INDIAN LANDSLIDE SUSCEPTIBILITY MAP

Why in the News?

IIT Delhi created the first hi-resolution Indian Landslide Susceptibility Map (ILSM)

About Indian Landslide Susceptibility Map (ILSM) 

    • A landslide susceptibility map divides the terrain into zones based on the likelihood of landslide occurrence. 
  • Key Feature of ILSM:
    • It uses Innovative Framework (big data and use of multiple machine learning models) for High-Resolution Landslide Mapping. 
    • The map model incorporates 16 landslide conditioning factors such as height, slope, soil composition, road distance, river proximity, vegetation cover, precipitation, etc. 
    • Map has a spatial resolution of 100 metres with over 95% accuracy. 
    • Map divides India into Five Vulnerability Classes. 

Key Findings of ILSM:

    • Overall Landscape Susceptibility to Landslides in India: Map classifies 13.17% of India’s geographical area as susceptible to landslides. 
      • 4.75% of the area is categorized as “very highly susceptible.” 
      • Geological Survey of India estimates a slightly lower figure at 12.6%. 
  • Regional Variation in Susceptibility: 
    • Sikkim has the highest percentage of land area (57.6 %) susceptible to landslides. 
    • Arunachal Pradesh has the highest absolute area susceptible to landslides. 
    • Kerala, among the non-Himalayan regions, exhibits the highest area susceptible to landslides. 
  • Identification of New Landslide-Prone Zones: Eastern Ghats show landslide-prone zones identified by the map. 
    • These zones were not reported by previous models or government records. 
About Landslide

  • Landslides occur when gravity forces pushing on hill slope material exceed the frictional forces holding the material in place, causing slope failure. 
  • Due to steep slopes and heavy rainfall most of the landslides occur in the northwest Himalayas followed by the northeast Himalayas and the Western Ghats. 
  • The Himalayas are composed of sedimentary rocks which are prone to denudation and erosion. So, Steep slopes and rapid rivers contribute to toe erosion making the slope unstable. Most of the landslides in the Himalayas are rockfalls.
  • The presence of basalt rocks and gentle-sloped rivers in the Western Ghats resulted in fewer rockfalls. However, weathering due to heavy rainfall has led to the development of a thick layer of regolith, thereby leading to mudslides.
  •  Road development and construction contribute to slope instability which can also lead to landslides.

Initiatives Taken by India:

  • National Landslide Risk Management Strategy: Released by National Disaster Management Authority (NDMA).
  • National Landslide Susceptibility Mapping (NLSM) Programme: Launched in 2014-15, under it Geological Survey of India has completed landslide susceptibility mapping.
  • Landslide Atlas of India: The database, prepared by National Remote Sensing Centre (NRSC) of ISRO, covers landslide-vulnerable regions in 17 states and 2 UTs of India in the Himalayas and Western Ghats.
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