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Encourage water flow by putting swales slightly off contour?

 
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Hello,
My question concerns getting the water to move across the landscape. How much deviation from the contour is typical to encourage water flow? Is a slight taper off at the end of a swale appropriate? Or, would it be better to have the entire swale gradually increasing in deviation from contour from end to end? Basically, I want the water to seep back into the landscape but also feed a couple of ponds. Obviously, I don't want to create small raging rivers when it rains, but some movement would be good to keep the ponds full. Any thoughts are appreciated, thanks!
 
Posts: 11
Location: Sonoma Co, CA
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Hi Ryan,

How big of a swale are you planning. All sites are different.. I believe the general recommendation is to take it about 45 degrees off contour or so. If you only have a taper at the end, only the water at the end will flow down the taper... If the rest of your swale is perfectly on contour. Also on contour is supposed to be more prone to slides. Know what i mean?

Are there already any areas where rain had been causing erosion on the site you mention? Pictures?

Terraces may be more appropriate for your site.
 
steward
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Location: Zones 2-4 Wyoming and 4-5 Colorado
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Howdy Ryan, welcome to permies. I guess it depends on how much rain you get per year and how porous your soil is. It seems to me that if you build a swale that fills up during a rain that the water will fill to the same height all along the swale. If your swale is 50 ft or 500 the water will run off where ever you have a low spot, or spillway, in the burm of the swale. It will run to the end of the swale without any deviation. So you put a pond in any "Keyline" point of your land and attach the swale along that contour. Which will fill the pond . Have you seen Darin Doharty's youtubes on this subject?

http://www.youtube.com/watch?v=lsWKyv9Hbak
 
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this thread has some examples that are pulled from Yoeman's Keyline books.
I think this might be an example of what you want to achieve -- no torrents of water.
https://permies.com/t/22543/earthworks/basics-keylines
 
Ryan Boyd
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Thanks for the replies! We have a couple of swales cut, I will add some pictures. As far as marking a keypoint, I understand that this is the point where the landscape changes from convex to concave but how do I mark exactly where this is? Also, on our A-frame we mounted a level on the crossbeam. In my opinion, this is FAR more efficient than waiting for the weight at the end of a string to stop swinging every time you move--yet, its seems kind of funny that all the instructions on A-frame building I have come across do not mention the highly advantageous use of a level.
 
Ryan Boyd
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Swale and A-frame pics
1.jpg
[Thumbnail for 1.jpg]
One of the swales...
2012-09-29-11.05.00.jpg
[Thumbnail for 2012-09-29-11.05.00.jpg]
this is before we mounted the level on the crossbeam
2012-09-29-12.56.52.jpg
[Thumbnail for 2012-09-29-12.56.52.jpg]
larger view swale
 
Posts: 73
Location: Nova Scotia
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Nice work there. Last fall I placed a swale off contour at a 1% grade over 500m, it has worked good for me. My swale wraps around a hillside that focuses the water flow to a future irragation pond site. The water flow is running nice during rains exposing the rocks and gravel in its base. I have added round hemlock logs as small dams in a few areas to slow water flow and to increase areas of water retention for the fruit trees that I have started along the swale. They looks like a fish ladder as they are at 30-40ft intervales, and allow for 6-8 " of water to sit behind them.
 
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Location: Denmark
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I've also been wondering about the idea of making swales on a slight incline so as to direct the water flow from the 'top' of our garden towards the corner where I've installed some raised beds. It's a suburban garden, and my garden beds share the space with a young child and a couple of dogs, so I'm not really at liberty to dig swales anywhere I want. The dogs would probably dig in the swales, and my daughter probably would too, or else trip and fall in!

However, I read in Gaia's Garden about straw-filled swales, and I figure dogs and child alike would probably leave those alone. I also wonder whether this would slow down the water flow? I don't know exactly what the angle of the slope is - it seems rather slight to me - but in case it is steep enough that an open swale would erode over time, I'm thinking a swale with straw, leaf litter, etc. might prevent such erosion. Does my intuition seem accurate?

Thanks for any advice!
Ståle
 
Miles Flansburg
steward
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Location: Zones 2-4 Wyoming and 4-5 Colorado
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I just watched Geoff Lawtons new video on cold weather permaculture and they did talk about the swales that were carrying water being slightly off contour. So I just learned something.
 
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