About Mullaperiyar Dam Dispute

Context:

Tamil Nadu cancelled the decision to open the spillway shutters of Mullaperiyar dam recently after a lull in rainfall and a reduced inflow of water to the dam.

Relevance:

GS-II: Polity and Constitution (Interstate water disputes), GS-I: Geography (Water Sources), GS-III: Disaster management

Dimensions of the Article:

1. About Mullaperiyar Dam
2. About the Dispute regarding Mullaperiyar river
3. Background on Dams in India
4. Ageing dams in India: Highlights of the UN Report
5. Issues with Ageing Dams in India
6. Way Forward

About Mullaperiyar Dam

• The Mullaperiyar Dam is a masonry gravity dam on the Periyar River in Kerala – built at the confluence of Mullayar and Periyar rivers.
• It is located on the Cardamom Hills of the Western Ghats and it was constructed between 1887 and 1895 (by John Pennycuick).
• The Periyar National Park in Thekkady is located around the dam’s reservoir.
• The catchment area of the Mullaperiyar Dam itself lies entirely in Kerala and it is argued that it is not an inter-State river, however, by the principle of estoppel (new argument cannot be against previous action/agreemet/statement) it is considered otherwise.

About the Dispute regarding Mullaperiyar river

• The dam is located in Kerala on the river Periyar, but is operated and maintained by the neighbouring state of Tamil Nadu.
• For Tamil Nadu, the Mullaperiyar dam acts as a lifeline for Theni, Madurai, Sivaganga, Dindigul and Ramnad districts, providing water for irrigation and drinking, and also for the generation of power in Lower Periyaru Power Station.
• While Kerala has pointed out the unfairness in the 1886 lease agreement and has challenged its validity, Tamil Nadu has insisted on exercising the unfettered colonial rights to control the dam and its waters, based on the 1886 lease agreement.
• There is also the issue of concerns regarding the ageing Mullaperiyar dam (including alleged leaks and cracks in the structure) have been repeatedly raised by the Kerala Government while the Tamil Nadu governments have sought to downplay these concerns.
• While Tamil Nadu has sought to increase the limit of maximum water level in the dam to 152 ft, Kerala has strongly argued against such a move citing safety concerns.
• Kerala’s proposal for decommissioning the dam and constructing a new one has been challenged by Tamil Nadu.

Rule of Curve issue

• A rule curve or rule level specifies the storage or empty space to be maintained in a reservoir during different times of the year.
• It decides the fluctuating storage levels in a reservoir.
• The gate opening schedule of a dam is based on the rule curve. It is part of the “core safety” mechanism in a dam.
• The TN government often blames Kerala for delaying the finalization of the rule curve.

Background on Dams in India

• India has 4,407 large dams, the third highest number in the world after China (23,841) and the USA (9,263).
• India is ranked third in the world in terms of building large dams.
• Tehri Dam in Uttarakhand is the highest dam in India built on Bhagirathi River.
• Hirakud Dam in Odisha built on river Mahanadi is the longest dam of India.
• Kallanai Dam in Tamil Nadu is the oldest dam of India. It is built on the Kaveri River and is about 2000 years old.

Ageing dams in India: Highlights of the UN Report

• India is ranked third in the world in terms of building large dams.
• Over a thousand large dams in India will be roughly 50-years-old in 2025 and such aging structures pose a growing threat.
• There are also more than four thousand large dams in the country that will be over 50-years-old in 2050 and 64 large dams will be more than 150-years-old in 2050.
• Ageing signs include increasing cases of dam failures, progressively increasing costs of dam repair and maintenance, increasing reservoir sedimentation, and loss of a dam’s functionality and effectiveness, “strongly interconnected” manifestations
• Krishna Raja Sagar dam was built in 1931 and is now 90 years old.
• Mettur dam was constructed in 1934 and is now 87 years old.
• The report said that approximately 3.5 million people are at risk if India’s Mullaperiyar dam in Kerala, built over 100 years ago, “were to fail”.

Issues with Ageing Dams in India

• As dams age, soil replaces the water in the reservoirs. Therefore, the storage capacity cannot be claimed to be the same as it was in the 1900s and 1950s.
• Studies show that the design of many of India’s reservoirs is flawed in the sense that the designs underestimate the rate of siltation and overestimate live storage capacity created.
• When soil replaces the water in reservoirs, supply gets choked. The cropped area begins receiving less and less water as time progresses.
• The net sown water area either shrinks in size or depends on rains or groundwater, which is overexploited.
• The designed flood cushions within several reservoirs across many river basins may have already depleted substantially due to which floods have become more frequent downstream of dams.

Way Forward

• Assuring the safety of the downstream population should be the topmost priority in this scenario. The remaining works to strengthen the Mullaperiyar dam are to be done at the earliest.
• There is a need to assure Kerala that all the instruments for monitoring the safety and health of the dam are installed and are functioning properly.
• As there are sufficient scientific and technological tools to respond effectively to any legitimate and genuine concern, every stakeholder should adopt a rational approach while deciding on the storage levels and safety aspects of the dam.

-Source: The Hindu