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India has rolled out its first regional early warning system for rain-induced landslides, just two weeks before the devastating Wayanad tragedy claimed around 350 lives.
The National Landslide Forecasting Centre (NLFC), inaugurated on July 19, 2024, by Union Minister G Kishan Reddy, is the brainchild of the Geological Survey of India (GSI). Residents of Kalimpong, Darjeeling and Nilgiris were the initial beneficiaries of live landslide forecasts. The government aims to expand this network to other landslide-prone regions by 2030, Reddy added.
Four days later, daily forecast bulletins for the three regions went live.
The NLFC is also experimenting with forecast bulletins for 13 other landslide-prone areas in Himachal Pradesh, Uttarakhand, Sikkim, West Bengal, Tamil Nadu and Kerala for the state and district disaster management authorities.
However, these bulletins are currently restricted. “These experimental forecast bulletins are not to be shared with the public by anybody,” Saibal Ghosh, deputy director general, GSI, told Down To Earth (DTE). The nodal agency is still fine-tuning its forecast models using input and feedback from disaster management authorities.
An early warning system (EWS) comprises a device, system or set of capacities that generate and share timely and meaningful information to allow individuals, communities, and organisations to act in time to avoid or reduce the impact. It consists of four components: Risk knowledge, monitoring and warning, dissemination and communication, and response capability.
These systems are intended to forecast landslides or quantify the likelihood of one occurring in a specific area at a given time.
The early warning systems can be regional, covering a large municipality, a metropolitan area, an administrative district, a province, or a region. It can also be slope-specific, focussing on a particularly vulnerable hill slope. The GSI is focussing on the former.
Landslides in India are primarily caused by monsoon rains. Of all the global landslides triggered by rainfall, 16 per cent are from India, according to GSI. When water infiltrates the soil, it fills the space between soil, sand, gravel, or rock, causing the soil to lose strength.
“Water from rain or snowmelt also makes the sediment more likely to flow. Imagine grains of sand and you put a thin layer of water between them, then one sand grain is more likely to flow over another,” Bruce Malamud, Professor at Durham University, England, told DTE.
Other triggers include rapid snowmelt, earthquake tremors, volcanic eruptions and disturbance by human activities like construction work, legal and illegal mining, unregulated cutting of hills and poor drainage.
The idea that landslides could be forecast emerged in the 1970s after researchers from Hong Kong, New Zealand, the United States and Japan found links between rainfall and landslide occurrence, reads a 2020 paper in journal Earth-Science Reviews. Russell H Campbell from the US Geological Survey is thought to have first proposed the possibility of forecasting rainfall-induced landslides using rainfall data in 1975.
“In the last three or four decades, our ability to predict landslides has improved substantially and it continues to do so,” Fausto Guzzetti, current research director of the National Research Council in Italy and an author of the 2020 paper, told DTE.
The first regional geographical landslide early warning system (LEWS) was set up in Hong Kong in 1977, which, like India, witnesses more rainfall-induced landslides. “Hong Kong shows us that a landslide early warning system can make a difference,” Guzzetti noted.
Since then, LEWS have been installed in the United States, Canada, Brazil, Colombia, Indonesia, Bangladesh, Taiwan, Italy, Scotland, Norway, Central America and the Caribbean, and Indonesia, the paper stated. “Top countries with LEWS are Hong Kong, Norway, Italy and Japan,” Kala Venkata Uday, associate professor at Indian Institute of Science in Mandi, Himachal Pradesh, told DTE.
Still, early warning systems across the world are far and few. A 2020 paper published in journal Frontiers Earth Sciences points out most of these LEWSs do not operate where a large majority of fatal landslides occur and the risk of landslides to the population is high. “Landslides do not capture the attention of the media as do earthquakes, volcanic eruptions, large floods, or hurricanes. Single landslides tend to cause less damage and fewer fatalities in comparison,” Guzzetti explained.
In India, GSI is working to operationalise the rainfall-induced LEWS prototype developed between 2016 and 2021 by nine partners from India, the United Kingdom and Italy as part of the LANDSLIP project.
The prototype was built in two regions of India: The Nilgiris and Darjeeling, which have suffered fatalities and socio-economic impacts due to landslides triggered by intense rainfall during the north-east monsoon (October to December), according to information available on the LANDSLIP project website.
“GSI signed a memorandum of understanding with the British Geological Survey to co-develop a suitable prototype model of regional landslide early warning for Darjeeling and the Nilgiris in the country to upscale and spread this knowledge further in other areas,” Ghosh explained.
This is the first part of a series on early warning systems for landslides. Read the second part here and the final part here.