Kelly,
You're thinking about a lot of the same things as I am. I'm from western Colorado (hi Adam, it's Linc over on Pitkin Mesa). My land is similarly sloped as yours and has furrows to carry the water from the gated pipe at the top downhill to the tail ditch. I have plenty of early (snowmelt) water (lasts from end of May to as long as end of July), then very little (5 to 20 gpm) water for the rest of the summer (or last year, until only July 23rd, when the reservoir emptied).
I've divided the 3 acres of the field that I farm into four fenced paddocks for rotational grazing of goats, chickens, possibly other livestock in the future. Between each paddock is a fenced 15' wide strip for trees as windbreak, orchard, coppice material for the goats, etc.
Because of the limited water after the snowmelt water is gone, and because I really like the idea of a storage pond like Adam mentioned, along with swales with tree-planted hugelkulture mounds on the downhill side of the swales, I am starting to convert one paddock from standard gated pipe flood irrigation to a series of on-contour swales, each fed off of a ditch that runs downhill along the side of the paddock. I'm doing this mostly by hand, with not a lot of time this spring to work on it, but am hoping to have at least the first 100' or so of the first paddock done in a couple of weeks. I am thinking of creating a series of 70' wide (width down the hill) "terraces" with a feeder swale at the top of each terrace, and a catch swale with hugelkulture mound at the bottom of each terrace, then repeat. The feeder swale would be fed water by tarp dam (flag dam) out of the main ditch. This feeder swale could be called a Spreader Drain (see this link
the basics of permaculture design) that hopefully will allow me to flood irrigate each terrace with the small amount of water that I may have available (first pond I make may be pretty small). The catch swale at the bottom will then catch the excess flood water and let it soak into the hugelkulture mound on the downhill berm of the swale.
I have never seen this done - just hoping it will work. If it does, I may convert more of the paddocks to this system. My main concern is that this system will be more labor intensive than the gated pipe and furrow system, but it may allow me to make better use of the small amount of water I have in mid to late summer.
The next problem will be figuring out how to keep the goats inside movable electric fencing and off of the trees on the hugelkulture mounds.
I am also planning on ripping the soil in each terrace on contour (not on keyline, just right on contour) this fall. I don't have a Yeoman's Plow, so will just use a single shank ripper (Northern Tool has one for $109, but it appears to not have any shear bolts, so risky in our rocky soil). I don't know how well ripping on keyline or contour will work if you also intend to have furrows down-slope. Seems like you'd have to remake the furrows after ripping. Might be better to do away with the furrows if you try the swale system so that you can sheet flow out of the feeder swale. Again, I don't know how well an on-contour feeder swale (or Spreader Drain, as described above) will work until I try it.
By the way, I planted a dryland pasture grass mix (cool season grasses that go dormant in summer), along with a mix of drought tolerant Ladak Alfalfa and Yellow Sweet Clover two years ago when we had a wet spring. It came up great and made it through the drought with no irrigation from late last July until this spring. That Ladak has some great water-seeking taproots.
We have another permies list reader in this valley who is doing somethings similar (hi Lisa, if you're reading this). She and her husband are in the process of creating a series of on-contour swales about 20' apart in their pasture. Each swale is fed by a main ditch that runs downhill along the side of the pasture (as I'm working on doing). On each side of each swale, they are planting trees. They are not planning on flood irrigating the pasture between each swale, but instead are hoping that the water in each swale will seep through the soil to sub-irrigate the pasture.
Anyone else out there with flood irrigation that has tried to go to contour irrigation, or swales instead of the downhill furrow flood irrigation?
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