The proposal for a new dam at Mullaperiyar is not in the best interests of Kerala. It should press for phased decommissioning the dam while ensuring water supply to Tamil Nadu, at least for a few decades in reduced quantities.

A new dam means handing over the problems to another generation, about 50 to 100 years from now. This is also what the Maharaja of Travancore did by leasing land for 999 years. But that was because his hands were forced. Kerala has to see that this would not happen again.

Feasibility of new dam
Mullaperiyar dam site is in a seismically active area. Even though technologies are now available to build earthquake-resistant dams, it is still advisable not to build dams near fault lines. The area also falls in the Periyar Tiger Reserve and National Park. Various clearances including forest clearance will be required to build a dam there. An environmental impact assessment will have to be done and this is not going to be very favourable. The Gadgil Committee on Western Ghats has already called for decommissioning of old dams on the Ghats. Construction of new large dams on the Ghats is no more considered an environmentally sound proposition.

There are actually few locations along the course of the river for building a new dam. The one proposed is downstream of the present dam on land not leased to Tamil Nadu. Kerala is already saying that it would build new dam on its own and will not be willing to lease additional land to Tamil Nadu. Tamil Nadu will object to its losing ownership and control over the dam. Use of this land will require denotificaton of the sanctuary area required for expanding the reservoir. This, in turn, necessitates a resolution by the Legislature and approval by the Centre.

New technologies will be needed if Tamil Nadu proposes to build a dam upstream of the present one and even that will require negotiation of a new agreement between Tamil Nadu and Kerala and environmental clearances. There will be specific objections to building dams that will store water above the current full reservoir level which is fixed at 142 feet by the Supreme Court. The negotiations between Kerala and Tamil Nadu can prolong for any number of years, given their history of reviewing the Parambikulam-Aliyar Project agreement.

The construction activity, once started, is going to cause serious disturbance to wildlife in the area. This will hinder environmental clearances and invite protests. Issues like lower riparian rights of Kerala too have to be considered while proposing a new dam. (Lower riparian rights are internationally recognised. They, among other things, specify that a certain amount of water should be allowed to flow down while damming a river.)The adequacy of spillways of Idukki dam to handle additional flow too will have to be considered, especially in view of the recent change in weather patterns.

In fact, there is hardly any justification for building a new dam in national park on the Western Ghats. Full scale inter-basin diversion of river waters is not permissible even in other areas these days.

Kerala’s incapacity to build dam
Though Kerala says it can build the dam, the work would have to be entrusted to an outside party, probably to a multi-national consultancy and dam-builders. The State Water Resources did not have the capability to build such a dam in a time bound manner. Two its last projects, Edamalayar and Kallada were plagued by cost and time over-runs and corruption. The State Electricity Board too doesn’t have experienced engineers for this work, though it once had the capability. (The Board neglected its civil wing and engineers who have designed and executed large dams have all retired). The State Public Works Department is recently in the lime light for faulty construction of buildings and bridges and corruption.

Though a former Water Resources Minister had boasted that the dam could be completed in a year, nothing like that is ever going to happen in that Department. We have engineers who always stated that the Mullaperiyar dam is unsafe but could not prove before the Supreme Court that a 120-year-old dam posed sufficient risk to attract the precautionary principle! (So, the government thought that a retired jurist, who incidentally believed that the dam would be safe for another 100 years, was a better option to represent Kerala in the Committee set up by the Supreme Court.)

Phased decommissioning
Given this scenario, the best option is to press for phased decommissioning of the old dam. Tamil Nadu has not so far accepted Kerala’s long standing demand for new dam. So, it is time that Kerala focus on the demand for decommissioning of the dam and not fall into the trap of building a new dam.
Former Union Secretary for Water Resources Ramaswamy R. Iyer has said that it will be a folly to build a new dam on Mullaperiyar. “We can start thinking of phasing it out. That means giving people time to get adjusted to this idea and seek alternative sources of economic activity, and perhaps a different pattern of development that does not require so much water,” Mr. Iyer said in an interview to Frontline magazine published in December 2011.
“Accept the fact that the dam is not going to be permanent. Explore alternative means of supporting the livelihoods of people who will be affected by the phasing out of the dam,” Mr. Iyer said.
The phased decommissioning of the dam, which he suggests, will not be without problems. Currently, there is no means to lower the reservoir level of Mullaperiyar dam beyond 136 feet other than drawing of water through tunnels by Tamil Nadu. This is because the saddle spillways are at 136 feet. The capacity of tunnels is limited to 2200 cusecs and will be inadequate to manage flows caused by floods which will exceed the capacity of tunnels.
There is a proposal that Tamil Nadu should build a new intake tunnel at the level of 50 feet from the base. (The present intake is at 104 feet and water below this level could not be drawn). The techno-economic feasibility of this proposal has been questioned by some engineers. But new technology may help, though it may be costly. The Mullaperiyar dam does not have a sluice gate at the bottom for emergency discharge of water. There was a proposal for a tunnel to downstream of Mullperiyar River for discharge of water, but it has not come up for serious consideration despite the risks posed by the dam.
It is often convenient for Kerala politicians to call for new dam. But the proposal does not suit current thinking on environment and river management. Building a new dam will be a folly as pointed out by Mr. Iyer. Instead of undertaking such a foolish proposal, Kerala should demand a time table for phased decommissioning of the old dam.

Related link: A dam has a life— Frontline report, December 2011.