Mullaperiyar Dam: What Is Rule Curve That Decides On The Amount Of Water Releasing From Dam

Rule curve is a measure that specifies the storage or empty space maintained in a reservoir at different times of the year and the measure also decides on fluctuating storage levels of the reservoir. 

Chennai: The long-standing Mullaperiyar issue between Kerala and Tamil Nadu has been aggravated on November 1 when Kerala Water Resources Minister Roshy Augustine alleged that the Tamil Nadu government did not maintain the rule curve fixed by the Central Water Commission (CWC) in Mullaperiyar dam and the matter will be informed to Supreme Court and the committee. Soon, Tamil Nadu Water Resources Minister Duraimurugan said the water was maintained in the rule curve based on the guidelines of the Supreme Court.  

Duraimurugan also gave the same explanation to AIADMK and BJP who alleged that the DMK-led government surrendered to Kerala by reducing the level of water. 

What is a rule curve? 

Rule curve is a measure that specifies the storage or the empty space maintained in a reservoir at different times of the year and the measure also decides on the fluctuating storage levels of the reservoir. 

The rule of the curve is also the deciding factor on the opening of the gates of the reservoir. The rule curve is set by the Central Water Commission and during the monsoon, the number is fixed every 10 days once, based on the water level present.

However, recently, the Kerala government moved to SC to change the rule curve of Mullaperiyar Dam from 139.5 ft, the value that was fixed by the apex court earlier. For the plea last month, the SC told the Kerala and Tamil Nadu government to abide by the water level fixed by the committee in Mullaperiyar dam till November 10.

The case once again came up for hearing on November 9, when Kerala yet again sought SC to reconsider the rule curve adopted by the Tamil Nadu government by stating that no amount of rejuvenation can perpetuate the 126-year-old dam.