Even as the works to restore the roads to Sabarimala gathered pace ahead of the annual pilgrim season, a landslide susceptibility mapping of the Mannarakulanji–Pampa stretch of the road leading to the hill shrine has found that many places in the area are highly prone to slope failure.
The study, conducted by the National Centre for Earth Science Studies (NCESS) last month, also found that about 100-150 meters of the road section at Planthottam and another location, which is two kilometers towards Pampa, particularly fell in the high-risk category.
Fearing that the cracks on the road at Planthottam could effect a landslide, the study has called for caution “as the whole stretch of that road section is likely to fail in the coming intense rainfall period”.
“The uphill part is also in a very vulnerable state. Most likely, the area will experience a rotational type of landslide,” it said.
To address the issue, the NCESS has proposed slope stability measures including provision for drainage, construction of reinforced walls, and laying of geotextiles, among other things.
“In the present scenario, combined geological, geophysical, geotechnical and remote sensing investigations should be carried out considering the importance of the area. Geological studies may involve detailed, field, structural and soil geochemical studies. Geophysical studies include resistivity, GPS surveys and geotechnical investigations for understanding the slope stability and safety parameters. Remote sensing studies should be conducted using very high resolution DEM data and susceptible area should be demarcated,” it said.
Further, it has also called for a scientific evaluation of the impact of the climate change on near-surface processes, as most of the slope failures in the highland regions of Kerala are triggered by high-intensity rainfall.
The PWD road, which is the only motorable road leading to Pampa to access Sabarimala, developed cracks at Planthottam during the heavy rains that lashed the district in August this year. Following this, the Sabarimala Special Commissioner M. Manoj submitted a report in the Kerala High Court that fissures had developed on the road close to the present location during the torrential rain of 2018 as well.
The report also called for a study to assess the possibility of soil piping and the subterranean flow of water needed to rule out the probability of landslip.
