Avulsion dynamics and experimental sedimentation (repost)

Sorry … this is another re-post … I am incredibly busy with final touches on the dissertation. My adviser is leaving to go out of the country very soon and I need to get his signature before then! It’s going to happen, but I still have some things to take care of. If you’ve been reading this blog for the last year, you’ve seen this before. But, if you are a relatively new to Clastic Detritus … read on!

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Last year, I discussed some work being done in experimental sedimentation. 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 was on their website several months ago…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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