Landslides

Mains Marks Booster     5th August 2023        
Samadhaan

Landslide, also called landslip, is the movement of a mass of rock, debris, earth, or soil (soil being a mixture of earth and debris). Landslides occur when gravitational and other types of shear stresses within a slope exceed the shear strength (resistance to shearing) of the materials that form the slope.


LANDSLIDES AND INDIA 

  • Landslides and avalanches are among the major hydro-geological hazards that affect large parts of India  
  • The Himalayas, the Northeastern hill ranges, the Western Ghats, the Nilgiris, the Eastern Ghats and the Vindhyans, in that order, cover about 15 % of the landmass.
  • Economic loss -1-2% of the gross national product
  • Human loss- Between 1998-2017, landslides affected an estimated 4.8 million people and cause more than 18 000 deaths. 
  • Landslides across the south Asian country of India led to 295 deaths in 2020

Causes of Landslide:

Causes of Landslide

Hazard Zonation Mapping As A Critical Tool For Landslide Disaster Mitigation:

  • Identification of Risk Areas: The primary objective of hazard zonation mapping is to identify and categorize regions based on their potential risk to landslides. This helps to prioritize areas needing immediate mitigation measures and to establish early warning systems.
  • Planning and Development: It guides planners, developers, and policymakers in making informed decisions about land use, zoning laws, building codes, and urban planning by providing a visual representation of areas susceptible to landslides.
  • Infrastructure and Construction Design: The information obtained from hazard zonation mapping can help in designing infrastructure and buildings that can withstand the impacts of landslides. Engineers can incorporate these data into the design and construction of roads, bridges, and other critical infrastructure.
  • Emergency Preparedness and Response: Zonation mapping can facilitate the planning of evacuation routes and emergency response strategies, ensuring that they are effective and efficient during a landslide event.
  • Insurance and Investment Decisions: Insurance companies can use this information to determine risk and set premiums for property insurance. Similarly, investors and homeowners can make informed decisions about where to invest or purchase property.
  • Education and Awareness: Hazard zonation maps can also be used to increase public awareness about landslide risks, helping communities to understand and prepare for potential landslide events.
  • Environmental Protection: These maps can help identify areas where deforestation, excessive groundwater extraction, or other human activities might increase landslide risks, thereby informing policies to protect these areas.
  • Long-Term Monitoring and Research: Hazard zonation mapping can assist in long-term monitoring of landslide-prone areas and provide valuable data for further research into landslide patterns and mitigation strategies.

National Landslide Risk Management Strategy of India by NDMA:

  • Landslide Hazard Zonation: The strategy emphasizes the need to strengthen and validate landslide zoning maps. It proposes using advanced tools such as Unmanned Aerial Vehicles (UAVs), Terrestrial Laser Scanners, and high-resolution Earth Observation data. The document suggests creating maps at macro (1:50,000 / 25,000) and meso (1:10,000) scales and implementing monitoring and quality-checking mechanisms.
  • Landslide Monitoring and Early Warning System: The document highlights previous work, identifies gaps, and suggests future prospects, including the development of rainfall thresholds, Numerical Weather Prediction (NWP), Automatic Rain Gauges, Wireless Sensor Networks (WSN), and Micro-Electro-Mechanical Sensors (MEMS).
  • Awareness Programmes: The strategy underscores the importance of raising awareness and preparedness through community engagement. The objective is to help communities take preventive measures and respond effectively in case of an emergency.
  • Capacity Building and Training: The document recommends conducting a nationwide Training Need Assessment (TNA) in Landslide Risk Management, including new technology for capacity building and training programs. It emphasizes the need to strengthen the response framework at the grassroots level.
  • Mountain Zone Regulations and Policies: The strategy suggests formulating land-use policies and a techno-legal regime, updating and enforcing building regulations, reviewing and revising BIS codes/guidelines for landslide management, and amending town and country planning legislations for natural hazard-prone areas.
  • Stabilization and Mitigation of Landslides: The document details the need for specific land-use policies, enforcement of building regulations, and proposed amendments in town and country planning legislations in landslide-prone areas.
  • Creation of Special Purpose Vehicle (SPV) for Landslide Management: The strategy mentions efforts made by the Task Force, including pilot projects for landslide hazard zonation maps, low-cost landslide monitoring solutions, training and capacity building initiatives, and the proposed creation of a "Centre for Landslide Research Studies and Management".

The strategy aims to mainstream landslide disaster risk reduction (DRR) in disaster management activities, providing guidance for States/UTs, Ministries/Departments, and other stakeholders in their developmental projects, and serving as a guidebook for SDMAs/DDMAs in their disaster risk management initiatives.

Government initiative

  • In India, the Ministry of Environment, Forest and Climate Change (MoEFCC) is responsible for landslide management. 
  • National Landslide Susceptibility Mapping (NLSM) project to identify landslide-prone areas in the country. 
  • The Geological Survey of India (GSI) and the Central Water Commission (CWC) are also involved in landslide management in India.
  • NDMA guidelines on landslide disaster management.
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