Tuesday, August 3, 2010
Geomorphically incorrect Art #4.
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.