Heavy rains and recurring tremors in Kerala’s Idukki district have triggered panic among people living downstream of the 116-year-old Mullaperiyar dam at Thekkady. The district administration issued a high alert on November 27 after the water level in the reservoir rose to the safe storage level of 136 feet (41.45 metre) and beyond due to continuous downpour in the Periyar river's catchment area. Control rooms have been opened for helping people in case of emergency.
Experts have warned that the ailing dam, which has been a bone of contention between Kerala and Tamil Nadu for more than three decades, would not survive a major earthquake. What's more, four mild-intensity tremors, measuring up to 3.4 on the Richter scale, hit areas downstream of the dam on Saturday even as people were panicking over increased leaks from the dam, caused by the previous tremors on November 18.
1886: The Travancore Princely State and British Presidency of Madras sign the lease deed; the deed gives the British the right to divert "all the waters" of the Mullaperiyar to the British territory (the Madras Presidency, now Tamil Nadu) for 999 years. 3,237.5 hectares of forestland handed over for a lease amount Rs 5 per acre.
1947: Treaty lapses following the Indian Independence Act, 1947.
1970: Kerala and Tamil Nadu sign a formal agreement to renew almost completely the original deed
1979: A Central Water Commission inquiry team suggests the water level be lowered to 136 feet (41.45 metres) from 142.20 ft (43.34 m) at that time for carrying out dam strengthening work. After the completion of the work, the water level could be raised to the full reservoir level (FRL) of 152 ft (46.33 m)
2000: Kerala begins questioning the legality of the original lease deed; Tamil Nadu approaches the Supreme Court. Central government intervenes in the dispute
2001: Kerala refuses to increase the water level. Tamil Nadu approaches court
2006: Supreme Court allows storage level to be raised to 142 feet. Kerala promulgates a new "Dam Safety Act" against increasing the storage level; apex court does not object to it
2009: Union Ministry of Environment and Forests grants environmental clearance to Kerala for conducting survey for new dam downstream
2010: Supreme Court constitutes a five-member empowered committee to study all the issues of Mullaperiyar. The report is to be submitted in February 2012
Though the dam is in Kerala, it is totally controlled, managed and operated by the Tamil Nadu government as per a lease agreement between the two states (see 'Disputed dam'). The purpose of the dam was to divert water from the west-flowing Periyar to the rain shadow region of the Madras Presidency (now Tamil Nadu) on the eastern side of the Western Ghats. Water from the dam is used only by Tamil Nadu.
How strong is the structure
The dam has cast a shadow of fear on people living in Idukki and downstream areas. “We have been living in constant fear for the past many years. It’s as if we’re sitting on a time bomb,” says C P Roy, a college professor and coordinator of the Mullaperiyar Action Council, a people's organization that has been agitating for de-commissioning of the unsafe dam. “For us it’s a question of life and death, not a political issue,” says Roy.
The panic among people is not baseless. The dam falls in quake-prone area and as many as 26 tremors have hit the region in the past eight months. In December 2000 and January 2001, the region was hit by tremors of magnitude of up to 5 on the Richter scale. Seismological studies by the Geological Survey of India have placed southern and central Kerala in Zone III, where earthquakes with magnitude six and above are possible. Further, a 2009 report submitted to the state government by a team of experts from the Indian Institute of Technology at Roorkee says the dam cannot withstand quakes of magnitude more than 6.4.
Apart from the possible impact of tremors on the ageing dam, the deteriorating structure itself is a matter of concern, say experts. The dam, one of the oldest in the world, has far outlived its predicted life span of 50 years. The dam structure is 438.91 metres long and 48 metres high and is 1,097.28 metres above sea level. The front and rear faces of the dam are of rubble masonry in lime mortar. Concrete with sandstone and surkhi mortar (a mixture of sugar and lime) forms the core. It was built for a gross storage of 441.75 million cubic metre (MCM) water.
“Mullaperiyar is a gravity dam, and for a gravity dam its weight is its strength,” says A V George, head of the department of Geology and Environment at Christ College in Irinjalakkuda. He has studied the safety aspect of Mullaperiyar extensively. Over the years, 38 per cent of the lime from the core is estimated to have leaked out, making the dam much weaker, says George. Cracks, leaks and seepage have made the structure damp and wet.
The maximum water level in the reservoir had been lowered to 136 feet (41.5 metres) in 1979 on the advice of the Central Water Commission (CWC), after the dam developed leaks. CWC had advised construction of additional spillways to avoid the risk of water level rising in the reservoir. The Tamil Nadu government is demanding that the maximum permitted reservoir level should be raised to the original 152 feet (45.33 m) because the state had carried out works to strengthen the dam. But out of the 13 new spillways, only a few are functioning. Further, the dam has shutters much higher at 142 feet (43.28 m) and above, which means at the present critical water level of 136 feet, there are no shutters and so water cannot be let out fast. When rains are heavy, water level in the reservoir rises fast, at times by nearly two metres in a single day.
A five-member expert committee, appointed by the Supreme Court last year for conducting a detailed study on the safety of the dam, is expected to submit the final report in February.
If Mullaperiyar dam were to collapse, flash floods will reach Idukki dam 35 km down stream within 45 minutes, washing away four towns on the way—Vallakkadavu, Upputhara, Chappath and Vandiperiyar. These have a total population of more than 70,000. Idukki dam has a storage capacity of 1,982.19 MCM but it may not be able to hold the entire water from the Mullaperiyar if the dam were to fail during monsoon.
