Landslides

IN NEWS:

• Recently, heavy monsoon rains have triggered landslides in India’s Himalayan region, causing widespread destruction and the loss of human lives in the northern Himalayan states of Himachal Pradesh and Uttarakhand.

WHAT ARE LANDSLIDES:

• The term “landslide” denotes the downward and outward movement of materials including rock, earth or debris down a slope due to gravitational force.
• Avalanche is the down slope movement of large detached mass of snow and ice along with rock fragments, soil and vegetation.
• They are disasters of Hydrogeological origin, which result in the failure of the materials which fall down the slope due to force of gravity.

INDIA’S VULNERABILITY:

• Landslides affect at least 12.6 per cent of the land area of our country—an area which exceeds 0.42 million km². The phenomenon is pronounced during the monsoon period.
• Landslides of different types are frequent in geodynamically active domains in the Himalayan and Arakan-Yoma belt of the North-Eastern parts as well as in the relatively stable domains of the Meghalaya Plateau, Western Ghats and Nilgiri Hills.
• The two regions most vulnerable to landslides are the Himalayas and the Western Ghats.
• The Himalayan mountain belt is comprised of tectonically unstable younger geological formations subjected to severe seismic activity. The Western Ghats and Nilgiris are geologically stable but have uplifted plateau margins influenced by neo-tectonic activity.
• Compared to the Western Ghats region, the slides in the Himalayas region are huge and massive, and in most cases, the overburden along with the underlying lithology is displaced during sliding, particularly due to the seismic factor.
• Sporadic occurrences of landslides have been reported in the Eastern Ghats, Ranchi Plateau, and Vindhyan Plateau as well.
• The Geological Survey of India (GSI) is the nodal agency for landslide management.

WHAT MAKES INDIA VULNERABLE:

• Young geology:
  • Himalayas are mostly composed of highly unconsolidated sedimentary rocks, which get easily disturbed under stress.
• Swift rivers:
  • The numerous rapid flowing streams in the Himalayan and Western ghats region erodes and undercuts hills, creating steep banks which aid in rapid movement of materials.
• Tectonic activities:
  • Himalayas lie at the convergence zone of the Indian and Eurasian tectonic plates. Hence, the range is geologically very active, resulting in the formation steep slopes, fragile rock structure and rugged topography.
• Heavy rainfall:
  • Water or snowfall can trigger landslides as it alters the pressure within the slope, which leads to slope instability. Also, it can lead to the rise in groundwater levels and formation of water saturated particles. The Himalayas and the Western ghats are among the areas that receive short-period, high-intensity rainfall and hence landslides are frequent here.
• Anthropogenic activities:
  • Deforestation, highway and building excavations, mine-waste piles, open-pit mines and quarries and shifting cultivation result in the region alters the slope and leads to landslides. Also, hydraulic constructions such as Multipurpose dams alters the groundwater levels, thereby aiding landslides.
• Forest fires:
  • Severe wildfires damage the forest canopy, the plants, as well as the soil. The loss of deep-rooted vegetation creates loose soil. These factors can result in increased runoff after intense rainfall or rapid snowmelt, which increases chances of landslides.

NDMA GUIDELINES ON LANDSLIDE MANAGEMENT:

• The National Disaster Management Guidelines for Management of Landslides and Snow Avalanches include a wide range of scientific, planning, and administrative tools to address various aspects of these hazards to effectively reduce losses from them.

• It includes nine major elements to enhance the effectiveness of managing landslides in the country:
  1. Vulnerability and Risk Assessment: delineating areas susceptible to landslide hazards and conducting site specific studies of landslides and preparation of landslide inventory.
  2. Multi-Hazard Conceptualization: Integrating landslide concerns into multi-hazard disaster management plans at different levels for effective risk assessment, mitigation and response
  3. Landslide Remediation Practice: Encouraging implementation of successful landslide remediation and mitigation technologies, and execution of pace setter examples in mitigation and remediation strategies to build confidence amongst the affected communities.
  4. Research and Development; Monitoring and Early Warning: Establishment of an autonomous national centre for landslide research, studies and management. Enhancing landslide education, training of professionals and capacity development of organisations working in the field of landslide management.
  5. Knowledge Network and Management: Establishing an effective system for gathering information on landslides, loss assessment and effective dissemination of technical information and maps.
  6. Capacity Building and Training: Developing institutional capacity and training for geoscientists, engineers, and planners is necessary for effective management of the landslide hazard. Development of new codes and guidelines on landslide studies and revision of existing ones.
  7. Public Awareness and Education: Effective communication of landslide hazard issues to the affected communities through education, public awareness programmes, posters, audio-visual aids, media campaigns, etc.
  8. Emergency Preparedness and Response: Development of coordinated landslide rapid response capability involving scientists, engineers, local authorities, the National Disaster Response Force and paramilitary forces.
  9. Regulation and Enforcement: Establishment of a techno-legal mechanism of landslide hazard assessment and mitigation with provisions for enforcing compliance.

