Authorities in the border province of Lao Cai expressed concern that the water level could rise to alarming levels.

China's Hekou Yao County announced recently that the Madushan Dam would open its floodgates from 9 a.m. to 5 p.m. Thursday as heavy rains had caused the dam to reach its maximum capacity, Vu Van Cai, director of the Department of Foreign Affairs of Lao Cai Province, said Thursday morning. He cited a communication to this effect from the Hekou Yao Department of Foreign Affairs.

The amount of water discharged has not been confirmed by Chinese authorities, Cai said.

"They did not provide a specific number, only saying that water levels in the Red River would be higher than what it was on August 18. This morning (Thursday), the water level in Lao Cai Town was 80.2 m," he added.

As of Thursday afternoon, a Chinese station about 80 km from the Vietnamese border observed the water level slowly rising, according to Vietnam’s National Center for Hydrometeorological Forecasting.

However, considering the dam's capacity to hold around 550 million m3 of water, the impact of the water discharge would not be too significant, said Tran Quang Hoai, deputy head of the Central Steering Committee for Natural Disaster Prevention.

Nevertheless, provincial authorities have requested districts and communes located along the river, including Lao Cai Town and the districts of Bao Thang and Bao Yen to stop fishing activities and waterway traffic, and to deploy flood prevention measures.

Other northern Vietnam localities, including the provinces of Yen Bai, Phu Tho and Vinh Phuc as well as the capital city of Hanoi should also closely monitor the situation to prevent flooding and landslides, evacuating vulnerable people if necessary, the Central Steering Committee for Natural Disaster Prevention said Thursday.

The Madushan Dam, in China's Yunnan Province, has a capacity of 300 MW and is about 350 km from Vietnam's border.

The Red River, over 1,100 km long, originates in China and runs through Lao Cai, Yen Bai, Phu Tho, Vinh Phuc and Hanoi. The river section that flows through Vietnam is about 510 km long.

Floods and landslides triggered by torrential rains in northern Vietnam have killed seven people and injured another four since August 17. The houses of around 1,000 families have been damaged and many households have been evacuated to safer ground.

Natural disasters, including drought, floods and landslides, killed 133 Vietnamese citizens last year and caused losses of around VND7 trillion ($302.6 million), according to the Ministry of Agriculture and Rural Development.

In the first half of this year, natural disasters including drought, flooding and landslides, killed 47 people and inflicted damages of VND3.3 trillion, according to official data.