Unscientific constructions, particularly on hill terrains, have resulted in several landslips during the recent floods, Geological Survey of India (GSI) deputy director general C. Muraleedharan has said.
Speaking on ‘Natural disaster: mitigation and management,’ at a programme organised by the Kerala Sasthra Sahithya Parishad here on Friday, Mr. Muraleedharan said the unscientific practice of taking up construction at areas prone to landslips and at areas where landslips had occurred in the past often led to casualties and loss of property. He cited various instances, including that of Government College, Munnar, which had been constructed on landslip-prone areas and suffered extensive damage in the recent floods.
“Very often, various factors, including unscientific slope modification, unprotected slopes in hill areas, construction on sloped terrains, lack of measures for water drainage and unscientific water management result in landslips. Surprisingly, such instances occur not due to the lack of knowledge, but the unscientific nature of project planning and execution with scant regard for possible repercussions,” he said.
He said 4,689 landslips were reported by the National Remote Sensing Centre (NRSC) during the recent floods.
Excess rainfall
While the State received 18% excess rainfall during the first spell of the southwest monsoon from June 8 to 30, the region witnessed severe downpour from August 1 to 19 with the second spell recording 164% excess rainfall—758.6 mm—as opposed to the normal rainfall of 287.6 mm.
“Most of the landslips in Kerala were due to the heavy downpour on the loose scree material in hill terrains,” Mr. Muraleedharan said.
Idukki, Palakkad
Around 1,600 landslips occurred in Idukki district alone, spread across revenue and forestland. Besides, roughly 1,400 landslips, of which 80% were in forestland, were reported from Palakkad. The GSI had deployed 10 teams to various parts of the State to undertake field studies, he said.
The GSI had also been simultaneously undertaking a macro-scale landslip susceptibility mapping of the State under the National Landslide Susceptibility Mapping programme. The programme, which was launched in 2014, aimed at preparing a landslip susceptibility map for an area spread across 18,854 sq km, covering parts of Western Ghats and its foothills, in the State.
The thematic maps prepared using the data collected would be stored in the geospatial database, which would be available for future reference and research. Site-specific studies would also be conducted in high-susceptibility areas at a later stage. With around 12,000 sq km covered, the mapping was expected to be completed by 2020, he said.
