About 800 families, mostly tribespeople, in the landslip-prone regions of Wayanad escaped the monsoon fury a fortnight ago after the district administration, on expert advice , relocated them to safer places in advance.
Geo-technical experts at the National Institute of Technology-Calicut had recommended the evacuation before the monsoon gained strength. “In April this year, the Wayanad District Collector requested us to provide solutions to specific areas of the district as we had investigated the floods and landslips last year,” S. Chandrasekharan, Professor, Department of Civil Engineering, NIT-C, told The Hindu.
Subsequently, a team led by him and Prof. K. Saseendran, also of the NIT-C and known geologist, gave a preliminary report, to the Wayanad district administration, urging them to shift the entire population residing at Pancharakolly, Trisselery, Makkimala, Sugandhagiri, Meppadi, Tirunelly, Mannyankunnu, Priyadrasini estate, and Boys Town. Landslips occurred in all these areas this August.
Unfortunately, the district administration did not request the team to study the region at Puthumala, near Meppadi, where 17 people were killed in a landslip this year. The National Centre for Earth Science Studies and the Geological Survey of India are yet to give reports in this regard.
Dr. Chandrasekharan said that an observation of the terrains had revealed that more landslips could occur in these areas if the monsoon was severe. “The slopes of hills were in the range of 30 to 60 degrees. These had been also been flattened to construct houses. Besides, the trees had been felled, thus giving a leeway for rainwater to infiltrate into the soil. Further, the rear sides of the houses were either vertical or concave shapes,” he said.
Causes
The human activities in the region had blocked the natural drainage patterns and internal drainage had developed. Consequently, the soil on the surface became saturated or submerged. And, the finer soil particles and small boulders drifted away in some places. It was found that multiple parallel cracks were formed in the ground causing severe damage to houses in this terrain.
“Some cracks had reached a maximum stage. A portion of the hills slide down by 1-2 metre vertically for a length of 500 m to one km. We warned that bigger landslips were likely to occur in these razed hills,” he said.
Like in other parts of the State, reclamation of paddy lands for construction works and blocking the flow of water have resulted in the natural calamities in Wayanad. The sudden change in crop patterns to banana from paddy and removal of grass for coffee also contributed to floods and landslips.
The mushrooming of quarries for M-sand and granite stones as well as construction of rainwater harvesting ponds in hills were other reasons to trigger landslips. Another serious issue was the laying of interlocked titles on the compound of the houses leading to increase velocity of surface flows, Dr. Chandrasekharan pointed out.
