Reconfigurable swale

Discussion in 'Designing, building, making and powering your life' started by Mike_E_from_NZ, Feb 7, 2009.

  1. Mike_E_from_NZ

    Mike_E_from_NZ Junior Member

    Oct 2, 2005
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    We are getting the heat wave here in NZ too. Apparently some of our days are hotter than the Aussie days. Not many, but some. A nice downpour would be great, since I have a couple of swales that would stop the runoff in its tracks and let it soak in (probably in 3 hours, rather than 3 days at the moment).

    I am about to plant (well, not *now*, but when the autumn rains start) a subtropical food forest. The terrain just screams "swales", but the soil type screams "slump". No slumps there at the moment, nor in the heaviest rains, but I do have slumps on my property. This area drains quite well, and is the driest on the property in our wettest winters.

    However, you can see that "well drained" becomes "not so well drained" when the slope is interrupted with swales.

    Enter the "reconfigurable swale". Picture this:

    Swale dug on contour with spill way beyond the next lower swale so that swales don't drain into swales. At the spillway a pipe is buried in the swale wall at the swale depth. One end is in the swale, and an elbow at the other end of the pipe which is outside the swale.

    In the winter the elbow is turned down so that the water cannot sit in the swale: swale is basically empty, and thus forms a drain.

    In spring the elbow is turned up so that the water cannot run through the pipe: swale is able to fill to the spillway depth.

    Questions for discussion:
    1. Do I risk slumping anyway. Geoff Lawton warned me against putting more water into areas at risk of slump. But I'm not really am I? It is not at risk of slump during the spring and summer. And I am not infiltrating water during the winter.
    2. Do I bother offsetting the spillway so that it doesn't drain to the next swale? As long as the winter drainpipe doesn't.

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