Swales v Keyline

Discussion in 'Planting, growing, nurturing Plants' started by crowsandcats, Jan 24, 2018.

  1. crowsandcats

    crowsandcats New Member

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    when should contour swales be used and when should keyline be used?

    I've only heard some brief suggestions, but maybe someone has this figured out. Any scientific approached with side by side systems?
     
  2. songbird

    songbird Senior Member

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    i'm getting rusty now, but the differences are that keyline is set up
    to actively move water away from the places it wants to gather
    so you are designing to use gravity to disperse the water across
    as large an area as possible.

    swales by contrast are usually not used to move water that often
    but to hold it in place.

    both have their uses. i'm sure you could combine them if needed.
     
    Michelle71 likes this.
  3. Bryant RedHawk

    Bryant RedHawk Junior Member

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    Both methods use swales, the original keyline system by yeoman's "water for every farm" refered to first finding the key point (that spot where water begins to cause erosion) and working your swales along the contour line from that point, usually with a pond formed at the keypoint.
    This is the actual "key line system" devised by Yeoman for Australia.
    Mark Shepard, who lives in the USA, discovered that Yeoman's system had major drawbacks for places with more than Tertiary system water sheds.
    This led him to develop his own system which he calls the Main Line System. The biggest difference between the two is the Main line system moves water where the keyline system holds the water stationary. The main line system works better when the slope is between 3 degrees and 15 degrees since the swales for this system are cut at a 1 degree down hill line instead of right on the contour line, this allows the water to move slowly and a series of drive through (shallow) ponds are installed. The system will fill and move water but when a huge rain occurs the swales fill and then the water will sheet down the hill, preventing erosion from occurring. This system will handle the torrents of major storms with little or no runoff the land thus keeping all the water possible and letting it soak in. Several years ago such a rain event resulted in flooding in the area where Mark lives and his farm did not suffer any flooding or massive runoff while his neighbors did suffer from the flooding.
     

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