“Taking into consideration the steep topography of the region and the elevated position of the Mullaperiyar dam, the velocity of the flash flood will be about100-150 km per hour,” says George. The high-velocity flash flood would bring down much soil and floating debris which can clog spillways and exert considerable stress on the dam.
If Idukki dam fails, then 11 more dams downstream will get breached and the flash flood will run through four districts with a population of 3.5 million, and the port city of Cochin, before it merges with the Arabian sea. Kerala, is a narrow, slanting strip of land, between the Western Ghats and the sea. “It will be a huge disaster,” says George. On Tuesday, the four districts that would be affected—Ernakulam, Alappuzha, Kottayam and Pathanamthitta—observed a protest strike. The Mullaperiyar Action Council, which has been demanding safety for people in downstream areas, has, meanwhile, started an indefinite fast.
Plenty of words, little action
In Kerala, the ruling Congress-led United Democratic Front (UDF) and the CPI(M)-led opposition, Left Democratic Front (LDF), and people’s representatives, cutting across party lines, say they are committed to protecting peoples’ lives. Taking a serious note of the recurring tremors and the grave consequences if the dam breaches, an all-party meet was convened by chief minister Oommen Chandy on November 23. The leaders concluded there is an urgent need to build a new dam and dismantle the existing one. On Monday, MPs from Kerala, cutting across party lines, raised the dam safety issue in both houses of Parliament and stalled proceedings, demanding Centre's immediate intervention.
“The government is extremely worried about the safety of people,” says Kerala water resources minister P J Joseph. “What we want is a new dam to ensure the security of the people here.” As a temporary step, the party leaders proposed reducing the dam's storage level to 120 feet (36.58 metres) from the present 136 feet (41.45 metres) and urged Tamil Nadu to cooperate. According to chief minister Chandy, Kerala's stand is: “water for Tamil Nadu and safety for Kerala”.
But apart from making a public outcry about the safety of millions of people and the urgent need to build a new dam, the state government has not done what it could have easily done without the Centre’s intervention or Tamil Nadu’s cooperation: formulating an effective and efficient disaster management plan. So far, the government has not even drawn a potential loss map.
“In the context of a dam disaster, the government needs to plan the following in detail: how to evacuate people, where to rehabilitate them, what should be the resource bases, giving proper awareness and training to people how to act without panicking, establishing warning systems in the downstream districts,” says George. A preliminary disaster management plan prepared by a three-member team of scientists in 2007, as per the instruction of the then revenue minister K P Rajendran, is gathering dust.
What Tamil Nadu stands to lose
If the dam fails, Tamil Nadu, too, would be a big loser. Agriculture in the districts of Theni, Madurai, Dindigul, Sivaganga and Ramanathapuram would be hit without the Mullaperiyar dam. Tamil Nadu diverts about 640mm3 (about 637 MCM) water from the Mullaperiyar reservoir annually for irrigation and generation of hydro-power. It irrigates about 13,000 ha of land in the drought-prone districts. If the dam fails, there could be mass suicide by farmers in this region.
But Tamil Nadu is strongly opposing Kerala’s proposal to build a dam, asserting the present reservoir "is as safe and good as new" and has accused Kerala of whipping up fear psychosis.
As per the original agreement, the Travancore Maharaja leased out 3,237.5 ha of forestland from the Periyar basin to the Madras government for a lease amount Rs 5 per acre (0.4 ha). This amount was raised to Rs 30 in the renewed agreement between Kerala and Tamil Nadu governments signed in 1970. As per this agreement, Tamil Nadu pays an annual amount of Rs 2,40,000 for the land and Rs 7.5 lakhs for the electricity it generates. But a new dam means a new agreement, and a new agreement may cause the state dearly, if one considers the money Tamil Nadu pays to Karnataka for Kaveri water.
“But more than the economics, water is a political and emotional issue in Tamil Nadu,” points out social activist and ecologist C R Neelakantan. He also feels the permanent solution may not be building a new dam. When the lease period is 999 years, and if the life span of a dam is taken as 100 years, then at least nine dams will have to be built across the Periyar at Thekkady, which is a wildlife sanctuary and one of India's tiger sanctuary. Even if a new dam is the only solution, it cannot be built overnight. “It will take a minimum of two years, and what if something happens in between?” he asks. “It is high time that Kerala and Tamil Nadu governments sit together with the Central government and find out proper solutions keeping away narrow political interests and stopping emotional outbursts,” says he.
Environmental scientists like Shivaji Rao, direcor of environmental studies at GITAM University in Visakhapatnam, who has studied the Mullaperiyar dam, suggest cultural leaders, intellectuals, social activists and environmentalists should take a lead in sorting out the dispute and not leave the matter in the hands of politicians and bureaucrats. "Ït's not a question of Kerala or Tamil Nadu, but an issue of the fundamental right of people to lead a safe and dignified life," he adds.
The Kerala government, meanwhile, gave an undertaking to the Centre on Monday that it would continue to provide water to Tamil Nadu as is being given now, if a new dam is constructed in the place of the old one. Also, the state would construct the dam from its own funds. This assurance in writing, as sought by Union Water Resource Minister Pawan Kumar Bansal a few days ago, was jointly given by the state water resources minister Joseph and and revenue minister Thiruvanchoor Radhakrishnan.
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