Kerala land has lost its “immunity” and landslips and related phenomena are here to stay.
The State must prepare to deal with it for a long time to come, V.R. Haridas, hydrogeologist, who studied the August 2019 Kavalappara and Puthumala landslips as advisor, Climate Adaptive Project for the National Bank for Agriculture and Rural Development. says.
The soil structure has changed drastically. It is no longer “immune” to events such as intense rain, as witnessed over the past two years and this year, Dr. Haridas, drawing an analogy from COVID-19, says.
“Land will continue to slip and slide and destroy lives unless pre-emptive measures are adopted. Soil is sensitive like the human body. Any interference with its nature and structure will have its consequences. One of the most common human activities has been massive deforestation, mostly for plantations. Mono-cropping and quarrying are other serious interferences with the structure and lay of the land,” he says.
When trees are cut and their roots are left to rot, they decay over decades to form pipes through which the soil substrata is directly injected with rainwater. This results in the formation of a sludge-like slippery layer that oozes to the hard rock resulting in the layer above the hardest rock losing grip and stability.
The conditions this week have been ideal for this type of phenomenon. Kerala’s rain is traditionally over a period of two to two-and-a-half months.
But now about half the 3,000 mm of annual rain is received in about one or two weeks.
It is like pelting the earth with stones, he says, pointing out that the nool mazha or yarn rain, which irrigated the land at a pace so suited to farming activities, is a thing of the past for Kerala.
Munnar and neighbouring areas received about 30 cm of rain over 24 hours in the last couple of days. Any volume of rain above 24 cm is classified as extremely heavy.
Dr. Haridas says the phenomenon of piping from large-scale root decay after deforestation takes about three decades. This was quite obvious in places where landslips had occurred in the past, including at Kavalappara, where 59 people lost their lives.