Heavy rains caused devastating landslides in Kerala’s Wayanad district early on Tuesday morning. It occurred at Chooralmala near Meppadi and continued till Mundakkai village downstream. 251 people are confirmed dead, and many more are still buried beneath the rubble.

Authorities have been conducting significant rescue operations as settlements have been wiped away. The Army’s Southern Command has sent out helicopters and rescue teams. However, strong winds and continued rains have hampered the efforts of the National Disaster Response Force (NDRF), the Army, and local authorities to rescue.

Dismembered human parts and limbs were found kilometres away in the Chaliyar River—crumpled corpses buried in mud and dirt between the rocks. Entire areas, kilometres in extent, have been washed away! Mangled remains of vehicles and boulders the size of double-storey buildings lie strewn across the region.

Locals say that at least 300 people are missing. The landslide in Wayanad Mundakkai is becoming the biggest natural ‘disaster’ in Kerala’s history.

Before the wounds of Puthumala, Kavalappara, and Kottickal were completely healed, another massive landslide hit Kerala. Landslides used to be an occasional phenomenon, but after the 2018 floods, they became annual events. Since then, we have lost hundreds of lives. Even their bodies have not been recovered.

Studies and figures released in 2022 show that Kerala has the highest number of landslides in Bharat. Of the 3,782 landslides across the country in the last seven years, 2,239 were in Kerala. West Bengal, which stands in the second position, had only 376 cases. The figure is 196 in Tamil Nadu, 194 in Karnataka and 184 in Jammu and Kashmir. That means that 60 per cent of all landslides in the country are in Kerala!

Why do so many landslides occur in Kerala? What causes landslides? Who is responsible for this? What should we do to avoid landslides? This is also the time to consider such questions seriously.

Puthumala, a plantation village near Meppadi in Wayanad district, is 1230 m above mean sea level. Like Mundakkai, Puthumala (just 8 km away)was another plantation village near Meppadi. On 8 August 2019, heavy rainfall during the monsoon season and severe floods caused a landslide in Puthumala in the evening.

Before the big disaster, there were landslides in many places in Puthumala. The panchayat members and locals saw the disaster and evacuated many people, so the death toll was limited to 17 (mostly those who refused to leave). If the locals had not recognised the omens, perhaps the death would have exceeded a hundred.

The epicentre of the landside was 290 metres up on the mountain, and it knocked down 20 hectares of land, pushing it a distance of around 2 km. The rainfall data analysis revealed that the area got approximately 500 mm of heavy rainfall in the 24 hours preceding the landslip.

As per protocol, the situation in the surrounding villages should be studied if there is a landslide in one area. Not all the expert advice was considered or followed, resulting in the Puthumala landslide.

The same night, the Muthappanmala collapsed above Kavalappara colony near Nilambur Pothukkall in Malappuram district. Due to rising water in the nearby stream, locals who tried to move people to a safe place were instantly buried under the ground. It took time for the outside world to know about the disaster as communication systems were disrupted.

When the police and other people came to know about the incident, the Chaliyar River roared between Kavalappara and the rescue workers. When they somehow crossed that obstacle and reached Kavalappara, workers saw another hill below Muthappan Hill. 59 people were buried alive under that big hill that formed in seconds. 11 people are still somewhere under that soil. Even their bodies have not been recovered.

A landslide in Pettimudi, Idukki, on 6 August 2020 claimed 66 lives, and four bodies are still missing. In October 2021, incessant rain caused a landslide, bringing down rubber plantations in Koottickal (Kottayam) and Kokkayar (Idukki). Around 24 lives were lost in that tragedy, and several remain missing still.

After that, there were many small and big landslides. But have we learned any lessons?

Human activity worsened slope instability—the conversion of natural vegetation to plantations, step cutting of slopes, construction of soak pits causing water to infiltrate the slope, construction of homes on natural drainage channels, and improper drainage methods have all contributed to such tragedies.

