Tuesday, August 3, 2010

Geomorphically incorrect Art #4.

Kids, not only is the art incorrect, but the advice is, too.

From an old issue of Boy's Life.  Maybe those kids at top reduced the slope of  eroding bank by hand, but I doubt it. 

Willow cuttings only work if you first fix the underlying cause, which in this case is likely over grazing.  Which, unlike more natural meander migration, would leave this outside bend bank with a moderate slope (and with a bunch of hoof prints and dung piles, not pictured, thus the incorrectness).  A well built and maintained barbed wire fence would be the prerequisite here, but I don't see one.

And what bad advice we have next.  Armoring a stream's banks with its bed material.  The stream put those rocks there in the last big flood.  It'll move them again, especially if, like Tony Hawk, they're poised at the top of a ramp, having been given some extra potential energy by well-meaning 1960's Boy Scouts.

Believe it or not, this method is widespread in America's gravel bed streams, at least where it's quasi legal or the law isn't enforced.  The result is always the same, and in fact our last consulting work involved a survey of the aftermath of a project like this.  Only that one was done with lots of Diesel fuel, not barefoot Boy Scouts.

To discourage this sort of thing we modeled the typical stream response in this video.

Disclaimer:  I was a Boy Scout in the 1960's.

3 comments:

Naturalist Charlie said...

I love this video, especially the part where the tiny, cute, but misinformed bulldozer falls into the creek.

Also what was the logic behind riprap helping trout? That is a ridiculous claim even if you ignore all the other odd things in that little blurb.

Steve Gough said...

Charlie, you'd be pretty shocked to know the millions of tons of riprap that've been installed in the name of trout. I am.

Sally said...

I love this series-- great idea, and I'll be back looking for more. "Getting" geomorphology back in college really opened up a world/lifetime of Earth understanding for me... Thanks for the vid clip too.

And riprap? DGMS...