The unexpected rise in the water level in the Idukki reservoir in the middle of October has been attributed to the change in the rainfall pattern in the past few years.
The dam was opened after 26 years on August 9, 2018 and by October the water level had started to decline. The water level in the dam on October 16, 2018 was 2,387 ft and 2,376 ft the same day last year.
As per the data available with the Dam Monitoring and Research Station, Vazhathoppe, the water level usually remains stagnant or increases at a minor level during October. The northeast monsoon usually does not make much of an impact in the dam water level with power generation remaining low.
Despite the increased power generation, the water level in the reservoir continued to rise, reaching 2,393.36 ft on Friday. If there is heavy rainfall within two days, there are chances of the dam being opened as it is short of only 5 ft to the dam opening level of 2,398.85 ft as per the new rule curve level.
The cumulative rainfall in the catchment area from June 1 to October 16 in 2018 was 4,468 mm, the highest ever since the commissioning of the dam in 1977. The cumulative rainfall till October 16 this year was 2,702 mm. The power generation has been raised to 9.34 mu now.
A Kerala State Electricity Board official said the board might look at the option of opening the dam shutters in case of heavy rainfall in two days. There were also chances of the water level remaining under control after the generation was increased and the rainfall declining.
In 2013, 2007, 1992, and 1981, the water level had remained higher than the present level as on October 16. The figures being 2,396 ft, 2,397 ft, 2,399 ft, and 2,399 ft respectively. The shutters of the Idukki reservoir were opened in 1992 and 1981.
The new rule curve is set by the Central Water Commission in consideration of the likely changes in the rainfall pattern. The water level should not be allowed above the rule curve level and the option of reducing the water level remains open, the official said.
