River ‘piracy’ drains one of China’s largest rivers

River ‘piracy’ drains one of China’s largest rivers

Over the past 1.7 million years, China’s Yangtze River has stolen water from the Yellow River, new study finds

By Jackie Flynn Mogensen edited by Claire Cameron

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One of China’s two main rivers “pirates” water from the other, according to new search. Over the past 1.7 million years, the Yangtze River has stolen water from the Yellow River, and this theft could dangerously worsen the water level of the Yellow River.

THE Yangtze And YELLOW The rivers are among the longest in the world. They stretch thousands of kilometers across China and supply water to hundreds of millions of people. And now, researchers estimate, the Yellow River has lost on average, over the long term, about five billion square meters of water to the Yangtze each year. The results, published last week in the Geophysical Research Journal: Earth Surface, add critical insight to China’s plans to fight water shortage caused by climate change and human overexploitation of the Yellow River. In other words, to reshape a river, one must understand the ancient forces already acting on it.

If you were to float down the Yangtze, you would see steep gorges. But if you went down the Yellow River, the Yangtze’s sister river to the north, you would see a more gradually sloping topography. These geographical differences reflect a long-standing tug-of-war between the two rivers for water over millions of years – and the Yangtze appears to be the clear winner.

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Using a combination of field observations and modeling, the researchers tracked several climate-driven “capture events” — when one river diverts water from another, essentially — between the Yangtze and the Yellow Rivers 1.7 million to 0.8 million years ago. The water captured by the Yangtze is so large that it forces the migration of a 3,000-kilometer-long divide between the sources of the two rivers, the researchers write in the study.

The geological war over water could have profound implications for populations who rely on the Yellow River for their water. China plans to divert some four billion cubic meters of water from the Yangtze to the Yellow River each year in the first phase of part of the project. South to North Water Diversion Project– but it is less water than what is captured by the Yangtze, warn the authors of the study.

“This highlights a profound mismatch between the time scales of landscape evolution and water resource engineering,” the researchers write.