Natural disasters are tragedies that usually strike randomly and infrequently – unless you happen to live in the Huang He River (colonially referred to as the Yellow River) valley in China. In the space of just over 50 years between 1887 and 1943, some 10 million people drowned or died of famine and disease as the result of catastrophic floods.

While particularly deadly, those floods were nothing new to the Huang He. Since 600 BC, the Chinese have recorded over 1,500 floods, earning it the name “China’s Sorrow.” Across the world there are rivers with valleys more populous, the Yangtze for instance. And there are those that flood more often, like the Nile. And there are rivers that carry far more water than the Huang He, such as the Amazon. So why is the Huang He so deadly?

At the headwaters of the Huang He lies a vast plateau of loose material called loess, blown in from the Gobi Desert. The loess erodes relatively easily, especially when carelessly farmed, and strong rains wash that loess into the river. This unique combination of geography and geology makes the Huang He the most sediment-laden river in the world. A thousand miles away the river flattens out and slows. There, most of the sediment settles to the river bed, raising it by an inch or two each year.

In an ultimately futile attempt to control the river, the Chinese built levees along the river’s banks. But to keep up with the rising bed, the levees had to constantly be built higher. As the centuries passed, the river bed rose above the level of the surrounding plains, and so did the levees.

In some places, the bottom of the river bed stood as much as 10 meters above the surrounding floodplain. The Huang He was literally suspended in the sky.

So stood the Huang He when in 1887, record spring rains and melting snow forced it overtop its 60 foot high levees. Water flowing down the backs of the levees quickly eroded them and allowed the entire river, at that point over a mile wide, out onto the floodplain. This inundation killed tens of thousands of people, and crop failures from flooded farms killed as many as a million more.

This disaster would stand as the deadliest non-pestilential disaster in recorded history were it not for another flood just 44 years later. In 1931, the Huang He claimed between 850,000 and 4 million lives in what still stands as the worst natural disaster in recorded history.

But the river wasn’t done; just two years later another severe flood killed 20,000. And in 1938, Chinese Nationalist forces intentionally blew up the levees in order to stop the advance of Japanese troops. The river again inundated massive parts of north-eastern China and slowed the advance of the Japanese. While debatably militarily successful (a stalemate was reached in the north of China by 1940), this single act killed another million Chinese citizens through famine. And cruelly, no longer confined to a channel, the river again flooded in 1943 and killed millions more.

Its bloodlust apparently satiated, the Huang He has remained fitfully within its artificial banks since the end of World War II. In 1956, A Soviet-designed dam was constructed at Sanmenxia in the first modern engineering attempt to tame the mighty river. But the Soviet designers had little experience with high sediment loads, and realizing their failure they withdrew before the project was complete. Less than 3 years after its completion, the Sanmenxia reservoir had nearly entirely filled with sediment. Today the now-useless Sanmexia dam stands quiet, its sediment-choked turbines long since removed.

For much of the year, the modern Huang He river does not even reach its mouth. Thousands of miles of dikes, diversion channels, dams, and irrigation canals sap the river’s strength. But heavy rains or a particularly warm spring can spell danger, as in 1958 when the Huang He’s flow doubled literally overnight. Millions of Chinese laborers were mobilized to watch the levees for leaks and pile on sandbags. The river rose within inches of flooding before it receded.

The next Huang He flood may be just months away, or it may lay quiet for centuries. But what is certain is that the river has the power to overwhelm the devices humans have built to control it.

Unfortunately the risk of catastrophic flood has never been higher. Since the end of World War II, the Chinese population has doubled and enormous new metropolises have sprung up along the banks of the Huang He. In 1996, the level of the river reached an all-time high despite river flow being much lower than it was in 1958. Were widespread flooding to occur, there is nothing that could be done to stop it from inundating much of north-eastern China. We can only hope that the sprawling cities above which China’s Sorrow literally stands suspended in the sky can be evacuated in time.