The Border Roads Organisation (BRO) clears the rubble that accumulated on the highway at Hanuman Chatti in Uttarakhand after a landslide. (File pic/PTI)
The Geological Survey of India is currently in the process of conducting site-specific studies for over 100 most-affected areas, analysing their geology and determining the terrain-specific rainfall threshold that could trigger landslides
With an increase in heavy rainfall events triggering landslides across several states, the Geological Survey of India (GSI) has now picked up the pace to install an early warning system for such incidents in the most-affected districts.
The nodal agency has already completed landslide susceptibility mapping for the states and collected the baseline data.
In an exclusive interview with News18, GSI deputy director general Asit Saha said the target is now to complete the site-specific studies in over 100 such most-affected areas across the country as early as possible.
“It is quite a time-intensive process, but we already have our specialised teams on the ground. They have been conducting the geological mapping, analysis of slope stability to determine all kinds of factors that cause such disasters,” said Saha. “But, the key element is also to determine the terrain-specific rainfall threshold which may trigger these landslides. This value is different for each region. All that information would be fed into our models to generate timely early warnings. We hope to get the system operational in another two years’ time.”
The GSI is working in collaboration with India Meteorological Department (IMD) and other specialised centres to integrate the required weather data into the system. The years-long nationwide project is likely to be completed in another two years.
TWO PILOT AREAS
As the nodal agency for landslides, GSI has already instituted early warnings for Darjeeling in West Bengal and the Nilgiris district in Tamil Nadu on a pilot basis. Both districts receive daily forecast bulletins during the monsoon season as part of the Landslide Early Early Warning System (LEWS), which is currently being tested and evaluated.
“The nature of landslides is different from one region to another. They may be seasonal or event-based, so we have to consider all geological, topographical, and hydrological factors. We also suggest mitigation measures that may be taken to reduce the loss of life and property in such disasters in the future,” said Saha. A similar study has been completed for Kinnaur in Himachal Pradesh in collaboration with the state government.
The GSI had also recently integrated the Landslide Susceptibility Module into Flash Flood Guidance System to improve the predictability of landslide-associated flash floods in vulnerable hilly regions. The system is now operational in the Rudraprayag district of Uttarakhand and Wayanad district of Kerala.
INDIA’S HIGH VULNERABILITY TO LANDSLIDES
A major hydro-geological hazard, landslides are invariably triggered due to incessant rains, but they have been worsened by human activities – mining and rampant construction on the hills which have weakened the topography of these areas.
As per IMD data (citing media reports), over 660 lives were lost due to heavy rain events that triggered floods and landslides in different parts of the country in 2022. Of these, Assam was most affected with over 198 deaths, 73 in Maharashtra, 61 in Himachal Pradesh, 56 in Manipur (due to the massive landslide in Noney district in June), and 47 in Rajasthan.
In fact, India is among the top four countries that have the highest landslide risk, with over 12.6 per cent of the land area (excluding snow-covered parts) prone to the hazard. This includes the Himalayas, Western Ghats, Konkan Hills, and Eastern Ghats of peninsular India which are highly susceptible to mass movements due to hilly topography.
The latest risk assessment done by scientists from Hyderabad-based National Remote Sensing Centre using satellite data from 1988 to 2022 showed how Rudraprayag and Tehri Garhwal in Uttarakhand have become the most landslide-affected districts over the past two decades. The region not only has the maximum density of landslides but also the highest exposure due to population.
With extreme weather events increasing in intensity and frequency globally due to climate change, the World Meteorological Organisation (WMO) has also implored all countries to put into place life-saving early warning systems for all hazardous weather events by the end of 2027. According to the Global Commission on Adaptation, giving just 24 hours’ notice of an impending hazardous event can reduce damage by 30 per cent.
