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Landslide Atlas of India 2023

Context: Recently, the Indian Space Research Organisation (ISRO) has released the Landslide Atlas of India.

About the Landslide Atlas of India 2023

  • This report looked at landslide vulnerable regions in 17 states and two Union Territories of India in the Himalayas and Western Ghats.
  • Hyderabad-based National Remote Sensing Centre (NRSC) created the all-India database of nearly 80,000 landslides that occurred from 1998 to 2022.
    • NRSC, is one of the primary centres of the ISRO, responsible for remote sensing satellite data acquisition and processing for disaster management purposes.
  • The risk analysis in the report was based on the density of human and livestock populations, which indicates the impacts on people due to these landslides.

Important Highlights from the ‘Landslide Atlas of India’

  • India’s vulnerability to landslides: India is among the top four countries with highest landslide risk, where for every year the estimated loss of life per 100 km2 is greater than one.
    • Approximately 0.42 million sq. km or 12.6% of land area of India, excluding snow covered area, is prone to landslide hazard.
    • In India, landslides mostly occur in the monsoon season. Himalayas and Western Ghats are highly susceptible to mass movements due to hilly topography and heavy rainfall.
  • Most vulnerable districts: Rudraprayag and Tehri Garhwal in Uttarakhand are the most landslide-prone districts in the country.
    • Rajouri, Thrissur, Pulwama, Palakkad, Malappuram, South Sikkim, East Sikkim and Kozhikode in Kerala, Jammu Kashmir and Sikkim are other high-risk districts, found the Atlas.
  • Maximum landslides: Between 1988 and 2022, the maximum number of landslides — 12,385 — were recorded in Mizoram.
    • Uttarakhand followed it at 11,219, Tripura at 8,070, Arunachal Pradesh at 7,689, Jammu and Kashmir at 7,280.
  • Causes of landslides:
    • Rainfall variability: The majority of landslides are triggered by variability in rainfall patterns.
    • Climate change: Sudden heavy rains due to climate change are also increasing landslides, said the report.
    • Himalayan region: Around 73 per cent of landslides in the Himalayan region are attributed to heavy rains and reduced water-absorbing capacity of the soil.
  • Vulnerability of the Himalayas and the Western Ghats
The Himalayas The Western Ghats
The spatial distribution of landslides in the Himalayas is controlled by the shale-sandstone-meta sediments generating dissected hills and valleys over the Himalayan range with slopes 30° to 45°.

This, together with rainfall between 750-1000 mm is the cause of landslides.

Also, the Chenab sub-basin, whose geographic expanse primarily comprises steeply sloping mountains, records the highest number of landslides

The vulnerability of the inhabitants and households is more significant in the Western Ghats due to the very high population and household density, especially in Kerala, even when fewer landslides exist than in the Himalayan regions.

The steep escarpments of the Western Ghats record occurrences of landslides, but however, these are primarily controlled by the soil cover on the slopes.

About Landslides

  • The definition of landslide is “a movement of mass of rock, earth or debris down a slope”.
  • Causes: They can be triggered by rainfall, undercutting of slopes due to flooding or excavation, earthquakes, snowmelt and other natural causes, as well as anthropogenic causes such as over grazing by cattle, terrain cutting and filling, excessive development, etc.
  • The occurrence of landslides in an area is due to the interplay of favourable terrain parameters such as slope, lithology, topography and land use which trigger landslides in response to rainfall or earthquake events.
  • As per the United Nations International Strategy for Disaster Reduction (UN/ISDR), landslide ranked 3rd in terms of number of deaths among the top ten natural disasters.
  • Landslide classification: The term landslide encompasses five modes of slope movement i.e., falls, topples, slides, spreads, and flows.
    • Falls: Falls are rapid movements of rocks and boulders detached from steep slopes or cliffs along fractures, joints, and bedding planes.
    • Topple: It is the forward rotation of a mass of debris or rock out of a slope. The slope failure generally occurs at point near the base of the block of rock.
    • Slides: A slide is a downslope movement of material that occurs along a slip surface.
    • Lateral Spreads: It is the lateral movement usually occur on very gentle slopes or flat terrain. The failure is caused by liquefaction due to earthquake.
    • Flow: It refers to the movement of soil, rock, or other debris down a slope in a fluid-like manner.

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What is Landslide Atlas of India 2023 Report?

This report looked at landslide vulnerable regions in 17 states and two Union Territories of India in the Himalayas and Western Ghats.

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