Madushan dam in China opened its floodgates for eight hours on August 20, prompting Vietnam's northern localities, including the capital city of Hanoi, to take precautions for flooding, according to Vietnam's National Steering Committee of Natural Disaster Prevention.

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

According to the Department of Foreign Affairs of Lao Cai province, China’s Madushan dam opened its floodgates from 9am to 5pm last Thursday as heavy rains filled the dam to its maximum capacity.

The specific amount of water discharged has not been confirmed by Chinese authorities, the department said, adding that China’s Madushan dam released water following days of torrential rain caused by Higos storm.

Madushan dam in China. Photo: Internet

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.

The release raised the water level of the Red river in the northern province of Lao Cai by 0.88 meters to 80.55 meters at 5:00 am on Friday, the center said.

However, considering the dam's capacity to hold around 550 million cubic meters of water, the impact of the water discharge would not be too significant, the National Steering Committee of Natural Disaster Prevention said.

Nevertheless, the committee has requested provinces of Lao Cai, Yen Bai, Phu Tho, Vinh Phuc and the capital city of Hanoi to closely monitor the situation to prevent flooding and landslides and evacuating vulnerable the areas if necessary.

Tuoi Tre Online on August 21 quoted Nguyen Duc Quang, director of the Agency for Disaster Response and Relief (ADRR) under the Vietnamese Ministry of Agriculture and Rural Development as saying that the water discharged by the Chinese hydropower dam will not likely have much impact on Vietnam.

“It is forecast that in the coming weeks, such discharge will repeat due to complicated rain and flood situations,” Quang said.

China and Vietnam have no formal treaty on sharing information regarding dam discharges, the official noted, adding that alerts for any changes in the river’s water level are currently provided by five monitoring stations near the Vietnam-China border three times a day.

“We learn whether the Chinese side has discharged water from its dams or not basing on information from these five monitoring stations,” Quang said.

He stressed that if the parties involved could be more open in sharing their water discharge plans, Vietnam would be more proactive in disaster response.

Madushan dam, in China's Yunnan province, is about 350 kilometers from Vietnam's border.

The Red river, of over 1,100km 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 510km long.