Water level in Ban Ve hydroelectric reservoir drops to unprecedented low

Mr. Ta Huu Hung - Director of Ban Ve Hydropower Company said that the capacity of Ban Ve reservoir is more than 1.8 billion m^3,in which the useful capacity from elevation 155m - 200m is 1.3 billion m³water.

However, the current water level of the lake is only 159.25m, 19m lower than the same period. This water level is only 4m higher than the dead water level and the remaining useful capacity is only over 90 million m³.

Water level was measured at 4:36 p.m. on June 2 at Ban Ve Hydropower Reservoir. Photo: TDBV

Since the beginning of the year, due to the influence of El Nino, the water flow to Ban Ve reservoir has been very low, with a water frequency of over 90%; meanwhile, the demand for water supply downstream is very large, so from the beginning of the year, to ensure productivity for the winter-spring crop, Nghe An Provincial People's Committee has requested Ban Ve Hydropower Plant to release water 3 times, especially at the end of April, when thousands of hectares of winter-spring rice enter the flowering period and require large amounts of water.

Water flow chart to regulate drought prevention for downstream from January 1 to May 31, 2023. Photo: TDBV

On June 2, 2023, the People's Committee of Nghe An province continued to direct to serve water supply for people to sow summer-autumn crops, requesting Ban Ve Hydropower Plant to supply water with a flow of 200m³/s in the first 8 days of June. To avoid wasting water, it is recommended that downstream localities and people actively take water to ensure the right season.

Operational information at Ban Ve Hydropower Plant. Photo: TDBV

"With the current extreme weather, if Ban Ve Hydropower Reservoir continues to release water according to the direction of the Provincial People's Committee, after about 6-8 days, Ban Ve Hydropower Reservoir will return to dead water level," said Mr. Hung.

When the reservoir reaches the dead water level of 155m, the Ban Ve Hydropower Plant is only allowed to generate electricity with the discharge flow equal to the return flow. According to regulations, only in special cases due to the need to meet energy security can the reservoir below the dead water level be continued to be exploited. Therefore, in the second half of June and the end of the dry season, if the weather continues to be extremely hot, the downstream of the Ca River will experience a shortage of water supply to the downstream and the risk of not being able to supply enough electricity to the system.

Chart of total water volume regulated to combat drought downstream in the dry season. Photo: TDBV

“Towards the end of the dry season when heat waves occur over a large area, the demand for water in the downstream increases, so the water level in the lake gets lower and lower. Currently, the measured amount of water flowing into the lake is an average of 35m³/second, compared to this time in 2022 is 105m³/second. In the hot season in early June this year, the water level of Ban Ve hydropower plant was at its lowest since the plant began operating," Mr. Hung worried.

Also according to Mr. Hung, in previous years only 150m2 of water was needed to be discharged.³/second, all pumping stations along Lam River are operating. This year, the main branches of Lam River such as Nam Mo River and Hieu River are also severely drought-prone, so Ban Ve Hydropower Plant has to increase discharge by 200m.³/second new pumping stations get water for agriculture.