Idukki dam opened to attenuate flood woes

A shutter of the Cheruthoni Dam, one of the three dams of Kerala’s giant Idukki hydel reservoir system, was opened on Thursday for the first time in the past 26 years for what the authorities called a “trial run” after water level soared above 2,399 feet following heavy inflow from catchment areas due to incessant rains. The reservoir’s maximum storage level is 2,403 feet.

The Kerala State Electricity Board (KSEB) lifted the middle gate of the five-shutter block of the Cheruthoni dam at 12.30 hrs Thursday by 50 cm to release 50 cubic meters of water per second into the Cheruthoni river which joins River Periyar one kilometer downstream. The KSEB had been preparing to lift the shutter for the past several days.

Though the KSEB and Power Minister MM Mani had said on Thursday morning that the gate was being opened as part of a four-hour trial run, it was not closed after that duration. The shutter might remain open throughout Thursday night and there was every possibility of the board opening more shutters on Friday as the water level was climbing steadily.

The volume of water flowing into the reservoir on Thursday evening was said to have been five times greater than that being drawn for power generation and released through the single gate. Instead of dropping, the water level reportedly soared to 2,399.90 at 8.00 PM Thursday from the level of 2,399.04 feet at the time of the start of the trial run.

Despite the authorities’ warning to people not to go near a 100-meter limit from the river-line, hundreds had gathered on the banks of the Cheruthoni river to witness the spectacle of water gushing down from the gate. “People had come from even other districts to see the opening of the shutter,” said a policeman at Cheruthoni town.

Dam shutters of the Idukki hydel project had been opened four times in the past: Twice in 1981 and twice in 1992. This is for the first time that a dam shutter is being opened during the June-September southwestern monsoon season. The Cheruthoni dam shutters were opened in 1981 and in 1992 during the October-December northeastern monsoon.

The reservoir of the 780-MW (130 MW X 6 generators) installed capacity Idukki hydel project, completed in 1975 and commissioned the following year, has a surface area of over 60 square kilometers and is constituted by three dams: The Idukki dam, said to be the largest arch dam in Asia and the Cheruthoni and Kulamavu dams.