By Express News Service
KOCHI: The 126-year-old Mullaperiyar dam, which is a composite gravity dam (combination of concrete and embankment), is in a deteriorating condition due to age and it should be decommissioned to enable the construction of a new dam, Kerala submitted before the Supreme Court in a written note on Thursday.
“The consequences of any failure of the dam could be extremely catastrophic and beyond human imagination. The apprehensions of the Kerala government regarding the life and safety of more than 30 lakh people in 5 districts residing downstream of the dam have to be given due importance and consideration”, Kerala submitted in the note.
The state has opposed the view of the Supervisory Committee constituted by the Supreme Court that the dam would hold 142 feet of water level. The Supervisory Committee and Tamil Nadu maintain that there is no danger or threat to the dam. The Committee recommended before the Supreme Court on Wednesday that there is no need to change the water level in the dam.
Kerala meanwhile added that the hearting (material used as fill) of the dam which accounts for more than 60 percent of the volume of the dam was constructed with lime surkhi concrete. Quite understandably, seismic forces were not considered in its design. In spite of the strengthening measures taken twice, the dam is in a deteriorating condition. There would be an exponential increase in water pressure and uplift pressure acting on the dam when the water level is raised from 136 feet to 142 feet.
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The catchment area of Mullaperiyar reservoir is 624 sq km. The gross storage capacity is only 12.758 TMC ft at 142 feet. Mullaperiyar, therefore, is exceptionally vulnerable because it has a large catchment area and limited storage capacity. Consequently, the water level in the Mullaperiyar dam increases rapidly compared to Idukki which has a catchment area of 650 sq km and a storage capacity of 70.5 TMC ft.
Kerala sought to keep the water level in Mullaperiyar at 139 feet as Idukki reservoir is nearing full reservoir level and any sudden large release from the upstream dam can worsen the situation, forcing to make large releases from Idukki causing flood in downstream areas.
Kerala pointed out that Tamil Nadu was not utilizing the full outflow capacity of the Mullaperiyar dam. At 137 feet, the full outflow possible is 2,735 cusecs but Tamil Nadu was drawing only 2,200 cusecs. Which was increased to 2,300 cusecs as the water level reached 137.8 feet.
Kerala pointed out that Tamil Nadu can create additional storage facilities at appropriate places in Tamil Nadu and enhance the capacity of the Vaigai dam to store water drawn from Mullaperiyar. The capacity of the existing tunnel can be enhanced or an additional tunnel can be constructed for drawing more water, which will help to keep the reservoir level at a safer level without reducing water viability as suggested by an empowered committee constituted by Supreme Court in February 18, 2010.
Kerala does not demand a reduction of water used by Tamil Nadu. In fact, Kerala is requesting to use more water by adopting appropriate measures, Kerala’s standing counsel G Prakash said in the note.
Meanwhile, Tamil Nadu has agreed to open the shutters and release water from the dam from 7 am on Friday.
Though located in Kerala, the dam is operated and maintained by Tamil Nadu.