Landslide threat looms over high ranges; 5,000 incidents from 2015 to 2018

THIRUVANANTHAPURAM: Incessant rain in the Western Ghats poses a huge risk of landslides in the high-range areas of the state. Under the circumstances, the India Meteorological Department’s (IMD) forecast of a low-pressure formation over the eastern coast and its possible impact on the high ranges in the next few days has added to the fear of destruction to life and property in the event of a landslide.

Various studies have shown that extreme rainfall could trigger landslides in places with steep slopes and weathered bedrock. This season, a landslide has already happened near Munnar, on the second anniversary of the catastrophic Pettimudi landslide. Significantly, the high-range areas in the state are considered the most landslide-prone in the country. The data tabled in the Lok Sabha on July 27 shows the state witnessed 2,239 landslides -- accounting for 60% of the landslides in the country -- over the past seven years. 

However, an international study with the help of satellite images shows there were close to 5,000 landslides between 2015 and 2018. Idukki district is considered the most vulnerable to landslide in the event of a trigger like heavy rain. In 2018, the district saw around 2,000 landslides.

“Kerala is more vulnerable to landslides because it gets more rain and has a hilly terrain. If it happens in a populated area, it causes a lot of casualties. The amount of rain remains the most critical factor that triggers multiple landslides in the high ranges,” said Sajinkumar K S, an assistant professor with the geology department of Kerala University, and one of the authors of the study published in the prestigious journal Earth System Science Data.

“There is no cohesion between soil and the hard rock beneath it. So in the event of heavy rain, the soil gets too saturated as it can no longer hold water. The soil just flows and we call it a landslide,” he said.

The study shows that 2,503 of the 4,728 landslides caused damage to buildings, roads and agriculture. Conducted by Sajinkumar and experts from the Geological Survey of India (GSI), the study -- contrary to popular belief -- shows that man-made activities have a low contribution in triggering landslides. However, poor methods adopted in road and building construction too have contributed to landslips resulting in the destruction of properties, the study said.