Retired Chief Engineer M. Sasidharan, who is a member of the Inter State Water Advisory Committee, has said that the waters from the Mullaperiyar dam would not be contained in the Idukki reservoir in case of failure of the Mullapeiryar dam.
Mr. Sasidharan, who was extensively involved in the monitoring of 44 dams in the State, told The Hindu that the Cheruthoni and Kulamavu dam would be at risk even if the water level in the Idukki reservoir is kept low.
Failure of the Mullaperiyar dam would unleash unimaginable force stronger than an earthquake and the force would be transferred to the dams of Idukki project - Idukki, Cheruthoni and Kulamavu. Kulamavu was the weakest of these dams. Though Idukki dam might survive, other two dams could fail. He said that the Idukki reservoir was 1200 feet below the Mullapeiryar dam and waters would be rushing down at 50 to 60 km an hour through a 10 km gorge downstream of the Mullaperiyar. Then it would flow down a 15 km slope down to the Idukki reservoir. The water column, which could be 20 to 30 feet high, would wipe out everything on its way and bring down a lot of earth and debris into the reservoir. The chances of part of the water taking courses other than that of the Periyar into the Idukki reservoir too could not be ruled out.
The force of water would be so high that it could even move away hills. In a note given to leaders of political parties who attended the all-party meeting on Tuesday, Mr. Sasidharan said that huge waves of very high magnitude would be generated by gushing waters from the Mullaperiyar dam in case of failure, and the inherent forces of such waves are unimaginable.
“The huge volume of 12 TMCft of water spread out in an area of 4668 acres when gushed through an opening of the present Mullaperiyar dam, the height of water that will rise along its path to Idukki is unimaginable. The enormous force that is created by the surging water when it reaches the Idukki reservoir will create huge waves, just like tsunami waves, in Idukki reservoir.
“The nature and magnitude of such waves could be very high, and it can generate great forces on the Idukki dam structures, especially Kulamavu masonry dam structure first, as the dam was constructed with rubble masonry. This could happen even if the water level in the reservoir is low.”
He added that apart from generating high stress on the three dams holding Idukki reservoir, the surging waves could overtop all the three dams. No studies had been carried out so far about the nature and magnitude of such huge stresses that would be generated on the three dams, and about the height of waves that would be generated in the reservoir which could ultimately overtop and damage these three dams.
He suggested that the water level in Mullaperiyar should be reduced to 120 feet as an emergency measure as that would reduce the pressure on the Mullaperiyar dam. New dam should be constructed as expeditiously as possible.
Kerala could start work on the dam immediately upon getting clearances form Ministry of Environment and Forests and on directives of the Dam Safety Authority. The Authority had powers to direct replacement of dam that posed threat to human life and property. Approval from Tamil Nadu was not required. He further suggested that the Central government could constitute a committee of senior Ministers including A. K. Antony and give assurance to Tamil Nadu regarding supply of same quantity of water as before.
