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New Approach to Understanding Sediment Transport in River Channels

A recent set of four related articles published in the Journal of Geophysical Research-Earth Surface takes a new approach to understanding sediment transport, a vital component to the ecological health and long-term evolution of river channels.

When you look at a river’s water surface, it is rarely smooth. Instead, you can usually see the continual churning of turbulent river flow. Sediment transport occurs as this turbulent flow disturbs sand and gravel riverbeds, and the river is flowing fast enough to move the particles downstream. The complex nature of turbulent river flow makes quantifying sediment transport a difficult task.

The new approach to understanding sediment transport developed in this study involves describing individual sediment particle motions and positions as the basis for calculating total transport amounts. High-speed videos of sand grains moving at different flow rates were analyzed to provide experimental data to compare with the new theory. A video showing digitized sand grains transported during experiments is available here. The transport of sand particles is shown by experiment results to be extremely variable in both the location and amount of sediment movement at any given flow. This variability in particle motions results from the complex interaction of turbulent flow with the riverbed.

As our understanding of sediment transport and other river processes continues to improve, so does the ability of the restoration community to provide effective, science-based solutions to degraded aquatic resources, increasing the likelihood of long-term success of restoration projects.

Author John Roseberry, an Environmental Engineer at Trout Headwaters, Inc. and Ph.D. candidate at Vanderbilt University, was lead author of the second article in the series of four from this study. 

Links:

Roseberry et al, 2012: http://www.agu.org/pubs/crossref/2012/2012JF002353.shtml

Furbish et al, 2012a:  http://www.agu.org/pubs/crossref/2012/2012JF002352.shtml

 

Water Law: U.S. Supreme Court Reinvigorates Public Trust Doctrine, Clarifies Possession of Missouri River Bottomland

The 16-kilometer (10-mile) stretch of the Missouri River where it passes Great Falls,Montana, was once so swift, roiling, and precipitous that, in 1805, the Lewis and Clark expedition spent 11 days hauling equipment and boats on an overland portage to continue their transcontinental journey.

Earlier this year, the same fast-flowing reach again came to national attention, when the United States Supreme Court unanimously clarified the ownership of the riverbed beneath the Missouri and two other Montana rivers, the Madison and the Clark Fork.

In February’s 9-to-0 ruling — which overturned a previous decision by the Montana Supreme Court from March 2010 — the high court also asserted, emphatically, that states have the authority to protect the public’s use and enjoyment of rivers, regardless of who owns the bottom. In doing so, the U.S. Supreme Court confirmed a state’s authority to implement and enforce river safeguards to prevent interference with public use and environmental harms.

What might, at first glance, appear to be a loss for Montana has actually set a precedent to protect water as a public trust in the United States during an age when water is increasingly being viewed as a commodity.

Read more of this special to the Circle of Blue by James Olson:
http://www.circleofblue.org/waternews/2012/world/water-law-u-s-supreme-court-navigates-waters-of-ownership-clarifies-possession-of-missouri-river-bottomland/?utm_source=Circle+of+Blue+WaterNews+%26+Alerts&utm_campaign=cd1e9776c5-Weekly_Water_News_May_2_20125_2_2012&utm_medium=email