Part 3: Clean chit to the Tapovan Vishnugad Hydroelectric Project for water leakages, landslides not occurred in areas with low population density
Joshimath in Uttarakhand has been facing the issue of land subsidence for almost five decades, the Geological Survey of India (GSI) said in its report investigating the causes of landslides in the region early this year. The report gave a clean chit to the Tapovan Vishnugad Hydroelectric Project and noted that landslides have not occurred in areas with a lower population density.
This is the third of a five-part series by Down To Earth, examining the reports by eight agencies looking into the issue, one by one. Following the Uttarakhand High Court’s directive, the state government released the reports of eight agencies, including the GSI report. The report was submitted back in February 2023.
In the report, GSI identified 81 cracks in Joshimath. Of these, 42 cracks are recent, related to the recent occurrence of subsidence reported on January 2, 2023, while the remaining cracks are old.
Read more: Himalayan plunder: Why Sikkim geologists fear Joshimath-like disasters
Previous GSI research indicated that Joshimath is located on a slope with a lot of loose and unorganised debris. As a result, problems with subsidence, slipping, and settling are not uncommon in the Joshimath area, the report said. These have been reported on several occasions over the last 4-5 decades.
The Sunil Gaon, Manohar Bagh, Singdhar, and Marwari wards have seen the majority of the recent cracks in the ground, according to the report. These wards fall almost in a straight line from bottom to top, whose width is around 50-60 metres.
Cracks primarily appeared in densely populated areas, the report further stated.
The agency also investigated the water oozing out near JP Colony. Apart from that point, dirty water is not leaking out from any other point in Joshimath, the paper found. This point is located in Marwari, the lowest part of the affected areas.
The water flow reduced from 600 litres per minute (LPM) on January 2, 2023 to 17 LPM on February 2, 2023, which shows that there was a lot of water accumulated there and as the water pressure decreased, the incidence of land subsidence increased.
Read more: Himalayan plunder: Increasing landslides in Himachal result of ‘development work’, say experts
Subsurface research by the Central Ground Water Board and the National Geophysical Research Institute (NGRI) has also revealed that the source of water flowing near JP Colony in Marwari is directly connected to an aquifer beneath the densely populated area. The aquifer is 18-48 metres thick and may be directly related to the landslide in Joshimath.
The water leak in JP Colony has no possible connection with the head race tunnel of National Thermal Power Corporation or NTPC Ltd’s Tapovan-Vishnugad Hydroelectric Project. Many locals and some experts had alleged a link between the water leak and the NTPC tunnel.
NTPC’s tunnel is located at a lateral distance of about 1.1 kilometres from the urban extension of Joshimath, the GSI said. About 3.5 km of tunnel were being excavated using the drill and blast method (DBM), but this area is four km away from Joshimath. Therefore, prima facie, the question of any damage caused by the explosion is very unlikely, the findings stated.
Joshimath town is located within the Uttarakhand segment of the active Himalayan Fold-Thrust Belt (FTB), the GSI further said. This part of the Himalayan FTB is restricted by several linear elastic shear zones, which divide it into several tectonic slices of different dimensions. It is bound by the Main Boundary Thrust in the south and the Indus Tsangpo Suture Zone (ITSZ) in the north.
The region also exposes the rocks of the Central Crystalline Group, which pass over the rocks of the Garhwal Group, where Chamoli and Pipalkoti are located.
There are two main perennial streams present in the eastern part of Joshimath city, which are AT Nala and Parasari Nala. They join the Dhauliganga river flowing north-east, while another perennial stream Jogidhara, flows in the western part of the city. Jogidhara flows in the north-northwestern direction and joins the Alaknanda river.
There are many waterfalls within the city of Joshimath as well. They are all being considered for being the cause of the landslides.
To read the first part of the series click here and click here to read the second part.
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A house standing almost on the verge of collapse in Singhdhar area of Joshimath. Photo: Raju Sajwan.png)
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