28 August 2024 – The Indian Express

Wayanad Landslides

Context/Why in News?

Recent Landslide Tragedy in Wayanad:

• Wayanad district in Kerala has recently experienced one of the most severe landslide-related disasters, exacerbated by extreme rainfall and the region’s delicate ecological balance. This event draws parallels to the catastrophic 2018 Kerala floods, reigniting concerns about the fragile environmental conditions in the Western Ghats.

Unprecedented Rainfall:

In just 24 hours, Wayanad received more than 140 mm of rainfall, far surpassing predictions and triggering widespread landslides. The devastation underscores the urgent need for enhanced disaster management and environmental conservation measures in the region.

• Government Response:
• In light of such recurring disasters, the central government is set to introduce the Disaster Management (Amendment) Bill, 2024, during the 18th Lok Sabha. The Bill aims to establish a comprehensive disaster database at both the national and state levels, alongside the creation of Urban Disaster Management Authorities for state capitals and major cities with Municipal Corporations.

Understanding Landslides

Definition:

• Landslides refer to the downward movement of rock, soil, and debris along a slope. These movements can vary from minor shifts to massive, destructive events. Landslides can occur on both natural and man-made slopes, triggered by various factors such as:
• Natural Causes:Heavy rainfall, earthquakes, volcanic activity, and changes in groundwater levels.
• Human Activities:Construction, deforestation, and other land-use changes.

Types of Landslides:

• Slides:Involve movement along a rupture surface, which can be rotational or translational.
• Flows:Involve a mixture of soil or rock with water, moving fluidly, such as earth flows, debris flows, mudflows, and creep.
• Spreads:Result from the lateral extension and cracking of a mass, often due to liquefaction.
• Topples:Involve forward rotation and free-fall from a steep slope.
• Falls:Involve detachment from a cliff or steep slope, followed by free-fall, bouncing, or rolling.

Landslide Vulnerability in India:

Landslide Atlas of India (ISRO):

• India ranks among the top five landslide-prone countries globally, alongside China, the US, Italy, and Switzerland. Approximately 12.6% of India’s land area (about 0.42 million sq. km) is susceptible to landslide hazards. Reported landslides in India are distributed as follows:
• 5% in the Northwestern Himalayas
• 8% in the Northeastern Himalayas
• 7%in the Western Ghats

Economic Impact:

• According to the Geological Survey of India, landslides can lead to economic losses equivalent to 1-2% of the Gross National Product (GNP) in many developing countries.

Major Landslide-Prone Regions in India:

• Northeastern Region: Accounts for about 50% of the total landslide-prone areas.
• Himalayan States: Uttarakhand, Himachal Pradesh, Jammu & Kashmir.
• Western Ghats: States like Maharashtra, Goa, Karnataka, Kerala, and Tamil Nadu.
• Eastern Ghats: The Araku region in Andhra Pradesh.

Landslide-Prone Areas in Kerala:

• Nearly 17,000 sq. km in Kerala, particularly along the western side of the Western Ghats, is mapped as landslide-prone.

Notable Landslide Events in India:

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

Gravitational Forces:

• Primary Cause:Gravity constantly pulls materials on slopes downward. When gravitational forces exceed the shear strength of geomaterials like rocks, sand, silt, and clay, the slope fails, leading to landslides.

Natural Triggers:

Rainfall:

• Prolonged or intense rainfall increases soil moisture content, reducing cohesion and adding weight to slopes, making them prone to failure.
• In Wayanad, the terrain’s distinctive two-layer structure—a soil layer atop hard rocks—exacerbates the issue. Heavy rainfall saturates the soil, weakening the bond between soil and rocks, triggering landslides.

Earthquakes:

• Earthquakes destabilize slopes by shaking the ground and weakening the structural integrity of geomaterials, particularly in tectonically active regions like the Himalayas.

Erosion:

• Natural processes like river or wave action can erode the base of slopes, undermining their stability. Coastal areas are especially vulnerable due to wave-induced erosion.

Anthropogenic Influences:

Deforestation:

• Deforestation removes vegetation that stabilizes slopes through tree roots, increasing landslide risks.
• Historical deforestation for agriculture and tea plantations by the British in the Western Ghats has significantly weakened soil stability, making the region more prone to landslides during heavy rains.

Construction and Land Use Changes:

• Activities like mining, road construction, and urban development disrupt natural drainage and load distribution, increasing the risk of landslides.
• Infrastructure development, including tourism facilities, resorts, and artificial lakes, has intensified land pressure and disrupted natural drainage, further heightening landslide risks.

