The year 2024 has seen a devastating series of landslides worldwide, from Yunnan, China in January to the Vellarimala hills in Wayanad, Kerala in July, resulting in significant loss of life and widespread destruction.
The most recent landslides in Meppadi, Waynad district, have claimed over 200 lives, with at least 240 people still unaccounted for and around 200 injured.
The twin landslides unleashed a torrent of muddy water and massive boulders, obliterating the Mundakkai and Chooralmala settlements in Meppadi panchayat and transforming a once picturesque hilly landscape into a scene of utter devastation and chaos.
Globally, landslides were previously underestimated as a natural disaster, perceived as less destructive than floods or droughts, until the catastrophic 2013 Kedarnath landslide. However, their frequency and impact are escalating as climate change intensifies, resulting in substantial loss of life and livelihood.
A landslide is characterized by the downward movement of rock, earth, or debris along a sloping terrain, typically triggered by rainfall, but also potentially caused by seismic activity or volcanic eruptions. This definition encompasses the complex and often devastating nature of landslides, which are becoming increasingly significant due to the effects of climate change.
Following the landslides, the Indian Space Research Organisation’s (ISRO) National Remote Sensing Centre (NRSC) released satellite imagery revealing that approximately 86,000 square meters of land had slid down the hillside. The affected area’s run-out zone extends roughly eight kilometers along the path of the Iruvanjipuzha, a significant tributary of the Chaliyar river, which flows adjacent to the impacted region, originating from the crown zone of the hills.
What does the study suggest?
A team from IIT-M has created a high-resolution India Landslide Susceptibility Map (ILSM) utilizing advanced machine learning models.
As reported in IIT-M’s Shaastra magazine, the ILSM reveals that a staggering 13.17% of India’s land area is prone to landslides, surpassing previous estimates. Furthermore, a significant 4.75% of the country’s area is classified as highly susceptible to landslides, highlighting the need for enhanced monitoring and mitigation efforts.
Research conducted by a team from the Central Coastal Agricultural Research Institute in Goa, published in 2020, suggests that the Puthumala landslide originated as a smaller-scale event deep within the forest.
However, as it progressed downhill, the landslide intensified and gathered momentum, particularly in the lower sections of the hill, where the soil structure was weakened and saturated with rainfall, making it increasingly fragile and prone to further erosion.
The initial smaller landslide transformed into a colossal slide, comprising a massive amount of rocks and mud, which led to a significant portion of the hill collapsing. The intense rainfall served as the primary catalyst, reaching a critical threshold that set off a chain reaction, ultimately triggering the devastating landslide.
What could be the triggering factors?
The widespread deforestation that began in the 1980s, aimed at clearing land for tree plantations, likely altered the soil conditions in the region over time. The removal of native forest trees meant the loss of their extensive root systems, which previously held the soil in place.
As these root systems decomposed, they left behind large voids and cavities, compromising the soil’s stability and increasing its susceptibility to erosion and landslides.
Additionally, water may have infiltrated the cavities and underground tunnels created by spoil piping, further destabilizing the soil.
Moreover, the likelihood of uncontrolled and unregulated activities such as unscientific construction and quarrying in the area may have exacerbated the risk, cumulatively contributing to the development of this hazard.
These human-induced factors may have compounded the natural vulnerabilities, ultimately leading to the catastrophic landslide event.
Soaring climate change
Given the projected intensification of climate change and global warming, the likelihood of landslides in hilly regions like Wayanad is anticipated to increase.
To mitigate this growing risk, it is essential for agencies responsible for landslide susceptibility mapping, such as the State Disaster Management, to regularly update and refine existing maps.
This proactive approach will enable more accurate identification of vulnerable areas, informing targeted prevention and preparedness measures to minimize the impact of future landslide events.
It is becoming even more crucial for the state to device clear policies on land management based on such zoning maps by taking the people into confidence.
Furthermore, it is crucial to develop and implement long-term strategies to combat the recurring floods and landslides that disproportionately affect vulnerable populations, who are often compelled to inhabit ecologically sensitive areas due to socio-economic circumstances.
Given Kerala’s high population density, the state should pioneer innovative yet compassionate approaches to environmental management, incorporating revised land-use guidelines that balance human needs with ecological sustainability, to ensure a safer and more resilient future for all.
Warming of Arabian Sea
According to the director of the Advanced Centre for Atmospheric Radar Research at CUSAT, the unusually heavy rainfall in Kerala can be attributed to intense cloudbursts resulting from the accumulation of high-water levels over the southeastern Arabian Sea, located west of the state.
This phenomenon is consistent with previous research by Abhilash and others, which suggests that rainfall patterns along India’s west coast are becoming increasingly convective. Under favorable oceanic and atmospheric conditions, cloudbursts can lead to a heightened risk of flash floods and landslides across a vast area of the state during the monsoon season, making it essential to remain vigilant and prepared.