Mains Marathon

Approach :

• Begin with a general definition of landslides and their occurrence in India.
• Compare the underlying causes of landslides in the Himalayas and the Western Ghats.
• Conclude by referencing the NDMA Guidelines.

Introduction:

Landslides are the downward and outward movement of slope-forming materials triggered by gravity. India is highly prone to landslides, especially in the Himalayan region and the Western Ghats. However, despite both being susceptible, the underlying causes of landslides in these two regions differ due to distinct geological, geomorphological, climatic, and anthropogenic factors.

Body

Landslides in the Himalayas

• The Himalayas are the most landslide-prone zone in India, falling under Zone I and II of the NDMA hazard classification.
• The major causes here are:
  • Tectonic Instability: The Himalayas are geologically young and seismically active due to the ongoing collision of the Indian and Eurasian plates. This tectonic movement leads to frequent landslides.
  • Steep Slopes and Fragile Rocks: The region has sharp elevation gradients and consists of fractured and weathered rocks, making slopes inherently unstable.
  • Heavy Rainfall and Glacial Activity: Intense monsoonal rain and rapid snowmelt destabilize slopes. Climate change-induced glacial lake outburst floods (GLOFs) further increase landslide frequency.
  • Anthropogenic Activities: Unscientific road building, hydroelectric projects, and deforestation exacerbate slope failures.

Landslides in the Western Ghats

• The Western Ghats, although older and tectonically stable compared to the Himalayas, experience a different set of triggers:
  • Intense Rainfall: High precipitation during the southwest monsoon, particularly in Kerala and Karnataka, saturates the soil and reduces slope stability.
  • Lateritic and Weathered Soil: The Ghats are composed of lateritic and deeply weathered rocks which, when saturated, become prone to slippage.
  • Anthropogenic Pressure: Land use changes for plantation agriculture (tea, coffee), urbanization, and deforestation have disturbed the natural drainage and slope equilibrium.
  • Topography: Although not as steep as the Himalayas, certain escarpments and valley regions experience localized landslide activity due to terrain modifications.

Conclusion:

While the Himalayas face landslides due to natural and tectonic factors, the Western Ghats are increasingly affected by human-induced causes. Recognizing these differences is key to effective mitigation and sustainable planning. The NDMA Guidelines (2009) call for region-specific measures like Landslide Hazard Zonation (LHZ) mapping, early warning systems, and eco-safe development to manage landslide risks.