Shimla, August 15
With the Chinese authorities asserting that allowing water to flow out in a natural way from the huge lake formed in Tibet due to blockage of the Parchu rivulet is the safest option, the water body is likely to become a permanent feature and a matter of perpetual concern for the state.
The blockade has survived the crucial phase during which the size of the lake and the water level rose at an alarming rate and overflow started but the high alert has not been scaled down as the threat of a flash flood due to a sudden gush of water could not be ruled out. The lake has been overflowing steadily and this has been confirmed by the latest satellite images. The satellite images also reveal that the parameters of the lake have not changed over the past 48 hours, indicating that the water body is gradually
stabilising.
The Chinese authorities have stopped giving specific data about the lake like the size, inflow and outflow though the hotline. It has informed the government that the hotline will be used only to give a warning in case of a sudden increase of outflow or the bursting of the dam. All other information regarding the status of lake will be provided through diplomatic channels on the request of the country.
Meanwhile, a five-member team comprising two experts from the Central Water Commission, and one each from the Geological Survey of India, the Survey of India and the Sutlej Jal Vidyut Nigam visited Lapcha, the point where the Parchu enters the country from Tibet. The team studied the course of the river and the topography of the mountainous region. It suggested setting up of a permanent centre to measure the discharge of the river at Lapcha. The team will give its detailed report to the Government of India tomorrow.
The engineers of the Nathpa-Jhakri project maintain that there was little likelihood of the blockade giving way abruptly. The sheer size of the blockade, measuring 178 m along the river and 84 m across it, made it evident that the barrier created was “very strong” though a host of other factors like the nature of strata and topography of the site would play a vital role in determining its strength, says Mr J.K. Sharma, an expert on dam engineering.
Mr H.K. Sharma, Director Civil, Nathpa-Jhakri project, expressed similar views. A man-made earthen or rock-filled dam is of a much smaller size. A 40 m high dam will have a maximum base of 100 m whereas in the instant case the blockade was 174 m along the river at the base and as such should be highly stable, he explains.
The water body is, thus, here to stay at least for the time being. More so because satellite images show that a crater existed at the site and for the past few years, the lake had been appearing and disappearing. The water body will become stable once the outflow exceeds the inflow as water level will start
centre to measure the discharge of the river at Lapcha. The team will give its detailed report to the Government of India tomorrow.
The engineers of the Nathpa-Jhakri project maintain that there was little likelihood of the blockade giving way abruptly. The sheer size of the blockade, measuring 178 m along the river and 84 m across it, made it evident that the barrier created was “very strong” though a host of other factors like the nature of strata and topography of the site would play a vital role in determining its strength, says Mr J.K. Sharma, an expert on dam engineering.
Mr H.K. Sharma, Director Civil, Nathpa-Jhakri project, expressed similar views. A man-made earthen or rock-filled dam is of a much smaller size. A 40 m high dam will have a maximum base of 100 m whereas in the instant case the blockade was 174 m along the river at the base and as such should be highly stable, he explains.
The water body is, thus, here to stay at least for the time being. More so because satellite images show that a crater existed at the site and for the past few years, the lake had been appearing and disappearing. The water body will become stable once the outflow exceeds the inflow as water level will start declining. This could well happen over the next two weeks as the melting of glaciers which feed Parchu will slow down with the falling temperature. With this, the flash flood threat will also subside. By November, when the mercury dips several degrees below freezing point, the inflow and outflow would come down to a trickle as the surface of the lake will also be frozen.
However, the flood threat will be revived from May onwards as the water level in the lake, perilously perched on the heights of Tibet, start rising again. As such, a long-term strategy will have to be worked out to ensure that the perpetual threat of flood does not paralyse normal life in the villages located along the banks of the Sutlej.
There has been no change in the situation over the past 24 hours. The Parchu has been flowing normally with a slightly increased discharge since yesterday morning. The Nathpa-Jhakri project remained shut down and a decision to restart generation will be taken tomorrow by the committee under the Union Cabinet Secretary, monitoring the situation.
