Cheruthoni: What will happen to lower Periyar if the shutters of the Cheruthoni dam are lifted? Nothing serious, going by a statement from the Kerala State Electricity Board (KSEB) that owns and maintains the half-century-old Idukki hydel power project.
It is easy to claim that the upstream water will pass through the five sluice gates of the lower Periyar dam once it reaches there.
Authorities recalled that lower Periyar, which also houses the project’s hydropower station, has had its dam built with the intention of executing such an action when there is a need — like the one now – underscoring the point that there won't be undue hazards in executing the plan.
Lower Periyar is so placed geographically that it is set to receive a huge volume of water. The dam is raised at such a point that it can check the waters from Idukki and Cheruthoni reservoirs, besides the water from Neriamangalam electricity project. The lower Periyar dam is at Pambla, five kilometres downstream from where Muthirapuzha merges with the main river. This 31-metre-high reservoir made of concrete has a width of 241 meters. The powerhouse is at Karimanal, near Neriamangalam, where authorities have installed three generators with a power production capacity of 60 MW each, or a cumulative 180 MW.
A tunnel channels the water from lower Periyar dam to the powerhouse.
High time for dredging
The water level at the reservoir is regulated by raising its shutters at the start of the annual rainy season.
Right now the second sluice gate is up to let out the excess water flowing into the dam. That being the case, opening the Idukki reservoir upstream would mean influx of loads of water to lower Periyar, leading to a possible overflow. What is more, the latter’s sluice gates will have to grapple with not just the water, but the boulders, wooden logs and the sand the deluge would bring down to lower Periyar. They can cause obstructions to the smooth flow of water, effectively weakening the whole hydel project. Even the powerhouse faces such a danger.
