Dehradun: 20 July, 2015
Experts have discovered that the massive crack on Varunavat Parvat near Uttarkashi was formed because of the poor quality of slope treatment methods used on the mountain after an earlier landslide. Meanwhile, Uttarkashi residents live in fear of landslides after the crack was formed.
On September 24, 2003, a series of landslides on Varunavat affected more than 3,000 residents, burying structures including houses, government buildings and tourist accommodations. Twelve years later, Uttarkashi is once again in the grip of panic after the crack, which is 20 metres long and nearly 15 cm wide, developed on the Tambakhani face of the mountain. Nearly 6,000 people live at the base of the Tambakhani face today and will be directly affected by any landslides on the mountain.
The crack has also raised questions about the quality of slope treatment of the mountain after the 2003 landslides. A team of geologists from the Disaster Management and Mitigation Centre (DMMC) surveyed the crack on Varunavat Parvat and are going to submit their findings by Tuesday. TOI has learnt that the DMMC experts found out that the crack developed due to erosion and weathering caused by incessant water flow from a drainage outlet constructed during the slope treatment. The erosion has also led to falling of rock material above the Tambhakhani tunnel, especially during rains.
"The crack has emerged on bench number 13 of a treated flank on the Tambhakhani side of the mountain. A piece of concrete bench on the right side of the crack has also subsided due to the erosion of rock material and soil beneath the bench," said Piyoosh Rautela, executive director of DMMC, talking to TOI.
The survey further revealed that the slope treatment done after 2003 was incomplete and drainage water was not properly channelized, which caused the erosion and finally resulted in the crack. "The water coming out of the drainage outlet on bench number 13 was directly hitting the rocks and soil, causing erosion. The outlet should have been treated also to avoid such a crack," said a DMMC geologist.
The DMMC experts, however, are of the view that the crack does not pose any threat to the people living at the toe of the hill. "However, it should be treated at the earliest to avoid any damage in future," said Rautela.
Uttarkashi district magistrate Indudhar Baurai said that teams from the Geological Survey of India (GSI) and Tehri Hydro Development Authority (THDC) will be reaching Uttarkashi on Tuesday to study the crack in further detail.
"The district administration will wait for the DMMC experts' recommendation. At the moment, we have not evacuated anybody as the rock material is only falling above the Tambhakhani tunnel, which is uninhabited. Evacuation would be done, if needed, once the treatment of the crack begins," Baurai told TOI.
Following massive landslides in the area in 2003, the government had announced a package of Rs 282 crore for slope stabilization of Varunavat. Consequently, corrective measures were taken to reduce shear stress and increase the mountain's shear strength, which included slope treatment, sealing cracks and developing a proper drainage system. Retaining structures were also built along the toe of the mountain close to Ramlila ground, Horticulture Colony and Masjid Mohalla. According to the experts, the standard procedure in such situations is to fill the crack and also remove the underlying rock and loose soil so that the crack does not widen.
Courtesy: Times Of India