Idukki and Mullaperiyar dam shutters opened again

This is the second time that the shutters of Mullaperiyar dam were opened within a year while the shutters of Idukki dam were opened thrice this season.

Water being released from Mullaperiyar dam. (File photo| EPS)

IDUKKI: With isolated heavy rainfall set to continue over Idukki till Friday, the shutters of the Idukki and Mullaperiyar reservoirs were opened on Thursday to let out surplus water.

This marked a rare instance when the shutters of the reservoirs were opened for more than once in a year. This is the second time that the shutters of Mullaperiyar dam were opened within a year while the shutters of Idukki dam were opened thrice this season.

The public works department of Tamil Nadu initially released 772 cusecs (cubic feet per second) of water from Mullaperiyar dam by opening two (V3 and V4) of its 13 shutters at 8 am after the water level in the dam touched 141 ft against the permissible level of 142 ft at 6 am on Thursday.

By 10 am, the discharge was increased to 1,544 cusecs in addition to the 2,300 cusecs water released via penstocks. Meanwhile, the water level recorded in the Idukki dam was 2399.44 ft with the storage remaining stable at 95 percent.

However, considering the possibility of water level in the dam surging further when the discharged water from the Mullaperiyar dam reaches the Idukki reservoir, shutter number 3 of Cheruthony dam was lifted up to a height of 40 cm at 10 am to release 40 cumecs of water.

Inflow doubles

Owing to the night-long heavy rain in the catchment areas of both the dams, the inflow had doubled on Wednesday night. While Idukki recorded 36.8 mm rainfall, the catchment areas of Mullaperiyar dam – Periyar and Thekkady – recorded 15.4 mm and 19.6 mm rainfall respectively.

The inflow of water into Mullaperiyar had doubled 6,050-metre cusecs, which was only 2,300 cusecs till Wednesday evening. The inflow of water into the Idukki reservoir on  Thursday was 16.147 million cubic metres.

“The Idukki reservoir is already at 95% of its capacity, and surplus water had to be let out. A flood warning has been issued in areas downstream of the dam
and along banks of river Periyar,” said an official.

The shutters of Idukki dam were first opened on October 19 after water level in the dam crossed 2,398 ft. The shutters were closed later on October 27 when the water level came down to 2,397 ft. However, due to heavy rainfall in the catchment areas and the water level surging above the red alert level of 2,399 ft, one shutter of the dam was opened again on Sunday (November 14). After keeping it opened for two days, the shutters were closed on Tuesday at night.

Although shutters of Mullaperiyar dam were also opened same time on October 29, Tamil Nadu closed the dam shutters on November 6.