Evaluating rainfall thresholds for soil saturation in different areas.
- Mapping Landslide Routes: Identifying the routes that landslides are likely to take after being triggered.
- Creating Route Maps: Marking areas that should be out of bounds for settlements or activities.
Harnessing Technology for Vigilant Monitoring: Utilizing web-based sensors like rain gauges, piezometers, inclinometers, extensometers, InSAR (Interferometric Synthetic Aperture Radar), and total stations to monitor vulnerable areas, focusing on densely populated and urbanized zones.
Integrated Early Warning System (EWS): Developing a comprehensive EWS using Artificial Intelligence (AI) and Machine Learning (ML) algorithms to predict and alert communities about impending hazards, providing valuable time for precautionary measures.
Soil Nailing and Hydroseeding for Landslide Prevention: The State highways department in Kerala is tackling landslide issues in the Nilgiris with soil nailing and hydroseeding.
- Soil Nailing: Reinforces soil.
- Hydroseeding: Promotes plant growth with a mix of seeds, fertilizer, and water. This approach includes planting five grass species and maintaining the vegetation to reduce the environmental impact of road infrastructure.
Building Codes and Evaluation: Mapping towns and assessing load-bearing capacities to develop robust building codes for safe construction in hazard-prone areas. Enforcing strict land use restrictions in these areas to prevent activities that could destabilize the soil.
Regulation & Enforcement: State governments/SDMAs will adopt the model techno-legal framework for ensuring compliance with land use zoning and landslide safety issues in all development activities and plans.

Awareness, Preparedness, and Environmental Considerations

Sustainable Socio-Economic Progress: Recognizing the region’s valuable natural resources, such as glaciers, springs, minerals, energy sources, and medicinal plants, for sustainable socio-economic development. Balancing resource utilization with ecological conservation for long-term viability.
Environmental Considerations: Safeguarding ecosystems through sustainable practices and responsible resource use.
- Urban Planning: Implementing thoughtful urban planning in mountainous areas, restricting extensive construction and managing drainage and slope excavation scientifically.
- Retaining Walls: Using retaining walls to support soil and restore ecological balance through reforestation and soil conservation efforts.
Awareness and Preparedness: Conducting comprehensive awareness campaigns targeting different groups of people living in landslide-prone areas systematically.
Capacity Development (Including Education, Training, and Documentation):
- Curriculum Introduction: Introducing disaster management, including landslides, in school curriculums.
- Administrator Training: Training administrators to plan, respond, and mitigate the impact of landslides.
- Technical Expertise: Developing adequate technical expertise in technical institutes located in vulnerable areas on various subjects related to landslide management.
Immediate Response: Putting in place Standard Operating Procedures (SoP) to ensure coordinated and sustained action from various agencies in the aftermath of landslides.
Research & Development (R&D): Encouraging, promoting, and supporting R&D activities to address current challenges, offer solutions, and develop new investigation techniques, with the application of the latest developments in remote sensing, communications, and instrumentation technologies.

Conclusion

Landslides are a significant disaster in India with extensive consequences. As societies expand into vulnerable regions, a proactive approach to landslide prevention and mitigation is crucial. The measures outlined above can aid in this effort. The Wayanad landslides highlight the complex relationship between natural disasters and human activities. To mitigate risks and protect vulnerable communities, a multifaceted approach involving regulation, education, and scientific research is essential.

Additional Information

Differences Between Landslides in the Western Ghats and the Himalayan Region

Region	Causes
Western Ghats	– Concentrated Rainfall: Intense and concentrated rainfall during the monsoon season significantly contributes to landslides. – Overburdening of Hills: Excessive load on hills due to various activities increases the risk of landslides. – Mining and Quarrying: These activities destabilize the slopes, making them more prone to landslides. – Anthropogenic Activities: Agricultural activities, windmill projects, and other human interventions exacerbate the risk. – Forest Fragmentation: Dense vegetation on thin soil, coupled with forest fragmentation, leads to instability.
Himalayan Region	– High Seismicity: The region’s high seismic activity due to plate tectonic movements makes it highly susceptible to landslides. – Easily Erodible Sedimentary Rocks: The presence of easily erodible sedimentary rocks contributes to frequent landslides. – Young and Energetic Rivers: Rivers like the Ganga, Yamuna, and Jhelum, with high erodibility, further destabilize the region. – Heavy Downpour and Snowfall: Intense rainfall and snowfall add to the landslide risk. – Anthropogenic Factors: Deforestation, jhum cultivation, road construction, and other human activities increase the likelihood of landslides.

Recommendations of Various Committees on Western Ghats

Western Ghats Ecology Expert Panel, 2011 (Headed by Madhav Gadgil) (Read more here)

Ecologically Sensitive Areas (ESA): All of the Western Ghats should be declared as ESAs with only limited development allowed in graded zones.
Classification of ESAs: The Western Ghats should be classified into ESA 1, 2, and 3, with ESA-1 having the highest priority where almost all developmental activities are restricted.
Governance Approach: A bottom-to-top governance system, starting from Gram Sabhas, rather than a top-to-bottom approach.
Western Ghats Ecology Authority (WGEA): To be constituted as a statutory authority under the Ministry of Environment, Forest and Climate Change, with powers under Section 3 of the Environment (Protection) Act, 1986.
Criticism: The report was criticized for being more environment-friendly and not in tune with ground realities.

Kasturirangan Committee, 2013

Balanced Approach: Sought to balance development and environmental protection, in contrast to the Gadgil report.
ESA Coverage: Only 37% of the total area of the Western Ghats to be brought under ESA.
Mining Ban: Complete ban on mining, quarrying, and sand mining in ESAs.
Power Projects: No thermal power projects to be allowed; hydropower projects to be allowed only after detailed study.
Polluting Industries: Red industries, which are highly polluting, to be strictly banned.
Pro-Farmer Approach: Exclusion of inhabited regions and plantations from the purview of ESAs.

References: IE | IE(a)

Related PYQ

Q1. Differentiate the causes of landslides in the Himalayan region and Western Ghats. (UPSC CSE – 2021 Mains)

Q2. The Himalayas are highly prone to landslides.” Discuss the causes and suggest suitable measures of mitigation. (UPSC CSE – 2016 Mains)

Practice Question

Discuss the causes of frequent landslides in the Western Ghats and suggest suitable mitigation strategies. (250 words)