Thursday, April 26, 2012

Thurs-Demo: The One that goes with the flow

This week, we're mixing the slow and the fast. Our Em2 stream table is an amazing model. I think it's the best fluvial system-in-a-box models out there and I wish that everyone who do outreach/education/research about streams and the environment had one. I understand that these things aren't cheap and if there's one thing most environmental educators are familiar with, it's lack of spare dollars. Which is why I appreciate the "open source" approach that Steve and the LRRD team bring with their stream tables. A fully equipped Emriver model may cost a few thousand dollars, but the knowledge the LRRD has gained from the model development is priceless.

With that knowledge comes a willingness to share and collaborate. I even hear they're looking into ways of sharing more than just expertise (but I don't want to spill their beans - if Steve wants to provide more information, go ask him about it). I don't want to sound like I'm trying to sell you a stream table. But I do want you to think about how you can use the ideas generated by these stream tables. If anything, I'm trying to sell you on the idea that stream tables can be more than just sand in a watertight box with an aquarium pump.

Okay, back to my demo. Over the last semester, I tried taking time-lapse photographs of the stream table in order to show some long-term process over a shorter time span. Recently, our department acquired another amazing tool - a high-speed camera. It takes thousands of frames of video every second and expands a very short-term process into something we can see over a longer time span.

So why not see where the high speed camera can be used on a system that normally people associate with very long-term processes? I present to you turbulent flow of some Emriver plastic sand in an open channel flow:

And, here's a bank collapse at 1,000 frames per second. These are tricky, since you don't know exactly where the bank is going to collapse and the high speed camera is fussy enough that you need to have everything locked down while shooting:


  1. Thanks Matt! Our Em2 models really are a labor of love, and we'll always price them so that educators can afford them, that's a big part of our mission at Little River Research. We are now planning a non-profit org to help with that, and also get models to people who could not otherwise afford them.

  2. And RE bank collapse from a thousand-hour veteran of Em2 movies; a tap from a soft blow hammer to the box, um, sorry, "simulated seismic event," sometimes causes banks to fail just when you want them to.