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Avulsion dynamics and experimental sedimentation

May 20, 2007

Back in February during Just Science Week, I posted a bit about some of the work being done regarding experimental sedimentation (see here).

I highlighted the work being done by sedimentologists and dynamicists at the University of Minnesota’s St. Anthony Falls Lab in particular.

The video below is from some of their work…I encourage you to explore their data archive if you want to find more. This video shows a time lapse of sedimentation occuring on an experimental delta. This particular experiment nicely shows the dynamics of shifting pathways of sediment transport and/or deposition/erosion, otherwise known as avulsion. The deposit here would be more akin to a braided fan delta as it is not developing long-lived channels with cohesive levees.

The annotation shows where and when avulsion and expansion of channelized flow occurs. Also keep your eye on where deposition is occuring. This interplay of deposition and avulsion continues in a very dynamic (and seemingly unpredictable) fashion. Qualitatively, this isn’t really anything we haven’t known for a long time. The point with these experiments is that we can measure every last little detail. These researchers are really just scratching the surface — eventually they would like to try develop some fundamental quantitative relationships that might lead to predictive guidelines. But, it will take many years of experimentation to amass the data needed to converge on these relationships.

The photo below is shown on SAFL’s web page currently…it shows that they are now experimenting with systems that do produce cohesive levees, which is a key ingredient for understanding the dynamics of most river deltas.


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