Besides natural events like rain, road building and widening may have triggered the new landslides, which the report said “are often shallow and small but which nevertheless inflict fatalities, severe damage to infrastructure and traffic disruption”. The landslides were mapped in October last year.
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Most landslides on 247-km Joshimath road ‘fresh’: Study
A study that identified 309 landslides along the 247-km road between Rishikesh and Joshimath points out that “this road is strongly affected by landslides which has been previously described and attributed to the region’s fragility of slopes, focused rainfall and frequent seismicity”. It further stated that most landslides “seemed fresh”.
The study by Jurgen MeyRavi Kumar Kuntu, Alexander Plakias, Igo Silva de Almeida and Wolfgang Schwanghart was published in “Natural Hazards and Earth System Sciences”, which is a peer-reviewed journal.
The study, which mapped the landslides in October last year, used Google Earth to show that “21.4% of the recorded landslides with road blockages existed before”, “17.8% of the landslides were most likely reactivated by excessive rainfall because they could not be identified as road-blocking before the rains” and “a maximum, 60.8%, were not identifiable in the Google Earth imagery”.
In their study report on the area, the authors also commented, “We conducted a systematic survey of landslides and derived a statistical model that aims at quantifying landslide susceptibility along the NH-7 at a high spatial resolution. Our analysis relied on a GPS-based survey of landslides while travelling from Rishikesh to Joshimath shortly after a period of anomalously high rainfall.”
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The study report also mentioned that road construction was soaring in the Himalayas. In the past five years, 11,000 km of roads were built in the Himalayan states, adding that “the fragility of the landscape as well as slope undercutting and poor construction practices make maintenance of these roads challenging.”
The study also cited National Crime Records Bureau data stating “nearly 160 people lost their lives in Uttarakhand in landslide incidents in the last four years.”
“The road was widened by removing vegetation and excavating soil and rocks, potentially creating unstable slopes,” the report said, adding, “data indicates that 20-40% of the recorded landslides are reactivated slope failures which underscores that slopes are recurrently unstable during periods with intense rainfall.”
It further said that “slope failures along the road have led to fatalities in parts where roads were widened” and cautioned that “damages and fatalities may become even more frequent in the future”.
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The expert report added that “reduction of traffic may disrupt the cycle of increasing hazard and exposure in the route and commissioning of the currently ongoing 125km-long broad-gauge railway between Rishikesh and Karnaprayag might be an important step towards this goal.”