Landslides are a natural phenomena, but human intervention can exacerbate tragedies like the one in Wayanad in the south Indian state of Kerala. Three landslides struck the northern hill district of Kerala on Tuesday, killing more than 250 people — one of the biggest tragedies in the state.
Landslides are not new to Wayanad, a picturesque region that attracts hordes of tourists with its balmy weather and scenic vistas. On August 29, 2019, Puthumala — 5km away — was rocked by a landslide that claimed 17 lives. Two years later, there were more deaths in the regions which reeled from heavy rainfall and landslips.
What are the causes of landslides?
Landslides occur in mountainous regions with steep slopes. Large amounts of rock, boulders, loose mud, soil, and debris hurtle down hillsides at great speed, burying or destroying vegetation or buildings as they gain momentum.
Conditioning and triggers are two factors that lead to landslides. Conditioning factors include soil topography, rocks, geomorphology, and slope angles, which make some regions more vulnerable. The trigger factors are heavy rainfall and human interventions like unscientific road and building construction and large-scale forest destruction.
■ The panel recommended regulating construction activities in one of the world’s eight critical hotspots for biological diversity.
■ The panel included Vythiri, Mananthavady and Sulthanbathery taluks in Wayanad in ecologically sensitive zone-I (ESZ-I), meaning no land change was permitted.
■ It recommended banning mining, quarrying, new thermal power plants, hydropower projects, and large-scale wind energy projects in ecologically sensitive zone 1.
■ Following resistance from state governments, industries, and local communities, the recommendations are yet to be implemented even after 14 years.
What makes Wayanad vulnerable to landslides?
Wayanad is situated on the ecologically sensitive Western Ghats, which is vulnerable to landslides. Some parts of the district are also prone to soil piping, a naturally occurring hydraulic process that develops macropores (large, air-filled holes) under the soil surface. These are associated with landslides as water fills them and the earth beside gives away.
Did development activities increase Wayanad’s vulnerability?
Human intervention played a significant role in the landslides. Deforestation, unplanned construction and climate vagaries are responsible for the landslides in Wayanad, C.P. Rajendran, a geoscientist and adjunct professor at the National Institute of Advanced Studies, Bengaluru, told The Hindu newspaper.
Experts say rapid urbanisation and increasing mining activities in surrounding areas have made the region even more fragile. Construction activities create quarries, which become artificial lakes that affect the topsoil.
What are the other factors that make Wayanad a hotspot for landslides?
Large-scale migration from other parts of Kerala destroyed the forest cover as plantations sprung up in the hilly district. The area became more susceptible to devastating landslides without solid and deep roots of big trees.
“Most landslides in Kerala are around plantation areas, indicating another major triggering factor — agricultural activities such as monocropping, in which large, native trees, which hold the topsoil to the bedrock, are cut down. These trees are being replaced by big plantation crops, such as tea and coffee, which have shallow roots,” S. Abhilash, director of the Advanced Centre for Atmospheric Radar Research (ACARR) at Cochin University of Science and Technology, Kochi, told The Indian Express.
How much forest cover did Wayanad lose?
A study published in the International Journal of Environmental Research and Public Health said Wayanad had a forest cover of around 85% until the 1950s. However, a 2022 study showed that 62% of Wayanad’s green cover disappeared between 1950 and 2018, while plantation cover rose by around 1,800%, Business Today magazine reported.
What’s the link between deforestation and soil piping?
Deforestation, which started in the 1980s, must have changed the soil conditions. “The root systems of the [destroyed] forest trees left within the soil must have decayed, leaving huge cavities. Similar soil conditions with cavities under the soil cover must exist in the Mundakkai/Chooralmala area. It is possible that the water seeped into the cavities and interconnected underground channels formed by soil piping phenomena,” Rajendran said. Soil piping is often linked to landslides; Wayanad is a prime example.
Did Kerala’s tourism play a role in Wayanad’s landslides?
Wayanad’s scenic beauty has attracted tourists, leading to massive construction activities. Tourism resorts mushroomed, and roads were widened to bring more tourists into the district.
The Kerala government has proposed a four-lane underground tunnel between Anakkampoyil in Kozhikode and Meppadi in Wayanad to reduce the distance from 85km to 54km. Some reports said the landslide crown is close to the proposed tunnel site.
Did rain trigger the landslides in Wayanad?
Yes, it did. Loss of forest cover led to soil piping, making the situation in Wayanad precarious, experts said. Two weeks of continuous rainfall, 50-70% above normal, saturated the topsoil, and a day of extremely heavy rain set the sludge of mud, rocks and water racing downhill, destroying everything along the way.
A deep mesoscale cloud system formed off the coast in the Arabian Sea caused extreme rainfall in Wayanad, Calicut, Malappuram and Kannur, Abhilash said. “The clouds were very deep, similar to those seen during the 2019 Kerala floods,” he added.
How much did human interference contribute to the disasters?
“What happened in Wayanad was a disaster we consciously brought upon ourselves,” environmentalist V.S. Vijayan, who was part of the Gadgil committee, told India Today magazine.
“These are disasters in the making, rather than one-off events. When new, poorly designed settlements burden an already fragile environment, a small shock or stress is enough to aggravate the situation, and you recurrently witness events like Wayanad’s,” Abinash Mohanty, sector head for climate change and sustainability with research firm IPE-Global, told Bloomberg news agency.
Is climate change to blame?
Climate change is also a factor, as warmer air holds more moisture, leading to the development of vertical clouds that can discharge very heavy rains in a short amount of time, Yogesh Patil, chief executive of India’s largest private weather forecaster, SkyMet, told Bloomberg.
“Rainfall, which usually occurs in a span of 24 to 48 hours, is happening in a span of two to three hours. A heavy downpour is more dangerous in hilly regions as the water is channelised into a stream, and a decrease in forest cover increases this vulnerability,” he added.
What can be done to avoid similar disasters in future?
Global warming is expected to wreak havoc on weather and other climatic conditions, which will have a ripple effect on disasters worldwide.
“The frequency of landslides is likely to increase in hilly regions like Wayanad. Disaster management agencies should update landslide susceptibility maps. Satellite data and digital elevation models are now used to map the risk of landslides. The government must frame clear policies on land management based on these zoning maps,” Rajendran said.
“Long-term strategies should be developed to address annual floods and landslides in ecologically fragile lands. Kerala, with a high-density population, should initiate imaginative but humane initiatives on environmental management and new guidelines for land utilisation,” he added.
