In China, people sometimes refer to the Yellow River as the River of Sorrow or the Scourge of the Sons of Han. The river is Asia's second-longest and is infamous for its unpredictable and oftentimes devastating floods. However, scholars also believe that it was the birthplace of Chinese civilization, proving the resources that culture needed to flourish.
Now, evidence has emerged that for nearly as long as humans have been taking advantage of the Yellow River's resources, they have also been altering its natural course. Beginning around 3,000 years ago, researchers found, people living along the Yellow River started building levees and other flood mitigation systems. As populations increased, alterations to the river became more and more extreme.
The team arrived at this conclusion after analyzing 50 feet of soil layers from an archeological site, which radiocarbon dating confirmed represents about 10,000 years of history. They found the that the sediment deposition rate had increased—a tell-tale sign of human expansion in the area, which causes erosion—and also analyzed the soil for chemical signatures indicative of major changes in the area.
By 2,000 years ago, they report, the river had been altered so much that it hardly resembled the natural system of 1,000 years before. "It's easy to see the trap they fell into: building levees causes sediments to accumulate in the river bed, raising the river higher, and making it more vulnerable to flooding, which requires you to build the levee higher, which causes the sediments to accumulate, and the process repeats itself," the researchers say in a statement. "The Yellow River has been an engineered river — entirely unnatural — for quite a long time."
The river, however, was far from tame. A massive flood around AD 14 cost the lives of approximately 9.5 million people, the researchers say, and seemed to have marked the beginning of the end for the Western Han Dynasty. Devastating Yellow River floods continued to be the norm throughout Chinese history, and today, massive dams and dykes occur along the river to try to contain it.
"To think that we can avoid similar catastrophe today due to better technology is a dangerous notion," the researchers say. "Unlike ancient China, where human mistakes devastated a single river valley, we now have the technology to make mistakes that can cause devastation on a truly global scale."