Central Idea

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

Do you know?

The Mullaperiyar dam is located in Kerala on the river Periyar but is operated and maintained by the neighbouring state of Tamil Nadu.

John Pennycuick (the architect of this dam) sold his family property in England to mobilize money to fund the project! People of the region fondly name their children under his name a remark of reverence.

Mullaperiyar Dam

• It is a masonry gravity dam on the Periyar River in Kerala.
• It is located on the Cardamom Hills of the Western Ghats in Thekkady, Idukki District.
• It was constructed between 1887 and 1895 by John Pennycuick (who was born in Pune) and also reached in an agreement to divert water eastwards to the Madras Presidency area.
• It has a height of 53.6 m (176 ft) from the foundation, and a length of 365.7 m (1,200 ft).

Operational issue

• The dam is located in Kerala but is operated and maintained by Tamil Nadu.
• The catchment area of the Mullaperiyar Dam itself lies entirely in Kerala and thus not an inter-State river.
• In November 2014, the water level hit 142 feet for first time in 35 years.
• The reservoir again hit the maximum limit of 142 feet in August 2018, following incessant rains in the state of Kerala.
• Indeed, the tendency to store water to almost the full level of reservoirs is becoming a norm among water managers across States.

Dispute: Control and safety of the dam

• Supreme court judgment came in February 2006, has allowed Tamil Nadu to raise the level of the dam to 152 ft (46 m) after strengthening it.
• Responding to it, the Mullaperiyar dam was declared an ‘endangered’ scheduled dam by the Kerala Government under the disputed Kerala Irrigation and Water Conservation (Amendment) Act, 2006.
• For Tamil Nadu, the Mullaperiyar dam and the diverted Periyar waters act as a lifeline for Theni, Madurai, Sivaganga, Dindigul and Ramnad districts.
• Tamil Nadu has insisted on exercising the unfettered colonial rights to control the dam and its waters, based on the 1886 lease agreement.

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.

Back2Basics: Periyar River

• The Periyar is the longest river in the state of Kerala with a length of 244 km.
• It is also known as ‘Lifeline of Kerala’ as it is one of the few perennial rivers in the state.
• It originates from Sivagiri hills of Western Ghats and flows through the Periyar National Park.
• The main tributaries of Periyar are Muthirapuzha, Mullayar, Cheruthoni, Perinjankutti.

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