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Video shows devastating impact if China's Three Gorges Dam collapses

Video estimates collapse of dam would release 100-meter wall of water racing at 100 kph

(Twitter, @caijinglengyan image)

(Twitter, @caijinglengyan image)

TAIPEI (Taiwan News) — A video showing the consequences of a catastrophic failure of the Three Gorges Dam has quickly gone viral on social media.

According to Chinese government statistics, 45.2 million people have been affected by the floods that have ravaged 27 provinces along the Yangtze River, Huai River, and Yellow River, as well as southern China since the start of June. Many have cast doubt on the integrity of the Three Gorges Dam as it faces the greatest test in its history, while others have questioned the structure's purported purpose of flood control, given the extensive flooding recently seen both above and below the dam.

On Tuesday, the Chinese financial news site Caijing Lengyan released a controversial video that simulates the devastating flooding that would occur if the vaunted Three Gorges Dam collapsed. The video shows the path the wall of water might take and includes estimates on the speed, depth, and reach of the floodwaters all the way to Wuhan.

The video starts out by stating the height of the Three Gorges Dam is 181 meters above sea level, its length is 2,355 meters, and the normal reservoir level is 175 meters with a capacity of 39.3 km3. Ominously, the words "once the dam breaks" appear as the animated video shows the dam disintegrate under heavy pressure from floodwaters.

The video segment then issues the disclaimer: "The data in the following video are estimates and not for actual reference." The video then states that after the dam breaks, a wall of water with a height of nearly 100 meters would be rapidly discharged.

Due to the presence of steep mountains on both banks of the river, the flood cannot be dispersed. The video estimates the speed of the flood at this stage will exceed 100 kilometers per hour.

As the distance from Three Gorges Dam to the downstream city of Yichang is only 50 kilometers, the video predicts that within 30 minutes after the dam breaks, Gezhouba Dam will be crushed and the city of Yichang destroyed. A flood surge 20 meters in height would strike Yichang at a speed of 70 kph and bury it under 10 m of water.

In the simulation, after the flood passes through Yichang, it continues to move along the Yangtze River, submerging towns along the way at a speed of at least 60 kph. The height of the flood at this stage is about 15-20 m.

After inundating Yidu, the flood gushes out of the mountain valleys and into the open plains. The flood begins to spread across the region in a fan-like pattern, greatly increasing the area affected.

As the flood is dispersed across the plains, the height will be reduced to about 8 meters and a speed of 25 kph. However, the flood in the main channel of the Yangtze River will still maintain a velocity of 35 kph.

The flood then reaches the city of Jingzhou, and part of the flood will break off from the main channel and head straight for Wuhan. Within five hours after the collapse of the Three Gorges Dam, the flood is predicted to hammer the city of Yueyang, which is 350 km downstream.

The simulation predicts that Yueyang will be inundated by 5 m of floodwaters. However, it states that nearby Donging Lake could act as a buffer and alleviate some of the flooding, if the collapse does not occur during flood season.

Next, the flood is predicted to head east and be further diminished after it hits Hong Lake, which is 700 km from the dam. The video then predicts that 10 hours after the mammoth dam collapses, the city of Wuhan will bear the brunt of the flood.

It is estimated that when the floodwaters arrive in Wuhan they will be 7 m in height. Although some urban areas of the city on high ground will be spared, other parts will be submerged under 5 m of floodwaters.

Due to the narrow width of the Yangtze River channel in Wuhan, it is predicted the flood will be slow to leave the city, and pools of water that have formed will not easily subside.