Geological Factors:

• Fragile Ecology of Western Ghats:The Western Ghats’ steep slopes and dual-layered terrain make them particularly vulnerable to landslides when rainwater saturates the soil, increasing its weight and reducing slope stability.

Defunct Quarries:

• Quarry Impact:Even after quarries have ceased operations, their presence can contribute to soil destabilization, as vibrations and shockwaves from past activities weaken the geological structure, making the area more susceptible to landslides during heavy rains.

Western Ghats vs. Himalayan Landslides: A Comparative Analysis

Western Ghats:

Causes:

• Concentrated rainfall
• Overburdening of hills
• Mining and quarrying
• Anthropogenic activities like agricultural practices and windmill projects
• Forest fragmentation with dense vegetation on thin soil

Himalayas:

Causes:

• High seismicity due to tectonic movements
• Easily erodible sedimentary rocks
• Young, energetic rivers (e.g., Ganga, Yamuna, Jhelum) with high erodibility
• Heavy rainfall and snowfall
• Anthropogenic factors such as deforestation, jhum cultivation, and road construction

Challenges Posed by Landslides

Loss of Life and Injury:

• Landslides can result in fatalities and severe injuries. The sudden onset of landslides often leaves little time for evacuation.

Displacement of Communities:

• Landslides can force communities to relocate, disrupting social structures and leading to long-term socio-economic challenges.

Damage to Infrastructure:

• Landslides can cause significant damage or destruction to critical infrastructure like roads, bridges, and buildings, leading to economic losses and hindering 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.

The Complexity of Predicting Landslides:

Challenges in Prediction:

Complexity of Geomaterials:

• The subsurface consists of various rocks and particulate materials with differing strengths, making accurate stability assessments challenging.

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 difficult, complicating risk assessments.

Timing Predictions:

• Forecasting when landslides will occur is challenging, 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.

Government Initiatives for Landslide Risk Mitigation:

National Landslide Risk Management Strategy (2019):

• A comprehensive strategy addressing hazard mapping, monitoring, early warning systems, awareness programs, capacity building, policies, and stabilization measures.

Landslide Risk Mitigation Scheme (LRMS):

• A scheme under preparation aimed at providing 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.

Flood Risk Mitigation Scheme (FRMS):

• A forthcoming scheme for developing flood-risk mitigation infrastructure, primarily in northeastern and Himalayan states, covering structural interventions for flood-risk mitigation and non-structural measures such as floodplain zoning and strengthening of embankments.

Project Vigyan:

• A four-year project launched in 2019, spearheaded by the Geological Survey of India (GSI) with the aim of building a database for managing risks related to landslides. It includes the generation of a National Landslide Susceptibility Map at a 1:10,000 scale, contributing to disaster management planning.

Common Alerting Protocol (CAP):

• A standardized data format for alerting authorities to issue public warnings regarding all types of hazards, including landslides. The CAP alert messages are integrated into various dissemination channels like sirens, radio, television, email, SMS, and online platforms.

Conclusion/Way Forward:

• Comprehensive Disaster Management Framework: The landslide tragedy in Wayanad is a stark reminder of the need for a holistic approach to disaster management, particularly in regions prone to natural calamities like landslides. This approach should encompass improved early warning systems, sustainable land-use planning, and heightened community awareness.
• Addressing Human Impact: Human activities, such as deforestation and unregulated construction, significantly contribute to landslide risks. Strict enforcement of environmental regulations and promoting sustainable development practices are crucial for mitigating these risks.
• Adopting Advanced Technologies: The integration of advanced technologies, such as real-time monitoring systems and AI-based predictive models, can enhance landslide prediction accuracy, providing timely warnings to potentially affected areas.
• Focus on Sustainable Development: Balancing development needs with environmental conservation is essential. Infrastructure projects in landslide-prone areas should incorporate risk assessments and mitigation measures to ensure long-term sustainability and safety.
• Community Involvement: Engaging local communities in disaster preparedness and response planning can significantly improve resilience. Educating residents about the risks and emergency procedures can save lives and reduce the impact of landslides.

• International Collaboration: Learning from global best practices and collaborating with international organizations specializing in disaster management can help India develop more robust strategies for landslide risk reduction.

• Strengthening Policy Frameworks: Finally, the implementation of comprehensive policies, such as the proposed amendments to the Disaster Management Act, is vital for building a more resilient nation capable of effectively managing and mitigating the risks associated with landslides and other natural disasters.