Bakun HEP.

KUCHING: Hydropower dams such as Bakun Hydroelectric Plant (HEP) mitigate the impact of heavy rainfall within upstream catchments by storing water in the reservoir, reducing the severity of floods in areas downstream.

Recent studies conducted by third party consultants have shown that Bakun HEP has regulated the flow rates in the downstream regions by half.

For Bakun HEP, owned and operated by Sarawak Energy, reservoir levels are managed by releasing water at regulated volumes through the gated spillway.

In a statement yesterday, Sarawak Energy said that this controlled procedure was conducted on a seasonal basis after permission was secured from the Sarawak Rivers Board and the communities were notified at least three days ahead of the scheduled release.  

“This is standard practice for hydropower operators worldwide and has been undertaken by the operator of Bakun since it was commissioned in 2010,” it said.

SEB said that the current seasonal release of water through the Bakun HEP spillway had commenced on May 3 and was scheduled to last for three weeks, until the water level normalises.

“Over this period, the release volume is kept as low as possible, balancing both the upstream reservoir and downstream river levels and will cease once the water level in the reservoir normalises.

“The rise in river level and intensity of flowing water will reduce as the distance increases. Areas furthest downstream of the dam will experience a generally imperceptible rise in river level,” it said.

Sarawak Energy said the released water was estimated to flow past Kapit town about one day later and Sibu town after three days.

It noted that the main contributors to flood situations were natural factors such as heavy rainfall at downstream regions, high sea tides for coastal areas, and water flowing from tributaries of the Rajang River.

“Spilling by itself does not cause a flood situation, due to the managed volumes.

“On top of flood mitigation, the dam also holds back river debris within the catchment, making downstream navigation much safer,” it added.