For first time, meandering river created in laboratory

Sep 20, 2012

Natural rivers are not straight, and they are rarely idle. Instead, they bend and curve and sometimes appear to wriggle across the surface over time. That rivers can meander is obvious but how and why they do so is less well known. These questions are complicated by the fact that researchers have for the most part been unable to realistically create a meandering river in a laboratory. Scientists have previously created simulated streams that bend and branch, but they were not able to limit the river to only a single main flow path or maintain such dynamic motion past the initial bend formation. Working with a 6-by-11 meter (20-by-36 foot) river simulator called the Eurotank, van Dijk et al. created a dynamically meandering river. In so doing, the authors identify two conditions necessary to induce meandering: the availability of mixed sediment and a continuously varying upstream water source.

For 260 hours the authors pumped a steady stream of water and mixed onto a sediment-filled basin. First, they held the inflow point steady, which resulted in a straight channel. Then, they moved the inflow point horizontally, which caused the downstream flows to bend. Finally, the authors reversed the horizontal motion of the input point, which further increased the downstream complexity. Photographs taken every 10 minutes and high-resolution laser scans captured every 7 hours captured the details of the river's evolution.

The authors suggest that the drifting inflow point caused the channel to meander, while the presence of mixed sediments sealed off defunct paths, preventing the single channel from turning into a multithreaded braided system. The finding suggests that meandering at any point in a river depends on lateral drift in upstream reaches, such that an immobile bottleneck at any one site will decrease downstream complexity.

Explore further: Heavy metals and hydroelectricity

More information: Experimental meandering river with chute cutoffs, Journal of Geophysical Research-Earth Surface, doi:10.1029/2011JF002314 , 2012

add to favorites email to friend print save as pdf

Related Stories

Living, Meandering River Constructed

Sep 29, 2009

(PhysOrg.com) -- In a feat of reverse-engineering, Christian Braudrick of University of California at Berkeley and three coauthors have successfully built and maintained a scale model of a living meandering ...

Three Gorges Dam shrinking Yangtze delta

May 21, 2007

Chinese scientists have determined how China's Three Gorges Dam -- the world's largest dam -- affects downstream sediment delivery in the Yangtze River.

Syr Darya River Floodplain captured

Nov 02, 2010

Central Asia’s most important cotton-growing region is concentrated in the floodplain of the Syr Darya. The river was one of the farthest points reached by the ancient Greek leader Alexander of Macedon ...

Recommended for you

Australia launches 'Green Army' for environment

1 hour ago

Australia on Saturday launched its 'Green Army' which plans to recruit up to 15,000 young people for projects to conserve and rehabilitate the environment—the biggest land care mobilisation in the nation's ...

Tracking giant kelp from space

19 hours ago

Citizen scientists worldwide are invited to take part in marine ecology research, and they won't have to get their feet wet to do it. The Floating Forests project, an initiative spearheaded by scientists ...

Heavy metals and hydroelectricity

21 hours ago

Hydraulic engineering is increasingly relied on for hydroelectricity generation. However, redirecting stream flow can yield unintended consequences. In the August 2014 issue of GSA Today, Donald Rodbell of ...

What's wiping out the Caribbean corals?

21 hours ago

Here's what we know about white-band disease: It has already killed up to 95 percent of the Caribbean's reef-building elkhorn and staghorn corals, and it's caused by an infectious bacteria that seems to be ...

User comments : 0