News & Updates

Bakun Hep Reservoir Completes Two-Week Controlled Water Release To Raise Water Levels


15 JUNE 2022

Sarawak Energy’s two-week exercise to release water from the Bakun Hydroelectric Plant (HEP) reservoir to help with navigation and ensure adequate raw water source for water supply for the Rejang River communities has ceased on Monday (13 June 2022).

Sarawak Energy began the controlled release of water on 30 May 2022 to improve the low river water level situation and support downstream communities after the recent hot and dry spell experienced in Sarawak affected water levels along the Rejang River. The controlled release was done in collaboration with Sarawak Rivers Board and Sarawak Rural Water Supply Department (JBALB).

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

“Over drier weather, controlled release of water from our dam will help raise the water level. 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,” explained Ir. Bunyak Lunyong, Chief Executive Officer for SEB Power, the generation arm of Sarawak Energy.

Located upstream of the Rejang River, Bakun HEP and the Murum HEP form Malaysia’s only 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 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.

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. The released water also helps to maintain the ecology downstream vital for the ecosystem.

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 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% 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 a 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.

Before commencement of the controlled release from Bakun HEP: Low-water levels at downstream water treatment plant of the Rural Water Supply Department (JBALB)

Following the controlled release from Bakun HEP, downstream water levels improved to provide sufficient supply of raw water source to the water treatment plants.

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