The 125th anniversary of the opening of the Mullaperiyar dam was on October 10.

An aerial image of the Mullaperiyar dam surrounded by greenery
news Infrastructure Monday, October 12, 2020 - 18:21

Former Kerala Water Resources Minister NK Premachandran, a current Member of Parliament, has demanded that the state government frame a case in the Supreme Court on the basis of the floods that occurred in the state in 2018, and utilise the provisions of the The Dam Safety Bill, 2019 to convince the apex court of the safety concerns regarding the Mullaperiyar dam.

Premachandran said that the state government should cautiously approach the apex court to highlight the feeble condition of the Mullaperiyar dam and the rise in water levels in dams in Idukki in 2018 due to flooding. “Taking into account the antiquity of the dam, we need a new dam sooner or later. In that context, the state government should frame a case before the apex court citing the above reasons that we need the new dam at the earliest,” Premachandran added.    

According to the Dam Safety Bill, 2019, “The dam owners will be responsible for the safe construction, operation, maintenance and supervision of a dam.” Tamil Nadu owns and maintains the Mullaperiyar dam, though the dam is situated in Kerala. The Supreme Court in its 2015 verdict had given permission to raise the water level of the dam to 142 feet, and till 152 feet after adequate strengthening measures. Experts are also rallying for a new dam in the place of the current dam.

Joshy KA, a former chief engineer with the Irrigation Department who supervised the dam on several occasions, told this reporter that a new dam is the only solution as the existing dam's structure is questionable.

“The existing practice across the globe is to decommission age-old dams. It is in this context that we perceive the Mullaperiyar dam. To maintain the Mullaperiyar dam at a seismic zone where occurrence of an earthquake is a probability is like planting a big bomb and waiting for it to explode. The structure of the dam has become weak owing to the antiquity of the dam." he said.  

Joshy noted that Tamil Nadu has not implemented the decisions of the supervisory committees. “That should be changed and the committee's decisions should be properly implemented. The solution is to construct a new dam and changes in the lease agreement should be made. To maintain the status quo will be damaging the lives of lakhs of people living in three to four districts," he said. 

Raising pertinent questions regarding the safety of the Mullaperiyar dam, noted geologist Dr AV George, who conducted studies on the dam, demanded the state government to make a representation at the Supreme Court to seek clarification on how long the water level in the dam should be maintained at 142 feet.  Dr George raised this demand on the 125th anniversary of the opening of the Mullaperiyar dam on October 10. The dam was opened after construction in 1895.     

Senior Seismologist Dr Kusala Rajendran cautions that the age of the dam and its structure is a concern. “Even a large flood that overloads the dam can be a concern (as it happens in the times of unpredictable climate change),” she added.

In regards to the Idamalayar and Periyar fracture zones converging near the dam, Dr Kusala, who is a professor at the Centre for Earth Sciences at the Indian Institute for Science, Bengaluru, said that no zone in the peninsular of India can be considered absolutely free from a high-intensity earthquake, such as the one that had occured at Koyna and Latur. She says the largest earthquake in the vicinity of the dam occurred at Erattupetta in 2001, which recorded 5.0 on the Ritcher scale.

“The lime content in the Surkhi mixture is less than one-third of the normal cement and it shows a lack of the strength. The unburned lime will wash away at the pressure of water. This can be understood through the chemical analysis of the drainage water. When we conducted the chemical analysis test of the drainage water, there were traces of unburned cement up to 30 to 35 percent. This will create porosity inside the dam and the structure has become weak as a result. The density of the dam is very low when compared to a structure built with ordinary cement. In order to strengthen the dam, the Central Water Commission (CWC), constructed a 10 metre-wide concrete wall behind the present dam to strengthen it. If a 4.0 earthquake occurs within a 10-kilometre radius of the original dam constructed with lime surkhi mixture, it will damage it,” said N Sasidharan, a former dam safety authority member and retired Chief Engineer Civil, who supervised the dam on various occasions. He said that the Mullaperiyar dam was constructed when dam technology was nascent and it has no earthquake resistant design.

According to the current apex court verdict, the water level in the dam should be continued in the current level due to the agreement signed by Travancore king Vishgham Thirunal in 1886 October 21 with the erstwhile Madras Presidency. “The lease agreement was for 999 years and will come to end only by 2885. The questions are whether the water level in the dam will be maintained till the lease agreement comes to an end? That is virtually impossible considering the frail condition of the age old dam built out of Surkhi, not cement,” Dr George adds. The International Dam Safety Authority (IDSA) gives a lifespan of 70 years for a dam. 

IIT Roorkie’s structural stability analysis

The structural stability analysis of the Mullaperiyar dam conducted in 2009 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.  As per the dam break analysis report conducted by the water resources development and management of the IIT Roorkee in 2012, the water level of 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.’

A brief history of the construction of the Mullaperiyar dam   

The construction of the Mullaperiyar dam began by 1886. A British engineer named John Penniquick was in charge of the construction activities of the dam. The construction activities were hindered twice due to the torrential flow of water in the river Periyar. Though the Madras government planned to abandon the project, engineer Pennyquick began construction of the dam by using the amount from his properties sold in England. The main purpose of the proposed dam then was for agricultural irrigation of the Theni and Madurai districts in the Madras Presidency.  The agreement came to be known as the ‘Periyar lease agreement’,  which was prepared by Ramayyangar, JC Hanington, and KK Kuruvila for the British council secretary.   Kerala gets a paltry Rs 40,000 for rupees 5 for the 8,000 acre land including the dam and lake as part of the agreement. 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.

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