KUCHING: Sarawak Energy Bhd (SEB) is implementing a water management system to better manage water resources at the reservoirs of its hydropower plants.

According to the state-owned utility corporation, the system is currently being adopted at its hydroelectricity power plants (HEPs) in Batang Ai, Murum and Bakun, to manage the interplay between weather, water flows and water release requirements.

“The dynamic water dispatch management system integrates data on weather and inflow forecasts to optimise the operations of SEB’s HEPs, especially in a cascading scheme such as the plants in Bakun and Murum.

“The Murum HEP is located upstream of Bakun HEP – the water released from Murum would arrive at the Bakun reservoir, generating energy for the second time through Bakun turbines,” it said in a statement.

SEB said with the adoption of the management system, water released from these plants could be modelled, incorporating predictive weather patterns and providing more accurate inflows and forecasted reservoir levels up to six months or more.

“This would enable us operate and run our HEPs more efficiently.

“With better prediction of inflows and reservoir water levels, a controlled release could be better planned during drier season, providing better water level management upstream and downstream.

“Once the system is fully operational, the HEPs could mitigate the impact of heavy rainfall, reducing the severity of floods for areas downstream,” said the corporation.

SEB added that it would commence its seasonal controlled release from the Bakun reservoir this Dec 23, which would run for five weeks until the water level in the reservoir had normalised.

“Over this period, the release volume is kept as low as possible, balancing both the upstream reservoir and downstream river levels to minimise the impact to the downstream regions.

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

“For instance, the released water is estimated to flow past Kapit town about one day later, and Sibu town after three days,” it said.

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

“Controlled release by itself does not cause a flood situation, due to the managed volumes,” it added.

Owned and operated by SEB, Bakun HEP has a water storage capacity of 40 billion cubic metres.

Studies conducted by third-party consultants have shown that Bakun HEP holds back 30 per cent of water flow from upstream tributaries of the Rajang River, and regulates downstream flood rate by half – greatly reducing flooding over the downstream areas of Belaga, Kapit and Sibu.

“When the Bakun reservoir level exceeds a certain point, water is released at regulated volumes through its spillway, specially designed for this purpose.

“This controlled release is conducted on seasonal basis after permission is secured from the Sarawak Rivers Board, and the communities would be notified at least two days ahead of the scheduled release.

“This is a standard practice for hydropower operators worldwide, which has been undertaken by the operator of Bakun (dam) since it was commissioned in 2010,” said SEB.