The Union Ministry of Environment, Forest and Climate Change’s nod to Kerala government to go ahead with the feasibility study for a new dam in place of the 123-year-old Mullaperiyar dam has not enthused people living in the downstream of the dam as the approval is subject to the condition that the dam can be built only with the consent of Tamil Nadu.
Tamil Nadu, which owns and operates the dam in Idukki, has already come out against the green nod. A top Tamil Nadu government official was quoted by New Indian Express as saying that it is a violation of the Supreme Court verdict’s 2014 verdict allowing the state to raise the water level and they would file a contempt of court petition against the ministry.
The August flood that took the water level in most of the dams, including Mullapperiyar, to the brim had confounded fears of people living in the downstream of the dam regarding their safety. They had hoped the government to address their concerns while reconstructing the flood-damaged assets.
The people in Idukki consider the construction of a new dam thereby in place of the existing dam as the only permanent solution to the problem. Though the state government had started a slew of redressal measures for rebuilding the losses, a large number of the people living in the downstream of the dam is living with fear.
This anxiety was reinforced by the recent floods though the Supreme Court had given permission for raising the water level of the dam to 142 feet and till 152 feet after adequate strengthening measures. How long this will last is the big question worrying the people in Kerala.
The lease agreement signed with the British in 1886 for the transfer of water for 999 years will only be complete in 2885. Will the fragile dam continue for another 800 or more years? Expert opinion and the accepted norms are against this. The International Dam Safety Authority (IDSA) gives a lifespan of 70 years for a dam.
The Mullaperiyar dam was constructed when the technology was in its nascent stage. The cementing material used for the construction of the dam was Surki mixture. This too poses askance over the safety of the mammoth structure.
“A minor tremor at any time can lead to the destruction of a number of dams including the Idukki dam which exceeds Mullaperiyar in storage capacity,” says senior geologist AV George, who currently works as a professor of Geology at the Adama Science and Technology University, Ethiopia. He warns about the dam-induced earthquake that occurred at Koyna in Maharashtra in 1967.
Kusala Rajendran, a professor at Centre for Earth Sciences, at the Indian Institute of Science, Bangalore and an eminent seismologist says that a magnitude 6 earthquake cannot be ruled out in south India.
“In the event of such an earthquake in the proximity of the Mullaperiyar dam, one cannot predict the response of the dam to the earthquake, especially if it is shallow (within 5-10 km) which is generally observed depth range for the southern peninsular earthquakes. That concern apart, one has to look at the stability and strength of this 123 years old dam, which was constructed before the age of earthquake-resistant designs and is not made with cement. Considering the large population that lives downstream of the rivers that are damned by both the Mullaperiyar and Idukki dams, ensuring the safety of these dams is crucial. Global examples show that old dams are decommissioned. It is all the more important to consider such options and to maintain the water level at an optimal level because of the high density of population that lives downstream. The inundation levels of the 2018 flood post opening of the shutters of these two dams should serve as a good learning experience,” says Kusala.
K Soman, a former senior scientist-geologist from the Central for Earth Sciences, said that the scenario is grave. “Taking into consideration the recent floods, there is anxiety regarding the safety of the dam. A torrential rain accompanied by landslides as happened very recently coupled with a moderate scale earthquake can be disastrous,” says Soman.
V Nandakumar, group head of the crustal programmes of the National Centre for Earth Science Studies (NCESS) Thiruvananthapuram, says that considering the antiquity of the dam it is susceptible to mild tremors. Most of the other dams were constructed using most modern technologies they have safety measures which is not the case of Mullaperiyar, he says.
The structural stability analysis of the Mullaperiyar dam in the year 2009 conducted by DK Paul of the IIT Roorkee's department of earthquake engineering had found that the Mullaperiyar dam and the Baby dam are supposed to sustain damages in the wake of an earthquake leading to the failure of the dam.
In the case of the main dam, damages were predicted over the occurrence of an earthquake having the magnitude of 6.5 in the vicinity of the dam (within 16 km) when the water level in the dam is 136 feet. These studies also support expert opinions.
As per the dam break analysis report conducted by the water resources development and management of the IIT Roorkee in 2012, the water level down the Mullaperiyar dam would rise by 40.30 m and in Idukki dam, which is about 36 km from Mullaperiyar, the level would go up to 20.85 m, if anything adverse happens to the reservoir. The dam break analysis report says about the possibility of the ‘over-topping mode of failure for the dam which is reasonable for dam break flood generation’. The IIT Roorkee had evinced an interest to conduct a new study on the rainfall pattern in view of the recent floods.
More than 30 lakh people of the state are living with a Damocles sword hanging over them owing to the age-old weak presence of the dam. Tamil Nadu is using the water from the Mullaperiyar dam for fulfiling the agricultural purposes of more than 13,000 acres of land. Kollam MP and former water resources minister NK Premachandran said that the dam should be decommissioned since it is not safe.
“If the rainfall recorded at Idukki dam was recorded at the catchment area of the Mullaperiyar dam, the dam would have toppled. The central government and the apex court should intervene,” he says.
Advocate Russel Joy, who recently filed a writ at the Supreme Court seeking the decommissioning date of the dam which has completed its lifespan says that an expert commission should visit the Mullaperiyar dam and they should study on the basis of the The American Federal Guidelines for the Safety of Dam so as to ensure the safety of the dam. In his writ, he demanded that Tamil Nadu should compensate to the beneficiaries who are living in the downstream of the dam in the course of the breakage of the dam.
The water is reaching Tamil Nadu through a big tunnel having the length of 5,220 feet and the width of 150 square meter. A portion of the water is reaching the lower camp power station and the rest to the Vaigavanar project. The water reaches Vaiga dam through the Theny river.
The Mullaperiyar’s relation with Tamil Nadu is due to the lease agreement signed by the King of Travancore Sri Vishagham Thirunal at the Special interest of the Governor of Madras at the behest of the British government. Though the British government persuaded Sri Vishgham Thirunal to sign the agreement for diverting the water of the Periyar river form 1962 onwards the King resisted it for over 24 years over the interest of his people and finally gave in. The condition of the agreement of 1886 when the construction began only permits to give water for the purpose of irrigation and not electricity production.
The main purpose for the construction of the dam was the irrigation of the agricultural lands of the Theny and Madurai districts in the Madras Presidency. The state received a paltry Rs 5 for an acre for the 8,000 acres of land involved in the lease agreement with the Tamil Nadu.
The lease agreement extending to 999 years culminating only in 2885 authorises to maintain the 8,000-acre land of the state at the hands of the British government. After the British left, Tamil Nadu holds the authority to maintain this lease agreement.
The state didn’t take the needed care for ending the lease agreement, though Tamil Nadu violated the lease agreement on various occasions and it stands cancelled after the exit of Britishers.
Updated Date: Oct 24, 2018 18:30:42 IST