OTHER MEASURES TAKEN:

• National Landslide Risk Management Strategy:
  • It is a strategy document by the NDMA to strengthen and mainstream landslide management. Its key aspects include:
    • Preparation of Landslide Hazard Zonation maps
    • Developing and implementing Landslide Monitoring and Early Warning System
    • Participatory approach in awareness generation and preparedness
    • Management and Inclusion of new technology inputs for capacity building and training programs
    • Preparation of Mountain Zone Regulations and Policies
    • Stabilization and Mitigation of Landslide and Creation of Special Purpose Vehicle (SPV) for Landslide Management
• Landslide Atlas of India:
  • The National Remote Sensing Centre (NRSC) under ISRO has released the Landslide Atlas of India in 2023.
  • It is a detailed guide identifying landslide hotspots in the country.
  • For the first time, scientists did a risk assessment on the basis of 80,000 landslides recorded between 1998 and 2022 in 147 districts in 17 states and two Union Territories to build a "Landslide Atlas" of the country.
  • The atlas used satellite data of ISRO to map all seasonal and event-based landslides, like the Kedarnath disaster in 2013 and landslides triggered due to the Sikkim earthquake in 2011.
  • Extra reading: https://ilearncana.com/details/Landslide-Atlas-of-India/4185
• National Landslide Susceptibility Mapping (NLSM) programme:
  • Geological Survey of India has launched a national programme on landslide susceptibility mapping with an aim to cover the 0.42 million sq. km landslide prone areas of the country. This national programme was formally launched in 2014.

CHALLENGES TO LANDSLIDE MITIGATION & MANAGEMENT:

• Ad hoc strategies:
  • Landslide management measures are generally planned on an ad hoc basis to give immediate relief to affected people. The strategies focus on post disaster relief measures than on pre-disaster risk reduction planning.
• Outdated maps:
  • Majority of the existing Land Zonation Maps (LSZ) lack micro levels details of slopes and landslide events of the past. Also, State-wise and district-wise landslide zonation maps are mostly not available for landslide prone areas.
• Weak forecasting:
  • In Indian Himalayas, the poor network of weather stations and lack of high elevation rain gauges mars the collection of useful data that can help establishing meaningful predictions. Climate change induced variations is worsening this situation.  
• Poor law enforcement:
  • While laws and regulations are in place to regulate human activities in landslide-prone areas, their enforcement remains an issue. This is evident from the presence of rampant construction, illegal mining and deforestation activities along the sensitive Himalayan and western ghats region.
• Lack of Public awareness:
  • The main cause of losses during landslides is the lack of awareness among the people regarding the potential landslide zones and mitigation strategies, as awareness programmes are not reaching the communities.
• Population pressure:
  • The demand for land in India is severe due to its rising population. Also, hilly areas have economic significance in the form of plantations, timber and construction material. Hence, it is difficult to completely prohibit land use in the areas or enforce stringent environment laws.

WAY FORWARD:

• Preparedness-centric approach:
  • Landslide management is yet to be seen as an essential part of good governance and integral to development planning in India. The strategies must focus on integrated pre-disaster preparation and disaster risk mitigation strategies.
• Research and development:
  • An autonomous national center for landslide research, studies and management has to be established. A strategy has to be developed by NDMA to make available micro and meso level zonation maps and a landslide database for better management of landslides.
• Budgetary allocation:
  • State Governments of landslide prone states can make provision for landslide management head in the budget allocation of Public Works Department, Irrigation Department, Rural Engineering Services and Department of Disaster Management.
• Forecasting & Early Warning Systems:
  • India must improve its forecasting capability to through better upkeeping of existing systems and investment into new systems. Also, IT based tools must be leveraged for the dissemination of real time data and flood warnings.
• Develop techno-legal regime:
  • The regulation of developmental activities in landslide prone areas through an appropriate techno-legal regime is an urgent necessity. This can be in the form of specific land use policies, land zoning regulations in hilly areas, developing socio-economic profile of the communities residing in these areas etc.
• Community participation:
  • Local communities and NGOs should be involved in awareness generation and capacity building programmes. For this, Community Education Programme of 10 to 15 days may be initiated by the governmental agencies in vulnerable areas.
• International cooperation:
  • State governments and NDMA should interact at the international level to share best practices and get exposed to the latest development in the domain of landslides management.

PRACTICE QUESTION:

Q. Discuss the vulnerability of India to landslides. Also, explain the issues associated with landslide mitigation and prevention in the country and suggest solutions.