One man had predicted the Banqiao disaster. Chen Xing, a hydrologist involved in the project, was concerned that the dam would dangerously raise the water tables and lead to disaster. He was roundly dismissed as a “right-wing opportunist” by the Communist Chinese government. Had they listened, hundreds of thousands of lives could have been saved.

The rains began on August 5, 1975. A typhoon was making its way through Henan province in eastern China, and the downpour was so cataclysmic that witnesses reported the ground was strewn with dead birds pelted to death by the force of the falling water. The rainfall from that one day exceeded the yearly average. The next day, it poured for another 16 hours. The day after that, for 13 more. The nearby Banqiao dam, which crossed the powerful Ru River, was designed to handle a half meter of rainfall over three days. It had rained six times that much.

Because of flooding further down the valley, workers had been ordered not to release too much water from the Banqiao dam. But after the first day, communication lines went down, so the workers were forced to guess what they should do. In the nighttime darkness on August 8, a line of people moved frantically through waist-deep water to pile sandbags on top of the dam. It was still pouring. In the villages below, millions were sleeping. Shortly after midnight, the water rose just over a foot above the dam’s crest. Then the water appeared to retreat. The storm clouds cleared. The night sky shone with stars. There was silence. "The flood is retreating!" they shouted. Moments later, they heard a terrible noise. It “sounded like the sky was collapsing and the earth was cracking," a survivor said. An older woman looked up from her work and yelled, “The river dragon has come!”

The equivalent of nearly 300,000 Olympic swimming pools burst through the dam. A wall of water nearly 20 feet high and over seven miles wide surged through the villages below. Banqiao’s bursting set off a domino effect, sending water rushing through dozens of dams downstream. By the time the night was over, 62 dams had burst and 26,000 people drowned. Some managed to survive by climbing trees or gathering on roofs. But in the coming days, many of those who initially survived met a much slower death. They were stranded without food or clean water. Food was airdropped but was lost in the water or spoiled in the scorching summer heat. People tried to survive by eating floating animal carcases. Disease spread quickly. In total, the death toll would swell to between 171,000 and 230,000, making it the worst energy disaster, and what some have called the worst structural failure, in history.

And it was all preventable.

The breach in the Banqiao dam unleashed a tremendous amount of water onto unsuspecting towns and villages. (Wikimedia)

The Banqiao dam was built in 1952 when the government sought to “harness the Huai river” after a series of floods in the Huai River Basin. Flooding had always plagued that region, and now the republic would transform potential tragedy into a literal source of power. Over a hundred dams were constructed all over the Chinese plains during this period. In 1955, after some flaws were discovered in the Banqiao dam, it was reinforced with the help of the Soviets and called “the iron dam.” It was said the dam could not be broken. In his book Heaven Cracks, Earth Shakes, James Palmer characterized the dam-building effort as an example of “Maoist arrogance” where leaders were “determined to prove that man could conquer nature.”

During the planning, Chen Xing repeatedly raised red flags. When he suggested twelve sluices for drainage, the number was whittled down to five. Finally, he was removed from the project and sent away to another city. He was only brought back once problems emerged in 1961 and then again after disaster. As he sat next to party officials and surveyed the devastated, flooded landscape from above in an aerial tour, he must have felt a helpless rage. He was vindicated, but this was the cost. After the tour, he headed to Beijing to lobby for explosives to clear the blocked channels.

The natural question becomes why, considering that this was one of the worst structural failures in all of history, is this disaster lesser known than Chernobyl, Bhopal, or Fukushima? The event is little known even in China. As Eric Fish noted in the Economic Observer, the disaster “occurred in an era when the state quickly covered the scale of such catastrophes.” He also comments that 30 years later, few discuss it even as China is undergoing another round of rapid dam building.

Though the flooding caused the dam to break, Human Rights Watch characterizes the event largely as a man-made disaster because of the government’s errors in the original construction and the lack of transparency. But the disaster has alarming implications for today. Dam safety is determined as much by the amount of water that can pass through a dam as by how much a dam can hold back. But as Fish warns, climate change has skewed those calculations: “What were once considered freak weather occurrences are transitioning to routine events.” This gives rise to the question: which dams won’t hold up?