Kolkata: Ill-planned roads and neglect of indigenous erosion-control measures in hilly areas like in Darjeeling in West Bengal cause landslides in India, an expert said on Thursday.
Incessant rains in Darjeeling hills triggered a series of landslides that have claimed at least 30 lives. The tourist spot will continue to witness "widespread and heavy" downpour in the next 48 hours.
"Widening and constructing roads in the plains is easy but in the hills it is a challenge. In the hills, there is a need for supporting and stabilising systems to protect the exposed surface of the hills due to construction," Chandan Ghosh, professor and head, Geo Hazards division, National Institute of Disaster Management (NIDM) said.
"The harsh truth is there is a lot of haphazard construction going on without following proper guidelines and without any supporting steps post-construction," Ghosh noted.
He said water accumulation was the root cause of rock, debris and earth sliding down slopes. This is because once the hills are cut open and exposed, water gets direct entry inside and drainage becomes a problem.
"If we take care of drainage, 80 to 85 percent of landslides which we are seeing every now and then in the rainy season can be avoided. Such measures cost around 1-2 percent of the road construction process," Ghosh said.
He said countries like Japan, where around 80-85 percent of the land area was hilly, does not experience such frequent landslides.
Further, Ghosh said landslides do not happen all of a sudden.
"Locals get inkling of certain anomalies, for example, water blockage and erosion. But attention is not paid to them," he said.
Given that the Himalayas is prone to landslides, Ghosh called for more vulnerability mapping of potential landslides locations and adoption of ground modification strategies like growing Vetiver grass, which is famed for its erosion-hedging properties.
"You cut the slope, you grow this grass, it stops erosion and tackles drainage issues. More than 100 countries have taken this grass from us. I have been trying to promote the use of this grass in Darjeeling for the last five years but unfortunately it is not being done," he lamented.
Vetiver grass has been used for centuries in south India and is known to be an important tool to reduce erosion (by up to 90 percent) and reduce and conserve rainfall runoff (by as much as 70 percent).