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16-January-2025-Special-Article

January 16 @ 7:00 am - 11:30 pm

WAYANAD’S LANDSLIDES

The study published in Nature Natural Hazards (July 2024) addresses the catastrophic landslides in Wayanad, Kerala, emphasizing the need for enhanced disaster management strategies in regions prone to such natural hazards. Wayanad’s landslides were caused by extreme rainfall, combined with fragile ecological conditions. This event highlights the vulnerability of certain areas in India to rapid debris flows and landslides, which necessitate immediate action for better preparedness and mitigation.

Key highlights of study:

 The primary focus of the study was to analyze rapid debris flows and improve disaster management strategies for landslide-prone areas like Wayanad.

  • Objective: The research aimed to better understand the behavior of debris flows during landslides and develop effective strategies to manage disasters in vulnerable regions.
  • Research Methods: The study utilized advanced techniques such as Run-out Modelling and Rapid Mass Movement Simulation (RAMMS) to monitor debris flow paths, speed, pressure, and material accumulation during landslides.
  • Run-out Analysis: A method to evaluate the potential risks of landslides, including debris flows, rockslide avalanches, and failures of artificial fill and mining waste.
  • RAMMS: A tool that helps in evaluating natural hazard processes and assessing protective measures using a simple graphical interface.

Key Findings of the Study:

  1. Debris Accumulation: The research found significant debris accumulation at lower elevations of slopes, creating future hazards downstream.
  2. Vulnerability Mapping: The study stresses the importance of creating detailed vulnerability maps, including debris flow paths, to identify high-risk zones and prevent development in low-lying areas. This can help minimize destruction and loss of life.
  3. Historical Context: The debris flow in 2024 closely resembled previous landslide events in Wayanad, such as the deadly 1984 landslide and a smaller incident in 2019.
  4. Early Warning Systems: A key recommendation of the study was to establish rainfall and soil moisture monitoring stations to set early warning thresholds. These systems would allow for timely alerts and evacuations to protect lives.

About Landslides:

Landslides involve the downward movement of soil, rock, and debris on a slope, triggered by various factors such as heavy rainfall, earthquakes, volcanic activity, human activities, and groundwater changes.

Types of Landslides:

  • Slides: Movement along a rupture surface (rotational or translational).
  • Flows: Soil or rock mixed with water flowing like a fluid (e.g., mudflows, debris flows).
  • Spreads: Lateral cracking and extension of the mass.
  • Topples: Forward rotation and free-fall from a near-vertical slope.
  • Falls: Detachment from a steep slope or cliff.

Landslide-Prone Areas in India:

According to the Landslide Atlas of India, approximately 0.42 million sq. km (12.6% of the land area) is susceptible to landslides, with regions in the Himalayas, Western Ghats, and other hilly areas facing the highest risks.

High-Risk Zones:

  • North-East Himalayas: 0.18 million sq. km.
  • North-West Himalayas: 0.14 million sq. km.
  • Western Ghats and Konkan Hills: 0.09 million sq. km.

Causes of Landslides:

Gravitational Forces: The force of gravity causes soil, rock, and debris to move downhill when they overcome the material’s strength.

Natural Factors:

  • Rainfall: Heavy or prolonged rainfall increases soil moisture, weakens soil cohesion, and adds weight to slopes, increasing the chances of a landslide.
  • Earthquakes: Shaking during earthquakes destabilizes slopes, especially in tectonically active regions like the Himalayas.
  • Hydrological Factors: Water seepage through porous materials increases pore pressure, weakening slopes.

Human-Induced Factors:

  • Deforestation: Removing vegetation weakens the slope by removing roots that help bind the soil and absorb water.
  • Construction Activities: Mining, road construction, and urban development disrupt natural drainage, increasing landslide risks.
  • Geological Factors: The material composition and structure of rocks, soil, and weathering processes also influence the stability of slopes.

Differences Between Landslides in the Himalayas and Western Ghats:

Himalayas:

Steep, high-altitude, and tectonically active terrain.

  • Earthquakes and heavy monsoon rainfall, along with rapid snowmelt, contribute to frequent landslides.
  • Deforestation worsens soil instability.

Western Ghats:

  • Less steep slopes and lower tectonic activity compared to the Himalayas.
  • Monsoon rainfall leads to soil saturation, but the absence of snowmelt reduces risks.
  • Slight deforestation is still a concern.

Impacts of Landslides:

  • Human Life and Safety: Landslides, especially fast-moving ones, can cause loss of life and injury. Even slow-moving landslides can cause significant property damage over time.
  • Infrastructure Damage: Roads, railways, pipelines, and communication lines may be blocked or destroyed, disrupting essential services.
  • Cascading Effects: Landslides can block streams, creating debris dams that, when they burst, lead to downstream flooding.
  • Economic Loss: Repairing infrastructure, providing humanitarian aid, and restoring disrupted sectors like agriculture and tourism can be costly.
  • Environmental Damage: Landslides degrade ecosystems, leading to soil erosion, habitat loss, and the destruction of vegetation.

Government Initiatives in India:

  1. National Landslide Risk Management Strategy (2019): A comprehensive approach including hazard mapping, monitoring, and early warning systems.
  2. Landslide Risk Mitigation Scheme (LRMS): Focuses on financial support for mitigation in vulnerable states.
  3. Flood Risk Mitigation Scheme (FRMS): Pilot projects for multi-purpose shelters and flood warning systems.
  4. Landslide Atlas of India: Created by NRSC under ISRO, this atlas records landslide events and provides valuable insights for disaster planning.

Measures to Prevent Landslide Hazards:

Engineering Solutions:

  • Slope Stabilization: Use of retaining walls, rock bolts, and soil nails to secure slopes.
  • Grading and Terracing: Modifying slope angles and creating level surfaces.
  • Drainage Systems: Installing systems to control water flow and maintain slope stability.

Natural Solutions:

  • Vegetation Control: Planting vegetation to bind soil, reduce erosion, and absorb excess water.
  • Water Management: Using techniques like contouring to reduce water runoff.
  • Early Warning Systems: Monitoring rainfall and soil stability using technologies like LiDAR and satellite imagery.

Conclusion:

The Wayanad landslides in Kerala serve as a reminder of the urgent need for improved disaster management strategies in vulnerable areas. Engineering solutions, natural approaches, early warning systems, and proper land-use planning are essential to minimize landslide risks and safeguard communities against climate change-driven rainfall extremes.

Mains Question:

  1. Discuss the key factors contributing to landslides in India, with a focus on the differences between the Himalayan and Western Ghats regions. Suggest measures to mitigate their impact. (250 WORDS)

Details

Date:
January 16
Time:
7:00 am - 11:30 pm
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