Monday, October 31, 2011

Halloween Stream Table Run

Today's stream table run was an adventure in basin geometry. I've been wanting to find a way to keep the stream from getting hung up on the sides of the table.

I have a bunch of rubber sheeting left over from a roofing project. Yes, I saved several square feet of sheet rubber. Because I'm an experimentalist. And I used it to created coved corners at the base of the table. I built up curved sides with the plastic media and then draped the plastic over it.

The finished sub-base, prior to filling with additional media.

Here's about a 4-hour time lapse. You can see the stream pull away from the side of the table on a few occasions, but I think I may try and make the angle a little shallower.


  1. Very interesting. We haven't tried that. But from my urban stormwater engineering experience I'm guessing that you're getting flow concentration and piping along that outer boundary which will not push the channel away but will, as if by some supernatural force (!) pull it in. We tend to start with a "valley" that's sloped towards the center (cross-ways), which tends to force things away from the wall. You would see this in your lab manual. Which you have read, right? :-)

  2. On second thought, do NOT read the lab manual, it'll just slow up your creative juices, keep trying stuff!

  3. Steve,
    I've read parts of the manual - and yes, sloping the media towards the center helps. But during long runs (2+ hrs), the shear strength of even big piles of media along the edges isn't enough to prevent that "curl over" and piping.

    Actually, I like reading the manual. It keeps me from doing something utterly foolish, but also gives me ideas about what has already been done. Then I do something else.