The Hindu Business Line : Nathpa Jhakri suffers Rs 355-crore loss due to silting

THE 1,500-MW Nathpa Jhakri hydroelectric power project in Himachal Pradesh has suffered losses to the tune of Rs 355 crore on account of closure of the station due to high silt level in river Satluj since its commissioning in 2003.

"The total consolidated loss suffered by Satluj Jal Vidyut Nigam Ltd on account of forced closing of Nathpa Jhakri Hydro Electric Project units on account of high silt is about Rs 355 crore since its commissioning in 2003," the Minister of Information and Broadcasting, Mr Priya Ranjan Dasmunshi, told Rajya Sabha in a written reply.

The silt level in the Satluj river has been high during last two monsoon seasons, he said, adding generating units have to be closed when silt level exceeds the permissible levels to avoid any damage to the project.

According to a Power Ministry official, there was a shortfall in power generation at the station to the tune of 1,300 million units last year, largely due to a 10-day shutdown forced by the flood threat from the Pareechu lake in Tibet. This year again due to excessive flooding of the Satluj river because of the early onset of the monsoons, the project was forced to shutdown in order to protect the generating machinery from damage due to excessive silt and low discharge. Despite the precaution, the project was forced to operate below capacity for days together as the high-silt levels managed to damage the turbines, he said.

"The project faced higher than expected silt content in the river water this monsoon resulting in increased wear on the turbines. In August this year, the project was closed for nearly three weeks due to excess silt in the water, which was beyond the capacity of the desilting chambers," an official said.

In fact, closures due to silting was predicted in the design of the project, but even in the worst case scenario this was expected to be in the region of four to five days per year, officials said. "The project authorities are now in the process of determining the probability of the reoccurrence of such high silt loads as happened in 2005 and if any changes need be done in the project design to cope up with such a situation," an official said.

Government officials said it was yet to be established whether rapid deglaciation in the Satluj catchment area in China was responsible for the unexpected levels of silt.