PremiumA report by the Indian Space Research Organisation (ISRO) on Joshimath's land subsidence has gone missing from NRSC-a government-run website.
The report, which was released yesterday, pointed out that the land in Joshimath sunk 5.4 cm in just 12 days between 27 December and 8 January.
Further, the report claimed that the land subsidence was slow between April and November 2022, during which Joshimath had sunk by 8.9 cm.
The pictures were taken from the Cartosat-2S satellite.
“The region subsided around 5 cm within a span of a few days and the areal extent of subsidence has also increased. But it is confined to the central part of Joshimath town," National report Sensing said.
It said a subsidence zone resembling a generic landslide shape was identified – tapered top and fanning out at the base.
The report noted that the crown of the subsidence was located near Joshimath-Auli road at a height of 2,180 metres.
The images show the Army Helipad and Narsingh Temple as the prominent landmarks in the subsidence zone that spans the central part of Joshimath town.
Following the report went public, fear loomed among the locals. The District Disaster Management Authority said 25 more families were evacuated yesterday, taking the total number of such families to 185.
Meanwhile, Hindustan Times has reported that the Central government has refuted the theory that land sinking in Joshimath is related to the NTPC's hydropower project.
Environmentalists, geologists as well as locals have said that tunnelling associated with National Thermal Power Corporation’s (NTPC) 520 MW Tapovan Vishnugad Hydropower Project near Joshimath town led to an aquifer burst, leading to land subsidence in the holy town.
However, the Centre in its draft report said that the possible causes for the land subsidence in Joshimath town and the surrounding area include overburdened dump materials, underground saturation resulting from poor sewerage, inadequate surface run-off disposal, rainwater, and household wastewater, previous flood events causing natural drainage, toe erosion along the left bank of Alaknanda river, occasional heavy precipitation, periodic seismic activities, and increased construction activities.
Yesterday, an NTPC official made a similar statement.
State-owned NTPC told the power ministry that 12-km long tunnel connected to the Tapovan Vishnugad hydroelectric project is 1 kilometers away from Joshimath town and at least a kilometer below the ground.
Stating that land subsidence in Joshimath is a very old issue with first observance dating back to 1976, NTPC citing a state government-appointed M C Mishra Committee of that year blaming "hill wash, natural angle of repose, cultivation area because of seepage and soil erosion" for the subsidence/cracks.
The construction work of the 4x130 MW Tapovan Vishnugad project started in November 2006. The project includes the construction of a concrete barrage at Tapovan (15 km upstream of Joshimath town).
The project was to be completed in March 2013 but almost 10 years later, it is still 'under construction'. The project has also undergone a major cost escalation from the initial approved investment of ₹2,978.5 crore to now an anticipated ₹7,103 crore.
"Construction of the tunnel in this stretch has been done through Tunnel Boring Machine (TBM) which causes no disturbance to the surrounding rock mass," NTPC said.
The company said during the construction of the tunnel, locals had raised concerns about the drying of the water table in the future in the Selong area, which is about 6 km away from Joshimath Town.
NTPC also told the power ministry that there was no active construction work happening in the area for about two years.
The state government has begun demolishing unsafe buildings in the town and some residents have been relocated to safe places.