Rudraprayag and Tehri Gharwal in the Himalayan state of Uttarakhand have been the most landslide-hit districts in the last two decades, suggests satellite data captured by the Indian Space Research Organization (ISRO). This region not only has the highest concentration of landslides, but also the highest exposure due to population.
The findings emerged from the latest risk assessment done by scientists at the Hyderabad-based National Remote Sensing Center who compiled an all-India database of nearly 80,000 landslides that occurred from 1998 to 2022. All seasonal and event-based landslides such as the Kedarnath disaster in 2013 and the Sikkim earthquake in 2011 triggered landslides.
147 affected districts
The team used this data to rank 147 landslide-prone areas across 17 states and two union territories in terms of key socio-economic parameters for their landslide exposure. According to scientists, the risk has intensified over the years due to environmental degradation and extreme weather events due to climate change.
Although a large part of the Himalayan region is susceptible to landslides, it is the high population density, major pilgrimage routes and tourist spots that worsened the impact of the disaster in Jammu and Kashmir, Himachal Pradesh and Uttarakhand. 64 districts in the northeast also figure in the list, apart from southern states like Kerala that have witnessed fewer landslides but have faced major devastation due to population density.
Thrissur (Kerala), Rajouri (Jammu and Kashmir), Palakkad (Kerala), Poonch (J&K), Malappuram (Kerala), South and East districts of Sikkim and Kozhikode (Kerala) were listed among the 10 worst affected districts. Two districts of Uttarakhand. It is the first time a pan-India database of rainfall-induced landslides has been prepared, the agency said.
India is prone to landslides
Excluding snow covered areas, India is among the top four countries with more than 12.6 percent of land at risk of landslides. It covers the Himalayas, Western Ghats, Konkan Hills and Eastern Ghats of Peninsular India which are highly susceptible to mass movement due to mountainous topography and heavy rainfall events, which have increased due to climate change.
In India, such disasters mostly occur during the monsoon season. Scientists say they can now detect slow-moving mountain slopes thanks to time-series measurements from space using microwave satellite data and the INSER technique, which can detect displacements at the millimeter level.
However, predicting the flow path of those landslides and identifying the release area that might be affected still remains a daunting challenge.
Satellite and meteorological data are being used to provide regional early warning for selected routes in Himachal Pradesh, Uttarakhand and northeastern states during monsoon. These are based on the rainfall threshold for landslides, which is the amount of rain that can cause landslides in the area.
NRSC developed a mobile app — FLIM — to collect landslide data from the field to develop a landslide warning system. Data collected by the app is uploaded to BHUVAN and NDEM servers for analysis and visualization and alerts accordingly.
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