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A group of international scientists studying China's Yellow river has come up with an analytic formula that could help officials better predict and prevent its all-too-frequent floods, which threaten as many as 80 million people.
The tool, a formula to calculate sediment transport, may also be applied to studying the sustainability of eroding coastlines worldwide.
"Understanding the flow of sediment in rivers is important to a large number of people around the world who live near these waterways," said Judy Skog, a program director for the National Science Foundation's (NSF) Coastal SEES (Science, Engineering and Education for Sustainability) program, which funded the research.
"This study will lead to better predictions of when and where rivers transport sediment, and to an understanding of how that sediment flow is affected by conservation and management efforts, such as the removal of dams," Skog noted.
Known in Chinese as the Huanghe, the Yellow river is considered the cradle of Chinese civilisation, and is often called the "mother of China" for its nutrient-rich sediment, which benefits farmland along its banks. But its floods, which led to some of the deadliest natural disasters in recorded history, have also earned it the name "China's sorrow."
Each of the river's identities, as the fertile nurturer and the wanton killer, derives from the same feature: the 1 billion tonnes of sediment that washes down each year from the Loess Plateau to the Bohai Sea. This huge sediment load can clog the river. When this happens, it not only floods but can change course.
"The Huanghe is probably the most studied fine-grained river in the world," said primary author Jeffrey Nittrouer.
"Despite that, the typical formulas and relationships that are used to describe sediment flux in most other rivers don't work for the Huanghe," Nittrouer noted. "They consistently under-predict the sediment load of the river by a factor of 20."
Nittrouer and lead paper author Hongbo Ma, also of Rice University, took sediment samples and created a 3-D map of the river bottom to create what they call a "universal sediment transport formula." The formula is the first physics-based sediment transport model capable of accurately describing how the Yellow river carries sediment, Nittrouer and Ma continued.
Ma said he hopes the new formula will prove useful to the Chinese engineers who manage the flow of water and sediment from dams along the Yellow river.
The study appears online in the journal Science Advances.
