New Delhi, Aug. 10: A surge flood with an over 30-foot-high wave at its head threatens to roll down from Tibet into Himachal Pradesh any time now.
It will swamp settlements, roads, bridges and the Rs 8,600-crore Nathpa Jhakri power project, a scenario for disaster management drawn up by experts has assessed.
China last week warned India that a dam created by a landslide in Tibet was likely to burst. But it is only today, after a preliminary assessment by the Central Water Commission (CWC) and the Union water resources ministry, that the magnitude of the disaster likely to hit Himachal is being felt in the administration.
As of this afternoon, water was flowing over the dam on the Pare Chu river in Tibet that was created by a landslide on July 27. The lake created by the dam is about 30 km from the India-Tibet border.
The first satellite pictures suggested that the landslide had formed a 150-hectare water body — with a depth of over 35 metres — inside Tibet. The Chinese have said the quantum of water in the lake is about 49 million cubic metres.
An assessment for the disaster management says:
• The flash flood caused by the dam burst will be of a magnitude that is twice that of a surge flood in August 2000 in Himachal when 100 people were killed.
• The discharge of water at the Rampur measuring station on the Sutlej, some 9 km downstream from the Nathpa Jhakri project, would be at the rate of about 10,000 cubic metres per second, double that in 2000. These figures are an estimate of the ferocity of the surge flood some 250 km from the India-Tibet border. Closer to the border, in Kinnaur, the scenario could be much worse.
• The Nathpa Jhakri project is at risk not only from the surging waters but mostly from the debris that will be hurled by the raging river. All turbines of the project have been switched off. All the gates have been opened. Efforts are being made to ensure that the water flows over the dam.
• The intensity of the flood will be minimised if the water surging from Tibet triggers another landslide or the debris chokes the river in its course and creates another lake.
• After the water rushes down swamping low-lying settlements, it will accumulate in the reservoir of the Bhakra Nangal dam. By that time, the flash flood in the Sutlej will have lost its ferocity. There is no immediate threat of a flash flood in Punjab into which the Sutlej flows from Himachal.
• Indian experts suggested controlled explosions of the dam to China but the Chinese are understood to have said the topography does not permit such risks.
The administration alerted villagers and towns along the Spiti and Sutlej rivers through which the flood will roar.
A crisis management group in the home ministry has asked the authorities to gauge the level of water in the Pare Chu every 30 minutes at the India-Tibet border.
Sources in the water resources ministry said the threat to human life this time was less than it was in 2000. This was because of an agreement with China to share data on rivers in Tibet.