Driftwood can be seen scattered besides the sluice gates of the Đắk Kar hydropower plant in the Central Highlands Province of Đắk Nông. Driftwood and rubbish brought on by the flooding last week are said to have caused the sluice gates to be jammed up, posing risks of dam burst. — VNA/VNS Photo

ĐẮK NÔNG — The concerning situation at Đắk Kar Hydropower Plant in the central highlands province of Đắk Nông has once again raised alarm on the safety of the region's many small and medium-sized hydropower plants during the rainy season, with experts warning immediate measures are needed to guarantee the safety of both people and crops.

On Thursday afternoon last week, an alarm went off at the plant's dam after its valve door was found to be jammed. Prolonged torrential rains have worsened the situation, and the dam was at heightened risk of bursting.

Around 5,000 people living in Bù Đăng District in Bình Phước Province, downstream from the plant, were evacuated. More than 300 households in Cát Tiên and Đạ Tẻh districts were at the ready and will be evacuated in case of an emergency.

Chu Văn Quyền, director of Đắk Kar Hydro-power JSC, told Thanh Niên (Young People) newspaper that the water volume had increased to more than 12 million cubic metres because of the heavy rains, far above the designed capacity of 11.6 million of cubic metres. Drifting pieces of wood jammed the reservoir's turbines.

By the weekend, rainfall had subsided and sluice gates were opened, dropping the water level by 2.5m.

However, the jammed valve door has still not been fixed.

Quyền said the company would fix the problem soon.

Meanwhile, chief secretariat of Đắk Nông Province’s Steering Committee for Disaster Prevention and Control Lê Viết Thuận said the plant’s investor failed to make a plan to deal with the daunting weather forecast.

Thuận also said the company's explanation for the damaged valve door was not satisfactory.

He said the valve door was eight metres high, and wood usually floats on the water surface instead of sinking to the level of the valve. He said it was possible the construction unit working to expand the valve had not completed its work.

Over the past few days, none of the stuck wood had been removed, he said.

Vulnerable downstream

Bùi Văn Hùng, chairman of the People's Committee of Cát Tiên District, said the district was adjacent to the plant, causing anxiety among residents.

“I have kept in touch with the plant’s director all the time during the heavy rainfall," he said. "Local authorities need to inform people about the situation so they can be ready in an emergency situation."

Lê Mậu Tuấn, vice chairman of the People's Committee of Đạ Tẻh District, agreed.

Lê Viết Thuận from the Đắk Nông Steering Committee for Disaster Prevention and Control said the weather forecast for the next five days indicated there would be between 50 and 100mm of torrential rains.

He said that if the rain did not let up, the committee would drill into the left side of the dam or use blasting mines to create a path for the reservoir to drain safely.

Võ Công Tuấn, head of the provincial Department of Industry and Trade’s Energy Management Unit, said the department is working with relevant units and investors to handle the situation.

He said the department would wait for the investor’s report and make its own assessment.

Trần Quang Hoài, director the ministry’s General Department of Disaster Prevention and Control, said three working delegations had been mobilised to ensure the worst does not happen.

The committee has requested local authorities and the project’s investor review and clarify the responsibilities of the units and individuals involved.

Unsafe reservoirs

Nguyễn Văn Tỉnh, director of the Ministry of Agriculture and Rural Development’s General Department of Irrigation, said there were more than 1,200 reservoirs in the region, and that many of that were at high risk of collapsing.

In Đắk Lắk alone, there were 605 reservoirs with a total capacity of about 650 million cubic metres, of which 404 were degraded.

Hoài, also chief secretariat of the Central Steering Committee for Natural Disaster Prevention and Control, said there were hundreds of small hydropower plants located along Vu Gia, Vu Bồn and Đồng Nai rivers in the central region.

In the Central Highlands area, small hydropower plants are located along Sê-san and Sê-rê-pốk rivers. Local authorities are responsible for approving and supervising the operation of these plants.

Reservoir owners are required to supply information about their water levels and supervise their safe discharge to protect the safety of people and crops in downstream areas.

Hoài said the reservoirs associated with small hydropower plants did not have flood prevention functions, so they must be monitored closely. The volume of discharge must not be larger than the flow of water into the reservoir, or else it could cause serious flooding downstream.

Hoài said the Central Steering Committee for Natural Disaster Prevention and Control has asked localities to strengthen the management of reservoirs to deal with the rainy season.

Localities have been required to reexamine and classify reservoirs and allocate funds to immediately repair any that are damaged. Forces must be mobilised around the clock to promptly detect problems at unsafe reservoirs and come up with timely solutions. — VNS