India is among the top four countries with the highest landslide risk
In India, most of the landslides occur in the monsoon months (between June and September). Rainfall is a major trigger. The combined effect of water with the landscape's shape, geology, soil, and vegetation can cause landslides.
India accounts for 16% of rainfall-triggered landslide events worldwide.
Landslides are a frequent geological hazard in hilly areas, and in India, 12.6% of the land is prone to landslides.
Landslides can also occur due to human activities like construction, mining, and overgrazing.The Himalayas and Western Ghats are most at risk due to their hilly terrain and heavy rainfall.
The northern states are greatly affected. The states of Jammu & Kashmir, Himachal Pradesh, and Uttarakhand are the worst affected by landslides because most of their area is in the Himalayas.
Even with fewer landslides than in the Himalayas, the Western Ghats are more vulnerable due to higher population densities.
ISRO supports disaster management. Since 2005, the National Remote Sensing Centre (NRSC) has provided satellite-based support for landslide disasters as part of ISRO’s Disaster Management Support (DMS) programme.
Satellite data aids landslide study as it can reach remote, inaccessible mountains.
Mapping landslides. NRSC has created a landslide hazard zonation (LHZ) map on a 1:25,000 scale for the first time in India in 2001 using GIS and AHP techniques.
NRSC has a large database of landslides covering landslide vulnerable regions in 17 states and 02 UTs of India in the Himalayas and Western Ghats through its Landslide Atlas of India [PDF, 2023].
NRSC has created a database of approximately 80,000 landslides that occurred over the last two decades [1998-2022] using satellite data. This data helps understand the geology and rainfall patterns that cause landslides and determine which districts are most exposed.
Mizoram, Uttarakhand, and Tripura have the highest number of landslides recorded in the inventory.
Although the North Eastern states have many landslides yearly, they are not particularly vulnerable to them in terms of socioeconomic factors due to their lower population density and wide unoccupied mountain areas.
The Atlas shows that the Northwest Himalayas contribute the most (66.5%) of landslides in India.
Landslides are classified based on the type of movement and the materials involved. Types of movement include falls, topples, slides, spreads, and flows. Materials can be rock, debris, earth, soil, or mud.
Geomorphological changes led to the disastrous landslides in Kedarnath, Uttarakhand during 16-17 June 2013. Heavy rainfall caused flash floods and the reactivation of an old landslide, which damaged a river training wall and resulted in the flooding of Kedarnath town. The flooding not only buried the town with debris but also changed the course of the Mandakini River from west of Kedarnath town to east of it.
On August 20, 2024, a massive landslide took place in Balutar, Sikkim which substantially damaged the Teesta V, a 510 MW hydel power station. There were several landslide incidents in Sikkim in 2024 due to heavy rainfall.
Predicting when a landslide will occur is possible using satellite data (InSAR technique) which can detect ground movement at millimetre level.
The FLIM mobile app developed by NRSC/ISRO is used to collect landslide data from the field and help develop a landslide warning system for the landslide-prone regions.