Idukki reservoir opened for first time after 2018

Vinson Kurian Thiruvananthapuram | Updated on October 19, 2021

File picture of the Idukki reservoir   -  The Hindu

Two shutters at Idamalayar, Pampa lifted earlier

Three warning sirens went off from 10.50 am this (Tuesday) morning before dam operating authorities lifted the first of the three shutters of the Cheruthoni dam flanking the main Idukki arch dam and its massive reservoir.

Two more of the five shutters at Cheruthoni (the main Idukki dam does not have any) will be opened by 35 cm in due course to release water impounded at a height of 2398.08 ft (maximum permissible level is 2403 ft).

Water thus released is expected to reach the main towns of Kalady (85 km away) and Aluva (92 km) by 4 pm, according to sources.

People downstream shifted

Earlier in the morning, authorities shifted more than 200 members of 64 families in downstream areas of the reservoir, largest in Kerala, in preparation of opening of the shutters following rain in the catchment area.

It is for the first time since the Great Floods of 2018, and fifth in history, that owner and operator Kerala State Electricity Board (KSEB) will resort to letting go some of its ‘carefully guarded and invaluable resource’ from the hydel project, KSEB Chairman B Ashok said.

Estimated revenue loss

The power utility estimates that lifting of one shutter by 50 cm will lead to a loss of ₹1,875 per second in revenue it would have generated if the same had been harnessed to generate hydel power which the massive project has been been set up for.

This would translate into a revenue loss of ₹67,50,000 in an hour, and more than ₹2 crore if three of the five shutters are lifted for the same duration. One ft of water drained from the reservoir will set the reservoir back by 850 cubic ft and the KSEB by ₹14 crore in revenue in three hours which is what it takes to lift one shutter by 50 cm and close it down.

2018 precedent

During the 2018 Great Floods, all five shutters were opened in phases and kept in that position for 30 days, releasing as much as half of the reservoir content totalling to an estimated 1063.25 million cu ft, equivalent to 1,500 mu of generated power. It would have been sufficient to fuel the state’s power requirement for 23 days.

Also see: Water level in dams rising in Kerala

Three years down the line, a wiser KSEB is seeking to trim any such loss in storage and revenue by timing the releases in advance and in a controlled manner. It wants to make sure that it would not be required to act in one fell swoop and incur what to its mind is an ‘an eminently preventable drawdown of its precious resources’.

Idamalayar, Pampa opened

Earlier on Tuesday morning, authorities opened two shutters each of the Idamalayar and Pamba reservoirs, two other large ones in the state, as rains broke out in the catchment areas just as in the case of Idukki ahead of the arrival of the North-East monsoon.

This came to happen only the morning after parts of the body of the 29 persons who perished in some of the most violent floods and landslide witnessed since 2018, even rivalling it in some cases, in the scenic rural outback of Kottayam district.

Two shutters of the Pampa reservoir were lifted by 30 cm each while those of Idamalayar by 80 cm after people downstream were served mandatory warning of a rise of of up to 10 cm in River Pampa and up to a metre in River Periyar into which the water empties.

Published on October 19, 2021

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