Silt fills almost half the storage in Kerala’s Malankara dam causing capacity crisis
Nearly half of the storage capacity of the Malankara dam in Idukki, part of the Muvattupuzha Valley Irrigation Project (MVIP), is filled with silt, severely
Nearly half of the storage capacity of the Malankara dam in Idukki, part of the Muvattupuzha Valley Irrigation Project (MVIP), is filled with silt, severely reducing its volume. The full reservoir level of the dam is 42 m. According to officials, a 2021 study conducted by the Kerala Engineering Research Institute (KERI) found that silt occupied 48.95% of the reservoir’s total storage capacity. Due to this reduced capacity, MVIP officials are facing a serious crisis in managing water storage and preventing flooding in the Thodupuzha and Muvattupuzha rivers. “The Malankara dam primarily stores tailrace water released from the Moolamattom powerhouse after electricity generation at the Idukki reservoir.
With the Malankara shutters wide open, this water flows directly downstream into the Thodupuzha river and then to the Muvattupuzha river,” said an MVIP official. Power generation “The tailrace water and two other streams constitute themajor inflows into the dam. During heavy rains, the inflow from the streams to the dam becomes uncontrollable, leading to excess water. However, if water levels in the Thodupuzha and Muvattupuzha rivers are at dangerous levels owing to the rain, releasing more water from the dam can cause severe flooding. To prevent this, we have been requesting the Kerala State Electricity Board (KSEB) to stop or reduce power generation at the Moolamattom plant to limit the arrival of tailrace water,” the official said.
“In the recent floods,the KSEB supported us by keeping power generation at a very low level, which restricted the massive inflow of tailrace water and helped avoid flooding. However, when there is high power demand, we cannot ask the KSEB to reduce or stop power generation,” the official added. The official further noted that, based on the KERI study, a decision was made to desilt the Malankara dam. “As per the project plan, silt will be cleared to a depth along an eight-kilometre stretch upstream from the dam to the Kanjar bridge. The project is expected to be completed within three years, and the contracting company will pay for the sand extracted from the reservoir,” the official said.
Clearing the silt will restore the reservoir to a safe storage capacity level. To manage crisis “Presently, fiveshutters of the dam are open. In recent days, these shutters have been raised and lowered to various levels to manage the low storage capacity and prevent flooding,” the official said. According to the officials, the Malankara dam functions as a diversion dam, and its inflow depends primarily on the KSEB’s power generation at the Moolamattom powerhouse. Consequently, the dam does not operate under a strict rule curve.
The BriefWire