Landslides are more prone in areas with a slope of 10 degrees to 40 degrees. Special attention is required if there has ever been a landslide within a radius of two kilometres. Studies have revealed that 13 per cent of the land in Kerala is prone to landslides.

Reports say that 95 per cent of landslides in Kerala are man-made. Cultivation on hillsides, mining of soil and rock, and construction of roads and buildings without considering the lay of the land, slope, nature of rocks, soil structure, trees, etc., disturb the balance of sloping surfaces and cause massive landslides and erosion. It leads to massive disasters, including the loss of human life.

50 per cent of Kerala’s land area is hilly. 35 per cent of the population resides in this region. Therefore, protecting the Western Ghats is very important for the Keralites.

Ecologist Madhav Gadgil is a name that Kerala remembers whenever there is a natural calamity. Keralites despised Gadgil’s report on the conservation of the Western Ghats in 2013.

Madhav Gadgil had earlier pointed out that 1700 illegal rock quarries are operating in the environmentally vulnerable areas of the Western Ghats in Kerala. “2700 quarries are working in the Western Ghats. 1700 of them are illegal. The Collector has not sanctioned them. The panchayats have denied permission to operate these quarries. But they still work,” said Gadgil.

Kenya and Nepal have experienced the most landslides in the world. But even there, the death rate is lower than in Kerala. That’s why we need to study this phenomenon even more.

Soil Piping

Soil piping is an underground erosion phenomenon. Inside the mountain, the soil is eroded in small channel widths, forming a series of tributaries, like a river, through which loose soil and rock fragments are washed away. This will weaken the entire soil in that area.

There will be no sign of such large tunnels forming underground or branching out. When it rains heavily, landslides happen unexpectedly. Geologists call this phenomenon ‘soil cancer’ because it spreads silently.

Geographically, Meppadi has a slope of more than 13 per cent. This again increased the risk of disaster.

When the trees on the hill are cut, their roots dry out and form large clumps. When it rains, much water collects in those piles and stays underground. Then, when it rains heavily, no more water can be stored, and the soil, stones and water from the top burst down.

Apart from this, the black laterate soil found in Wayanad has low water absorption capacity. There are also reports that due to continuous rains in the district for two weeks, the soil could not absorb all the water underground, which caused the landslide.

Soil piping was found to be the cause of the massive landslide that occurred at Puthumala in Kalpetta on August 8, 2019.

Such tunnels have been found near Banasurasagar Dam in Wayanad. The reservoirs of the Karapuzha Dam lie just 5 km from Chooralmala. Tunnels as big as a jeep can go through have been found in the state.

Realising the seriousness of the problem, the National Disaster Management Authority funded a research project collaboratively conducted by the National Centre for Earth Science Studies in 2016. Based on the recommendations of the research project, the State Executive Committee notified Soil piping as a State Specific Disaster.

To avoid soil piping, numerous steps can be implemented, including:

Proper compaction: Ensuring the earth is properly compacted during construction can help lessen the risk of soil piping. Well-compacted soil contains fewer voids and paths for water to pass through.
Use appropriate materials: Using erosion-resistant materials in important areas can help to avoid soil piping. Geotextiles and geosynthetic materials, for example, can give additional strength while reducing erosion risk.
Good drainage design: Proper drainage is required to keep water from collecting in the soil mass. Installing sufficient drainage systems, culverts, or surface water management systems can assist in diverting water away from sensitive regions.

Vegetation: Planting trees can help to stabilise soil and prevent erosion. Tree roots help to bind the soil together, making it more resistant to erosion and flooding.
Slope stabilisation: Proper slope stabilisation using measures such as terracing, retaining walls, or slope strengthening can prevent soil piping by lowering the possibility of soil movement.
Regular inspections of embankments, slopes, and other sensitive places can aid in the early detection of soil piping. Quick action can then be taken to rectify any issues before they worsen.
Overall, preventing soil piping necessitates good design, building procedures, and maintenance measures to assure soil stability and reduce internal erosion risk.