Mullaperiyar Dam

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Context

• Tamil Nadu reversed its plan to open the Mullaperiyar dam's spillway shutters following a pause in rainfall and a decrease in the dam's water intake.

About Mullaperiyar Dam

• It is a masonry gravity dam located in Kerala's Thekkady, Idukki district, on the Periyar River.
• It is situated on the Cardamom Hills of the Western Ghats, 881 metres above sea level.
• At the meeting point of the Mullayar and Periyar rivers is where the dam is situated.
• Its building was finished in 1895, having started in 1887. Under Pennycuick's direction, the British Corps of Royal Engineers completed the building.
• Limestone and "Surkhi" (burnt brick powder and a concoction of sugar and calcium oxide) were used to build the dam.
• The dam was built to redirect the waters of the west-flowing River Periyar eastward, into the dry areas that receive rain shadows in the Tamil Nadu districts of Theni, Madurai, Sivaganga, and Ramanathapuram.
• The reservoir of the dam is surrounded by the Periyar National Park.
• The nearby state of Tamil Nadu is in charge of running and maintaining the dam, despite its location in Kerala.
• The operating rights were given to Tamil Nadu in accordance with a 999-year lease arrangement negotiated during British control.

Dispute between Kerala and the Tamil Nadu States:

• Kerala has questioned the legitimacy of the 1886 lease agreement and has attacked it.
• But since 2009, there has been discussion about the risk that Keralans would face if the 126-year-old dam failed.
• Kerala has proposed to demolish the dam and construct a new one, a move that Tamil Nadu has opposed.
• Tamil Nadu has criticised Kerala for its tardiness in completing the rule curve for the dam.
• The different storage levels in a reservoir inside a dam are determined by the rule curve. As a component of the dam's safety system, the rule curve controls when the dam gate opens.
• The purpose of the rule curve level is to prevent the emergency dam shutter from opening in the case of a flood-like scenario.
• It assists in controlling the water level of the Mullaperiyar dam during the monsoon season. Kerala has often attempted to stop Tamil Nadu from operating the dam since Tamil Nadu is unable to acquire data due to Kerala's topography.
• Despite Tamil Nadu's payment, there is no road and the electricity supply has not been restored.
• Tamil Nadu has been charged by Kerala of operating gates in 1939 with a "outdated" schedule.