Hi Owen, I have a question using whole-farm Keyline Design and integrating irrigation water from off-property storage (we have ditch water rights through our irrigation department).
Like most western mountain valleys (we live in the Mission Valley of Montana) snow melt is stored in mountain reservoir and the distributed throughout the irrigation season through a series of ditches controlled by our irrigation department. Most folks pump it through expensive pipe and sprinklers using subsidized cheap electricity. Cost alone is enough to prevent me from doing that, but i feel there is a better way...enter Keyline.
I like the benefits of passive rain water catchment and distribution through Keyline, but also want to establish ditches for "flood-flow" irrigation during the dry months using these off-property water stores. My question is- after plowing on Keyline, how should i cut my irrigation ditches related to contour? Our water enters from a single point on the high spot of our property, so from there if i route my ditches along the Keyline, sloping down from the valleys towards the ridges, i couldn't continuously deliver my water around multiple ridges. It would stop at the first ridge. So should i continuously slope these delivery ditches on an approximate 1:400 downward slope to deliver the water across my entire property? I figure about 200' between these ditches, with trees planted on the downhill berm, creating basically an alley crop system that is plowed on Keyline between each ditch. I would then use plastic dams to flood-flow each section between ditches. Am I on track? Thoughts for improvement?