Kerala's Idukki Dam gates to open after 26 years as heavy monsoon fills Periyar River; move will affect Idukki, Ernakulam, Kottayam

One of the highest arch dams in Asia, Kerala’s Idukki Dam is going to be opened for the first time in 26 years, owing to rising water level of the Periayar River following heavy monsoon rains in Kerala. On Monday night, the water level in the Idukki reservoir touched 2,395 feet against its maximum of 2,403 feet and just nine feet short of the full level, prompting the authorities to issue an orange alert in Idukki, Ernakulam and Kottayam districts.

A high-level meeting was conducted by chief minister Pinarayi Vijayan where it was decided that the dam would be opened when the water level reaches 2,400 feet. However, state power minister MM Mani had cautioned the Kerala State Electricity Board (KSEB) against waiting till the water level reached 2,400 feet and hence, it was decided to advance the opening of the dam.

The meeting, which was also presided by revenue minister E Chandrasekharan, water resources minister, Mathew T Thomas and revenue additional chief secretary, PH Kurian, was called to decide on the precautions to be taken once the shutters of the dam are opened.

File image of Kerala's Idukki Dam on the Periyar River. PTI

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The dam’s shutters were last opened in 1992. However, this is the first time that the dam will be attaining its full level during the South West Monsoon. The arch reservoir comprises of three dams built across the Periyar River — Idukki, Cheruthoni and Kulamavu. They were built for the Idukki Hydroelectric Project of the KSEB, but Idukki, being the highest, is used to store water while the other two are used to route it to the 780 MW powerhouse. The 550 foot high, double curvature dam is built between two granite hills — Kuravan and Kurinchi.

The shutters will be opened only in daylight and after sufficient notice is given to the public and all stakeholders concerned, a statement released by government authorities said. It added that there was no need for the public to panic and that the final red alert will be issued when the water level touches 2,399 feet. Earlier, the Kerala government had put the army, navy, air force and coast guard on alert to tackle any emergency situation.

Kerala State Electricity Board officials said that when the level reaches 2,397 feet, water might be released on a trial basis for one or two hours to find out the possibility of any obstructions or diversions on the route of water flow. The water will be released by opening the sluice gates of the Cheruthoni dam, which is built on the Cheruthoni river, a tributary of Periyar. The water will then merge with the main river.

"It was that we would open the shutters in a trial run first. However, if the water reaches 2,400 feet, we would be forced to open the shutters to reduce the levels. So, lessen the pressure we will first open the shutters in a controlled manner till the level reaches 2,400," Idukki Collector Jeevan Babu told The News Minute.

Idukki has received 192.3 cm of rainfall this year, which is 49% more than what the hill district received in 2017. According to the Kerala Disaster Management authorities, the gushing waters of Periyar could drown around 4,500 buildings along 100 metres of the river.

"A survey conducted by the authorities mentioned that buildings along 50 metres of the dam will be affected. The exact damage can be estimated once a proper ground study is done. As for the damage, not all parts of the river bank will be flooded. Except for the valley, most parts of the river are narrow and in certain flat regions, water may fill up. However, if we see that the water levels are rising more than desired, we can close the shutters. The exercise will be thoroughly monitored," the Collector said. He said that thee trial run would only be taken after reviewing the inflow of water to the dam and rain recieved in the catchment area and all steps have been taken to people's safety.

Meanwhile, chief minister Pinarayi Vijayan in a Facebook post on Monday said that a team of the National Disaster Response Force has already been deployed in Ernakulam and Thrissur and another team will reach Idukki soon as the state disaster management authority had taken all steps to tackle the situation if the reservoir shutters are opened. Four columns each of the navy and army are also ready for deployment if required, he wrote. Two helicopters have been kept ready. And the State Disaster Management Authority will give timely directive in this regard. The coast guard is also ready with small boats to evacuate people if water enters low-lying areas of Ernakulam, the chief minister said in his post.

As a precaution, people living downstream of the reservoir till Lower Periyar area in Ernakulam have been asked to be on vigil. But, as per The Indian Express' report, the State Disaster Management Authority member secretary Sekhar Kuriakose said that there was no need to panic as the dam shutters would only be opened 24 hours after declaring the red alert. However, restrictions have been imposed on tourists visiting areas near the dam.