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Help! swales vs. keyline - was Yeoman right?

 
scott romack
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Hello,

I am about to put in my first contour swale and was initially going to put in the others on contour but, am seeing that Yeoman suggests to just put in all other swales parallell to the initial 'contour'.

This puts the other swales slightly off contour and this is supposed to pull water out of the lows and into the higher places.
This sound like black magic to me but, does this really work?
What should I read to get a better understanding of this concept?
 
Ben Stallings
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scott romack wrote:this is supposed to pull water out of the lows and into the higher places.
This sound like black magic to me


If it were pulling the water upward, that would be magic. The water is still flowing downhill, but instead of following the shortest path into and along the valley, it's following a longer path along the swale toward the ridge, and soaking into the ground somewhere along the way. Although the ridge as a whole is higher than the valley as a whole, the spot where the water winds up soaking in is lower than the spot where it started.
 
Alder Burns
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All the swales could be level on contour and it would still have this effect in a runoff event, but if most were slightly off contour pointing towards the ridge-points, you would lead the water overflow preferentially there, where it would do the most good....
 
Kelly Smith
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scott romack wrote:
I am about to put in my first contour swale and was initially going to put in the others on contour but, am seeing that Yeoman suggests to just put in all other swales parallell to the initial 'contour'.


The key feature that yeoman was referencing is the keypoint in the landscape. once youve found the keypoint, you start the contour at that level.
from THAT keypoint contour line you plow parallel. this is supposed to help rehydrate the ridges, as it draws water out to the ridge away from the valley in the groves you plowed.
here is the best picture i can find of what is meant:


scott romack wrote:
What should I read to get a better understanding of this concept?

http://www.soilandhealth.org/01aglibrary/01aglibwelcome.html
at the very bottom are 3 books written by Yeoman about Keyline.

hope this helps.
 
scott romack
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Yeah,

Thanks - excellent graphic. I was starting to get it anyway once I figured out how to make contours in sketchup.
Starting from the keypoint makes sure you are using the 'steeper' contour.
I just wanted to understand the concept in case I wanted to make adjustments.

It turnes out that my contours were already used in the past and are pretty uniform already!
Not all the ancient knowledge is lost.
 
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