Note4Students

From UPSC perspective, the following things are important :

Prelims level: Landslide Atlas of Indi

Mains level: Heavt rain induced disasters

landslide

The Indian Space Research Organisation (ISRO) recently released the Landslide Atlas of India to identify landslide hotspots in the country.

What are Landslides?

Landslides are natural disasters that occur in mountainous terrains where soil, rock, geology, and slope conditions are conducive.
A landslide is the sudden movement of rock, boulders, earth, or debris down a slope.
They can be triggered by natural causes such as heavy rainfall, earthquakes, snowmelting, and undercutting of slopes due to flooding.
They are extremely hazardous, posing a threat to human and animal lives, damaging property, roads, and bridges, disrupting communication lines, and snapping power lines.
Landslides are broadly classified based on the type of materials involved, the type of movement of the material, and the type of flow of the material.

Why do they occur?

Landslides are natural disasters that occur mainly in mountainous terrains due to conducive conditions of soil, rock, geology, and slope.
Heavy rainfall, earthquakes, snow-melting, and undercutting of slopes due to flooding can trigger landslides.
Anthropogenic activities such as excavation, cutting of hills and trees, excessive infrastructure development, and overgrazing by cattle can also cause landslides.

Factors contributing

The main factors that influence landslides include lithology, geological structures like faults, hill slopes, drainage, geomorphology, land use and land cover, soil texture and depth, and weathering of rocks.
Rainfall variability pattern is the single biggest cause for landslides in India, with the Himalayas and the Western Ghats remaining highly vulnerable.

India is considered among the top five landslide-prone countries globally, where at least one death per 100 sq. km is reported in a year due to a landslide event.
Approximately 12.6% of the country’s geographical land area (0.42 million sq km) is prone to landslides, with 66.5% of landslides reported from the North-western Himalayas, 18.8% from the North-eastern Himalayas, and 14.7% from the Western Ghats.

Mizoram recorded the highest number of landslide events in the past 25 years, with 12,385 events, of which 8,926 were recorded in 2017 alone.
Nagaland and Manipur also reported a high number of landslide events during the 2017 monsoon season.
Uttarakhand and Kerala reported the highest number of landslides, with Uttarakhand experiencing 11,219 events since 1998, and Kerala making inhabitants significantly vulnerable to fatalities, despite fewer events.

Landslides are broadly classified based on the type of materials involved, type of movement, type of flow of the material, and whether they spread laterally.
The Landslide Atlas of India maps landslides mainly based on events and seasons.
The National Remote Sensing Centre (NRSC) used a landslide database created from 1998 to 2022 using aerial and high-resolution satellite images.