Bakun HEP reservoir completes 2-week controlled water release to raise water levels

Water release from the 2,400MW Bakun Hydroelectric Plant during spillway gate checking in 2020.

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KUCHING, June 15: Sarawak Energy Berhad’s (Sarawak Energy) two-week exercise to release water from the Bakun Hydroelectric Plant (HEP) reservoir ceased on Monday (June 13).

According to a press statement, Sarawak Energy began the controlled release of water on May 30 to improve the low river water level situation and support downstream communities after the recent hot and dry spell experienced in Sarawak which affected the water levels along Rejang River.

The controlled release was done in collaboration with Sarawak Rivers Board (SRB) and the Sarawak Rural Water Supply Department (JBALB).

Over the two-week period, low water levels downstream of the Bakun dam have improved allowing better river navigation and sufficient volume at water treatment plants for the Gawai Dayak festival.

Sarawak Energy generation arm SEB Power chief executive officer Ir Bunyak Lunyong said the controlled release of water from the dam will help raise water levels over dried weather.

“During extremely rainy weather, our dams hold back water upstream of Rejang. This has lessened the severity of floods downstream for Belaga, Kapit, Sibu and its surrounding areas,” he said in the statement today.

Located upstream of the Rejang River, Bakun HEP and Murum HEP form Malaysia’s oniy cascading dam system. In addition to renewable energy generation, both plants are operated synergistically to allow better water and flood management and control.

“Dedicated teams at our hydroelectric plants monitor water levels at the reservoir and downstream rivers daily and will advise if there is a need for controlled release. This is done in consultation with and with permission from the Sarawak Rivers Board.

“Throughout our hydropower journey, we have witnessed the positive impact of hydropower in generating reliable electricity supply, catalysing growth, supporting social development and water management,” Bunyak added.

Low-water levels at the downstream water treatment plant before commencement of the controlled release from Bakun HEP.
Following the controlled release from Bakun HEP, downstream water levels improved to provide sufficient supply of raw water source to the water treatment plants.

Fulfilling its role in facilitating water management beyond just electricity generation, the 2,400MW Bakun HEP provides water security for downstream usage by balancing upstream and downstream flow.

In efforts to improve the accuracy of incoming flood warnings and to enhance the efficiency of Sarawak Energy’s hydroelectric plants’ operation, a digital system for weather forecast, inflow forecast and dynamic dispatch management was introduced in 2020.

The system enables the prediction of inflow levels more accurately which in turn helps determine the volume for release for better water level management upstream and downstream.

The system is currently being adopted at Sarawak Energy’s three HEPs of Batang Ai, Murum and Bakun to manage the interplay between weather, water flows and water release requirements.

Bakun HEP has a water storage capacity of 40 billion cubic meters, and holds back 30 per cent of water flow from upstream tributaries of the Rejang River and regulates downstream flood rate by half, greatly reducing flooding situations in the downstream areas of Belaga, Kapit and Sibu.

Controlled release from reservoirs is standard practice for hydropower operators worldwide to mitigate floods or to improve low water levels downstream. This has been undertaken by the operator of Bakun since it was commissioned in 2011. — DayakDaily