Harbingers of calamity

The death toll from a series of landslides in Kerala has reached 358 at the time of filing this report with scores still missing as the southern Indian state reels from one of its worst disasters in years. Hundreds of homes were swept away and crushed by two huge consecutive landslides in the hilly district of Wayanad in the middle of the night last week. The landslides occurred after the steep terrain was hit by five times the normal amount of rain, with some regions reporting more than 300mm (1ft) of rainfall within 24 hours. Entire villages were submerged in mud as the large volume of rain caused the Iruvazhinji River to overflow and change course, gushing through places where hundreds of people were asleep in their homes. Several tea and cardamom plantations were also devastated.

Hundreds of workers participated in the rescue operations, pulling bodies from the mud and debris, facing continuous hindrances due to adverse weather conditions and access difficulties after key roads and bridges were washed away in the disaster. At the end of the second day of rescue efforts, about 190 people were still missing or unidentified, children among them, and fears were fading for their survival. The Indian Army evacuated more than 5,500 people from the area, including hundreds of stranded tourists, and took them to dozens of relief camps as the heavy rains continued. Areas previously with human habitation, turning into bare, flattened mud grounds, scattered with rock boulders, are now a familiar sight for the people of Kerala. The 2018 deluge that killed over 450 people shifted the state to a disaster-vulnerable state, with a consecutive flood in 2019 and devastating landslides in the years following. The state woke up to similar sights on July 30 with the administration quickly resorting to rescue operations and risk management, even as experts and environmentalists criticised the government for not developing a strategy for risk mitigation.

Floods are not uncommon in the country — or South Asia — at this time of the year, when the region receives most of its rainfall. But climate change has made monsoon rains more erratic, with massive rainfall in a short span of time followed by prolonged periods of dryness. Scientists now point to a particular phenomenon exacerbating conditions like atmospheric rivers. Also known as “flying rivers”, these storms are vast, invisible currents of water vapour formed over warm oceans. As seawater evaporates, the vapour forms a band or column in the lower atmosphere that moves from tropical to cooler latitudes, delivering substantial rainfall or snowfall that can trigger devastating floods or avalanches. These atmospheric rivers transport approximately 90 per cent of the mid-latitude water vapour across the Earth and typically carry about twice the volume of the Amazon River, the largest river by discharge. With global temperatures rising, atmospheric rivers are becoming longer, wider, and more intense, thereby increasing flood risks for millions of people worldwide.

Dr Roxy Mathew Koll, an atmospheric scientist with the Indian Institute of Tropical Meteorology has been quoted as saying: “There is increased variability in the moisture transported to the Indian subcontinent during the monsoon season. Consequently, atmospheric rivers can dump a significant amount of moisture in a few hours to a few days, resulting in more frequent landslides and flash floods across the country.”

As the climate continues to warm, the impact of these atmospheric rivers on India’s monsoon patterns and flood risks is expected to grow, presenting ongoing challenges for disaster management and mitigation efforts in the region.

The Hume Centre for Ecology and Wildlife Biology has been collecting, analysing, and sharing data on rainfall in Wayanad district, since 2018. “We have a daily updating system. The updates are put on a group in which all the stakeholders, like the District Collector and Disaster Management Authority people, are there. We have a clear daily analysis, providing separate data on highly saturated regions, averages about Panchayat, and district-wise details. Also, we have a grid that analyses the rainfall every 25 kilometres. Even on July 31, two regions crossed 4000 millimetres (mm) of rainfall; in two other places the rainfall was 3600 mm; this is heavy. Normally, rainfall would come to 3000 mm in the monsoon. But this year, it has been consistently heavy rains, and by July 20, soil became saturated in all regions. Soil saturation water-bearing capacity means streams would originate, water flows out of them, and heavy water inflow in all rivers,” CK Vishnudas, Director of Hume, has been quoted as saying in a report.

The district had witnessed landslides in the same region in 2020, and the authorities shifted people because of the alerts provided by Hume, he has claimed. “This year, our warning has specific details about soil saturation and the vulnerable regions, naming the villages that have been cut off. We had given an update about the intensive rainfall and a warning that this could be the expected rainfall in the region overnight, which could trigger a landslide,” he added. But there has yet to be a proactive step from the authorities. “This is something we could have avoided, I stand by that,” he asserted.

Meanwhile, in a Rajya Sabha speech on July 31, Union Home Minister Amit Shah said the Centre gave early warnings to the Kerala government on July 23, seven days before the incident. On July 26, he said, a warning was given that there was a chance of heavy rainfall of more than 20 centimetres and there were chances of landslides. He questioned why there was inaction by the state government despite the warnings.

However, Kerala Chief Minister Pinarayi Vijayan refuted the claim, saying that the Union Home Minister has presented information in Parliament that is inconsistent. The CM added that the India Meteorological Department’s warning was that rainfall would be between 115 and 204 mm. However, the actual rainfall – 572 mm in 48 hours – was much higher. The area received 200 mm of rain in the first 24 hours and 372 mm in the next 24 hours.

In a media report, S Abhilash, Director of the Advanced Centre for Atmospheric Radar Research at the Cochin University of Science and Technology (CUSAT) attributed the excessive rainfall to the cloudbursts from high water accumulation over the southeastern part of the Arabian Sea. The Arabian Sea lies to the west of Kerala. Earlier research by Abhilash and others found that rainfall over the west coast of India is becoming more convective. “Cloudbursts occurring under favourable ocean-atmospheric conditions may leave a vast area of the state vulnerable to flash floods and landslides anytime during the monsoon season. The paper (published in 2022) was based on the Kavalappara and Puthumala landslide. Post that, such disasters kept occurring, and landslides happened in Pettimudi (Idukki district) in 2020 in Koottickal in (Kottayam district) in 2021, and a major cloudburst in Kalamassery in Kochi (the first-ever cloudburst in the state in May 2024). As an indication of cloudburst, we cited the increasing depth of clouds forming in the southeastern Arabian Sea, causing increasing rainfall.”

According to him, the warming of the Arabian Sea and the increasing depth of clouds is a clear signal of climate change. He also blamed the authorities for not issuing a warning, sensing the pattern of the rains. However, sources in the government have been quoted as having rejected such a claim. Talking about the making of this disaster is the Iruvazhinji river, which originates at an altitude of around 1800 metres and flows down the three affected villages — Mundakkai, Chooralmala, and Attamala in Vythiri taluka — to finally merge with the Chaliyar river. The continuous sharp decline in the river’s elevation profile means it has more water and its water currents are stronger as it runs through inhibited areas. Officials say Vythiri received around 57 cm of rainfall in 48 hours, resulting in a swollen Iruvazhinji and landslides. To make matters worse, the landslide debris fell into the river — ultimately forming what survivors described as a wall of sludge that inundated villages upstream. Heavy rainwater running down into the river from hills above and a sharp slope seemed the disaster’s best friends. Remote sensing data shows Mundakkai, the first village along the river path that now falls flat and devastated, is situated at an elevation of around 950 metres — nearly half of the origin point in a distance of just over 3 km.

Experts speculate that vegetation could have lessened the impact. The non-implementation of the Western Ghats Ecology Expert Panel (WGEEP) report, led by prominent ecologist Madhav Gadgil, which warned against anti-environmental activities in eco-sensitive areas in Wayanad, has also been brought up by experts, after the recent landslide. Experts opine that the authorities have failed in risk mitigation which has been advocated for since the Cyclone Ockhi in 2017. They further state that calamities of lesser magnitude in the future should not be trivialised solely because the state witnessed something of this extent.

Views expressed are personal