Decommission Mullaperiyar Dam: Kerala has objected to the Supreme Court-appointed Supervisory Committee’s conclusion that the dam could store 142 feet of water.
KOCHI: The 126-year-old Mullaperiyar dam, a composite gravity dam (concrete and embankment), is degrading owing to age and should be decommissioned to allow for the construction of a new dam, according to officials. Kerala filed a written note with the Supreme Court on Thursday.
“Any failure of the dam might have devastating implications that are beyond human comprehension.” The Kerala government’s concerns about the lives and safety of more than 30 lakh people in five districts living downstream of the dam must be given due weight and consideration, according to the note.
The state has argued against the Supreme Court-appointed Supervisory Committee’s conclusion that the dam could contain 142 feet of water. The dam is not in any danger, according to the Supervisory Committee and Tamil Nadu. The Committee recommended before the Supreme Court on Wednesday that the dam’s water level should not be changed.
Meanwhile, Kerala stated that lime surkhi concrete was utilised to construct the dam’s hearting (material used as fill), which contributes for more than 60% of the dam’s capacity. Seismic forces, naturally, were not factored into the design. Despite the fact that the dam has been strengthened twice, its condition is deteriorating. When the water level is raised from 136 feet to 142 feet, the water pressure and uplift pressure pushing on the dam will increase exponentially.
Mullaperiyar reservoir has a catchment area of 624 square kilometres. At 142 feet, the gross storage capacity is only 12.758 TMC ft. As a result of its enormous catchment area and limited storage capacity, Mullaperiyar is particularly vulnerable. As a result, when compared to Idukki, which has a catchment area of 650 sq km and a storage capacity of 70.5 TMC feet, the water level in the Mullaperiyar dam rises quickly.
Kerala aimed to limit the water level in Mullaperiyar at 139 feet since the Idukki reservoir is approaching full capacity, and any significant release from the upstream dam could exacerbate the situation, requiring large releases from Idukki and triggering flooding in downstream districts.
Tamil Nadu was not using the Mullaperiyar dam’s full outflow capacity, according to Kerala. The maximum outflow possible at 137 feet is 2,735 cusecs, however Tamil Nadu was only pulling 2,200 cusecs. When the water level reached 137.8 feet, it was increased to 2,300 cusecs.
Kerala suggested that Tamil Nadu build more storage facilities in appropriate locations and expand the capacity of the Vaigai dam to hold water taken from Mullaperiyar. As stated by an empowered committee convened by the Supreme Court on February 18, 2010, the capacity of the existing tunnel can be increased, or a second tunnel can be built to take more water, which will help to keep the reservoir level at a safer level without diminishing water viability.
Kerala does not insist that Tamil Nadu reduce its water consumption. Kerala, in reality, is demanding additional water by taking adequate precautions, according to Kerala’s standing counsel G Prakash.
In the meantime, Tamil Nadu has agreed to open the dam’s shutters and release water starting at 7 a.m. on Friday.
The dam is operated and maintained by Tamil Nadu, despite its being in Kerala.
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Kerala notifies the Supreme Court that a new dam must be built to end the threat to lives in Mullaperiyar.
Decommission Mullaperiyar Dam: According to the report, a cascade failure of Mullaperiyar and Idukki will result in a disaster.
The Kerala government made a powerful case in the Supreme Court to decommission the 126-year-old “deteriorated” Mullaperiyar dam, which is operated by Tamil Nadu, and replace it with a new one, claiming that climate change, erratic and heavy rainfall, and floods make the threat of disaster real and imminent.
Kerala’s affidavit is timed to coincide with a red alert issued in Chennai as a result of heavy rainfall. The rains in Chennai followed several days of heavy rain in Kerala.
The State also mentioned the Uttarakhand flood of February 2021, also known as the Chamoli disaster, which was mostly caused by climate change in the Nanda Devi National Park, a UNESCO world heritage site.
In an affidavit, the State, represented by advocate G. Prakash, stated, “The only permanent solution for removing the eternal threat posed by the 126-year-old existing dam in Mullaperiyar and for protecting the safety of the lakhs of people living downstream of Mullaperiyar dam is to build a new dam in the downstream reaches of the existing Mullaperiyar dam.”
The idea was first proposed in 1979. In talks with the Union Minister for Water Resources and the Chief Ministers of Kerala and Tamil Nadu, Kerala proposed it. “However, Tamil Nadu had not agreed to the new dam project,” the document stated.
Decommissioning of the Victoria Dam
The State cited the deactivation of another 19th-century lime concrete facility, Australia’s Victoria dam, which was decommissioned due to seepages.
“In April 1990, authorities decided to decommission the dam. A new Victoria dam has been built in its stead, providing drinking water to the city of Perth,” Kerala explained.
The State asked the court to have the Supervisory Committee review the 142-foot upper rule level set by Tamil Nadu in collaboration with the Central Water Commission as the peak value (CWC).
It was believed that if the water level at Mullaperiyar was kept higher, releases from it would harm the already full Idukki reservoir.
“A cascading failure of Mullaperiyar and Idukki will cause an unimaginable disaster, endangering the lives and property of 50 lakh people living below the Idukki dam,” Kerala said.
In the Seismic Zone III area
It said that the ageing dam was located in Seismic Zone III and requested the court to order Tamil Nadu to create a “complete instrumentation strategy” for the dam.
The State maintained that it provided a detailed presentation to the Supervisory Committee on October 25 on the “tremendous” change in the “dynamics” and “pattern” of rainfall after the State’s 2018 floods.
In light of the Northeast monsoon, Kerala did not agree with Tamil Nadu’s proposed rule curve and insisted on keeping the water level in the reservoir at 137 feet.
“The Tamil Nadu government has been repeatedly asked to take the necessary steps to raise the discharge through the spillways and tunnel in order to keep the water level at the rule level. Though Tamil Nadu officials increased the spillway discharge, their efforts did not result in the reservoir level remaining at 138 feet on October 31, 2021, and the water level remained at 138.55 at 11 p.m. on October 31, 2021, which was above the upper rule level proposed by Tamil Nadu and thus violated the Supreme Court’s directions,” Kerala claimed.
On October 28, the court issued an interim order requiring the States to follow the water level set by the Supervisory Committee.
On November 11, the case will be heard by a Bench led by Justice A.M. Khanwilkar.