Nghe An: Ban Ve Hydroelectric Reservoir experienced an exceptionally large flood

This is an exceptionally large flood, exceeding the test flood frequency (the test flood of Ban Ve hydropower project has a flow rate of 10,500 m3/s).

According to Power Generation Corporation 1 (EVNGENCO1), due to the impact of storm No. 3, an exceptionally large flood occurred in the reservoir basin of Ban Ve Hydropower Plant.

The flood started at 4:00 a.m. on July 22 with a flow rate of 583 m3/s, the lake water level at the same time was 189.08 m. The flood then increased rapidly, reaching 1,500 m3/s at 10:00 a.m. the same day, the lake water level was 189.69 m.

Faced with that situation, at 10:15 a.m. the same day, Ban Ve Hydropower Company received an order to operate flood reduction for the downstream from the Steering Committee for Natural Disaster Prevention, Search and Rescue and Civil Defense of Nghe An province.

At 4:00 p.m., the reservoir began operating to regulate water through the spillway with a flow rate of 508 m3/s (valve gates fully open), the total water discharge through the project was 845 m3/s, the water level of the reservoir at the same time was 191.23 m (the lowest flood level was 191.5 m).

At 2:00 a.m. on July 23, the flood in the lake reached its peak with a flow of 12,800 m3/s. At the time of the flood peak, the Ban Ve Hydropower Reservoir discharged 3,285 m3/s of water through the project, reducing the flood peak flow by 74%.

Flood cutting and reduction for downstream causes the lake water level to increase rapidly, gradually shifting the lake to operating mode to ensure construction safety.

However, due to serious flooding in the downstream area, Ban Ve Hydropower Company has reported to the Chairman of Nghe An Provincial People's Committee to request a change from the operation mode to ensure project safety to the abnormal operation mode to limit water discharge downstream, continuing to contribute to reducing flooding in the downstream area.

This is an exceptionally large flood, exceeding the frequency of flood checks (the flood check of Ban Ve Hydropower Plant has a flow rate of 10,500 m3/s). However, the company has operated to ensure absolute safety for the headworks, contributing significantly to cutting and reducing floods downstream./.