Mullaperiyar Dam is a masonry gravity dam on the Periyar River. It is located 881 m (2,890 ft) above mean sea level in Idukki District of Kerala. It was constructed between 1887 and 1895 by the British Government to divert water eastwards to Madras Presidency area (the present-day Tamil Nadu).
The Mullaperiyar Dam is a gravity dam made with limestone and surkhi (a mixture of crushed brick, sugar and quicklime). Gravity dams use their weight and the force of gravity to support the reservoir and remain stable. The main dam has a maximum height of 53.6 m (176 ft) and length of 365.7 m (1,200 ft). Its crest is 3.6 m (12 ft) wide while the base has a width of 42.2 m (138 ft). It consists of a main dam, spillway on its left and an auxiliary dam (or "baby dam") to the right. Its reservoir can withhold 443,230,000 m3 (359,332 acre·ft) of water, of which 299,130,000 m3 (242,509 acre·ft) is active (live) storage.
On 29 October 1886, a lease indenture for 999 years was made between the Maharaja of Travancore, Visakham Thirunal Rama Varma and the British Secretary of State for India for Periyar Irrigation Works, after 24 years negotiation between the Maharaja and the British. One may wonder how can a lease agreement of 999 years be made for a dam with a design life of 50 years. The lease indenture granted full right, power and liberty to the Secretary of State for India to construct make and carry out on the leased land and to use exclusively when constructed, made and carried out, all such irrigation works and other works ancillary thereto to. The agreement gave 8000 acres of land for the reservoir and another 100 acres to construct the dam. The tax for each acre was INR 5 per year. The lease provided the British the rights over "all the waters" of the Mullaperiyar and its catchment basin, for an annual rent of INR 40,000.
Mullaperiyar dam was constructed to provide water to the rain shadow region of Madurai which was in dire need of a greater supply than the small Vaigai River could give. The dam created the Periyar Thekkady reservoir, from which water was diverted eastwards to via a tunnel to augment the small flow of the Vaigai River. The Vaigai was dammed by the Vaigai Dam to provide a source for irrigating large tracts around Madurai. As per the original lease agreement, the dam waters were used only for the irrigation of 68,558 ha (169,411 acres). Later, the Periyar Power Station in the lower Periyar, Tamil Nadu was built which generates hydro-electricity (175 MW capacity) from the diverted waters in the Periyar Power Station constructed in 1956. This was the first violation of the original lease agreement.
In 1947, after Indian Independence, the lease agreement expired. After several failed attempts to renew the agreement in 1958, 1960, and 1969, the agreement was renewed in 1970 when C Achutha Menon was Kerala Chief Minister. It was a blunder to renew the agreement due to two reasons.
- The design life of the dam was 50 years. The dam constructed in 1895 has already served the cause for 75 years.
- Tamil Nadu has already violated the original lease agreement by generating electricity from the the diverted water since 1956.
Instead of canceling the agreement and negotiating a new one, the Government of Kerala accepted the agreement as such with minor modification in the lease amounts.
According to the renewed agreement, the tax per acre was increased to INR 30, and for the electricity generated in Lower Camp using Mullaperiyar water, the charge was INR 12 per kiloWatt per hour. Tamil Nadu uses the water and the land, and the Tamil Nadu government has been paying to the Kerala government for the past 50 years INR 2.5 lakhs as tax per year for the whole land and INR 7.5 lakhs per year as surcharge for the total amount of electricity generated. The validity of this agreement and several other issues are under dispute between the States of Kerala and Tamil Nadu. The matter is currently pending before a Division Bench of the Supreme Court.
The dam is an 'endangered' scheduled dam under the Kerala Irrigation and Water Conservation (Amendment) Act, 2006. The dam and the river are owned by and located in Kerala. But the dam is controlled and operated under a period lease by Tamil Nadu state. The safety of the dam has been a matter of concern. Control and safety of the dam and validity and fairness of the lease agreement have been points of dispute between Kerala and Tamil Nadu states.
After the 1979 Morvi Dam failure which killed up to 25,000 people, safety concerns of the aging Mullaperiyar dam's and leaks and cracks in the structure were raised by Kerala Government. Centre for Earth Science Studies (CESS), Thiruvananthapuram found out that the structure would not withstand an earthquake above magnitude 6 on the Richter scale. The dam was also inspected by the Chairman of Central Water Commission. On the orders of the CWC, the Tamil Nadu government lowered the storage level from 142.2 feet to 136 feet, conducted safety repairs and strengthened the dam. Strengthening measures adopted by Tamil Nadu PWD from 1979 onwards include cable anchoring of the dam's structure and RCC backing for the front slope. The mistakes in the strengthening works carried out by Tamil Nadu damaged the masonry of the dam.
Current safety concerns hinge around several issues. Since the dam was constructed using stone ruble masonry with lime mortar grouting following prevailing 19th century construction techniques that have now become archaic. Seepage and leaks from the dam have caused concern. Moreover, the dam is situated in a seismically active zone. An earthquake measuring 4.5 on the Richter scale occurred on June 7, 1988 with maximum damage in Nedumkandam and Kallar (within 20 km of the dam). Consequently several earthquake tremors have occurred in the area in recent times. These could be reservoir-induced seismicity, requiring further studies according to experts. CESS, IIT Roorkee and IISc have reported that the dam cannot withstand earthquakes above 6 point on the Richter scale.
Kerala did not object giving water to Tamil Nadu. Their main cause of objection is the dams safety as it is as old as 116 years. Increasing the level would add more pressure to be handled by already leaking dam. Tamil Nadu wants the 2006 order of Supreme court be implemented so as to increase the water level to 142 feet (43 m).
