The Three Gorges Dam experienced a flood crest, the largest since it began storing water, between Tuesday night and early Wednesday, but flood control authorities promised the dam was safe.
The dam, the world's largest hydropower project, saw its biggest flood this year as water from the Yangtze River's upper reaches gushed at 71,200 cubic metres per second into the dam's reservoir at 8 pm on Tuesday, raising the water level to nearly 160 metres, according to China Three Gorges Corp.
The peak water level in the dam's reservoir increased from 157.34 metres at 2 pm, when water flow through it reached 70,000 cu m per second, it said.
In a major effort to reduce flooding on the lower reaches of the Yangtze River, water was released at a rate of 43,000 cu m per second on Tuesday afternoon, it said.
The dam began to store water in 2003, when the maximum water level in its reservoir was 135 metres, and it became fully operational in 2010, when the maximum level increased to 175 metres.
In 2010, a great flood hit the Three Gorges Dam, raising the water level in the reservoir to 161.01 metres, according to the Changjiang (Yangtze River) Water Resources Commission.
The current flood crest represents the biggest challenge the dam has faced, but it poses no threat to the safety of the dam, Zhao Yunfa, deputy director of the China Three Gorges Corp's cascade dispatch center, told China Daily.
"In preparation for the surging flows of water, the dam has increased its water release from 38,000 cu m per second to 43,000 cu m per second since Saturday, leaving sufficient room to store water," he said.
Boat traffic in the area has been suspended. All of the Three Gorges' ship locks were closed on Monday night, forcing more than 700 vessels to drop anchor, the Changjiang (Yangtze River) Water Resources Commission said at a news conference on Tuesday.
The latest flood crest came after heavy rains hit upstream areas of the Yangtze River beginning on Friday.
Steady rains caused water levels in several rivers in the upper reaches of the Yangtze River to exceed warning levels, and the Cuntan section witnessed the most flooding since 1981, the State Flood Control and Drought Relief Headquarters said on Tuesday.
By Tuesday, downpours had forced the evacuation of about 216,000 residents in Sichuan and Chongqing, it said.
The flood peak hit 11 districts of Southwest China's Chongqing municipality on Tuesday, causing a direct economic loss of 710 million yuan (S$140 million), according to a statement from the municipal flood control and drought relief headquarters.
The flood peak is the largest experienced by the main urban area of the municipality since 1981, according to the flood control authority.
The flood submerged riverside roads and restaurants in the municipality's Yuzhong district, which is located close to the downtown area.
Although authorities issued alerts to local residents and business owners before the flood, the flood peak still caught many off guard.
"It has been many years since the water rose this high," said Zeng Kaicheng, who runs an automobile-repair plant beside the Yangtze River in the Yuzhong district.
Zeng said authorities alerted him in advance, but he thought the floodwater would not affect him.
By around 8 pm on Monday, Zeng realized the flood was larger than normal, but it was already too late. He loaded some household appliances into his car and left. By 9 pm, floodwaters had submerged his plant.
The sidewalks along the river in Yuzhong district were packed with desks, chairs and cooking utensils from riverside hotpot restaurants, the roofs of which were barely visible.
On Tuesday, tens of thousands of people flocked to Chaotianmen Square, where the Yangtze River and the Jialing River converge, for a view of the flood peak in the Yangtze River.