Landslides
- A sudden movement of rock, boulders, earth or debris down a slope under the impact of gravity is termed as a landslide.
Causes of landslides
- Natural factors: Heavy rainfall, earthquakes, snow melting, undercutting of slopes due to flooding.
- Anthropogenic factors: Excavation, cutting of hills and trees, overgrazing by cattle, etc.
Factors influencing landslides
- Lithology, geological structures like faults, hill slopes, drainage, geomorphology, land use and land cover, soil texture and depth, and weathering of rocks.
Types
- Based on materials involved: Rock, debris, soil, loose mud.
- Based on movement of material: Fall, topple, slide, rotational slide or translational slide.
- Based on flow of material: Debris flow, Earth flow, Mudflow, Creep.
Landslides in India: Status
- India is among the top five landslide-prone countries globally.
- At least one death per 100 sq km is reported per year due to landslides.
- Excluding snow-covered areas, approximately 12.6% of the country’s geographical land area is prone to landslides.
- Biggest cause of landslides in India: Variability in rainfall patterns.
NDMA Guidelines on Landslides
- Regularly updating the inventory of landslide incidences in the country.
- Landslide hazard zonation mapping in macro and meso scales after consultation with Border Roads Organization, state governments and local communities.
- Pilot projects to be taken up in different regions of the country to carry out detailed studies and monitoring of select landslides to assess their stability status and estimate risk.
- Setting up early warning systems depending on the risk evaluation and cost-benefit ratio.
- Training and capacity-building measures for professionals and organizations working in the field of landslide management.
- New codes & guidelines to be developed for landslide studies and existing ones have to be revised.
- Establishing an autonomous National Center for Landslide Research, Studies and Management.
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