In September 2009, the Ministry of Environment and Forests of Government of India granted environmental clearance to Kerala for conducting survey for new dam downstream. Tamil Nadu approached Supreme Court for a stay order against the clearance; however, the plea was rejected. Consequently, the survey was started in October, 2009. On Sept. 9, 2009 stated it had already communicated to the Government of India as well as to the Government of Kerala that there is no need for construction of a new dam by the Kerala Government, as the existing dam after it is strengthened, functions like a new dam. This is in fact the first water dispute which does not involve dispute on the quantity of water supplied.
What we should do next?
Precautionary Principle is a philosophical approach to risk prevention by taking protective measures against specific environmental or safety hazards in order to avoid or reduce environmental or safety risks. This approach was subsequently adopted in various International agreements. Precautionary Principle must be invoked
- Where the scientific evidence for safety is insufficient, inconclusive or uncertain.
- Where preliminary scientific evaluation suggests that effects on the environment, health or safety may be unacceptable and/or inconsistent with the chosen level of protection.
- Precautionary principle may be applied without waiting for the reality and seriousness of those risks to become fully apparent.
This principle was laid down in the Rio de Janeiro Declaration on Environment and Development of the United Nations Conference on Environment and Development (1992), in which India is a signatory. The due jurisprudence implied in the Rio instruments are international in impact and it cannot be violated by signatories like India.
Moreover, a number of important international conventions have incorporated this principle, including conventions on Climate Change and Biological Diversity. The Periyar National Park in Thekkady, a Protected area of Kerala, is located around the dam's reservoir, the 26 sq. km (10 sq mi) Periyar lake. 62 different kinds of mammals have been recorded in Periyar, including many threatened ones. Periyar is a highly protected tiger reserve and elephant reserve. There are an estimated 53 tigers (2010) in the reserve. The elephant number around 900 to 1000 individuals. Other mammals found here include gaur, Bison, sambar (horse deer), barking deer, mouse deer, Dholes (Indian wild dogs), mongoose, foxesand leopards. Also inhabiting the park, though rarely seen, are the elusive Nilgiri tahr. Four species of primates are found at Periyar - the rare lion-tailed macaque, the Nilgiri Langur, the commonlangur, and the Bonnet Macaque. According to a report by the Kerala Forest Research Institute, the protected area surrounding the dam and reservoir is classified as a biodiversity hot spot.
“States....must not wait for proof of harmful effects before taking action” (1984 Bermen Ministerial Declaration of the International Conference on the Protection of the North Sea)· “The parties should take precautionary measures to anticipate, prevent or minimize the causes of climate change and mitigate its adverse effects. Where there are threats of serious or irreversible damage, lack of full scientific certainty should not be used as a reason for postponing such measures” (1992 Framework for Convention of Climate Change, Art 3(3)).
Former Judge of Supreme Court Sri. V.R. Krishna Iyer, a great humanist, had invited the attention of the nation through an article in Hindu daily published in last year. In that article he pointed out that “Mullaperiyar is a classic instance where the precautionary principle of action cannot wait for a public calamity to happen. The nation as a whole must raise its voice against a possible natural calamity involving Mullaperiyar.”
He also cited a recent judgment of Supreme Court of India in M.C. Mehta v. Union of India (AIR 2004 SC 4033): “In such matters [involving actions that pose a threat of serious or irreversible damage], many a time the preferable option is not clear. If an activity is allowed to go ahead, there could be irreparable damage to the environment; if it is stopped, there could be irreparable damage to economic interests. In case of doubt, however, protection of environment should take precedence over economic interest. The Precautionary Principle requires anticipatory action to be taken to prevent harm. This harm can be prevented even on a reasonable suspicion. It is not always necessary that there should be direct evidence of harm to the environment.”
Nothing in life is entirely risk free, and indeed science cannot demonstrate freedom from risk, particularly from as yet known risks, because ‘absence of evidence’ is not ‘evidence of absence’! There are situations where engineers may disagree with one another. Some experts may consider the condition of a dam to be marginally safer than what others say it is. But nature has its own way, and experts’ expectations and calculations may go awry. Once there is reasonable apprehensions about the imminent danger and the possibility of a risk, the state should not take any chances.
Boyds Corner Dam is the first concrete dam built in USA in 1872. In 1980s, after the collapse of Tenton Dam, it was decided to review the condition of that dam. There was divided opinion on the safety of the dam. Some strongly believed that it was safe while others believed that it was unsafe. Despite opposition, the Government of USA decided to construct a new dam and the Boyds Dam was demolished and rebuilt in 1990.
Decommissioning of Old Victoria dam in Australia is an example of how a century old unsafe dam of almost the same age and built using similar technology as that of Mullaperiyar dam was treated in a developed country. This dam was constructed in 1891 with lime concrete like Mullaperiyar dam in 1895. In 1966, the Dam witnessed lot of seepages, which is also the case in Mullaperiyar dam. Certain strengthening measures were carried out to the Victoria dam, which were found to be inadequate in 1988. Therefore the authorities concerned decided to decommission the dam in April 1990. In its place, a new Victoria dam has already been constructed, which now supplies drinking water to the city of Perth.
The water bomb started ticking long back. The question is whether it is now or later. We have no time to debate. Act wisely. Use precautionary principles. Decommission the dam. It is pretty old. Let it retire. And construct the new dam as early as possible. And let the people down stream have a peaceful life.
1. James Wilson, Assistant Executive Engineer (Civil), Kerala State Electricity Board. (Presently working as a member of the Mullaperiyar Special Cell, Government of Kerala on deputation. Associated with Mullaperiyar case since 2006.)
2. Wikipedia
