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?
Thanks for your question... seems like you've already a good general grasp of the keyline concepts, which is great... and yes, you sound to be on the right track with how you describe your plan (difficult to say exactly, or to suggest meaningful improvements without maps and details, but the concept sounds right, along with the general slope ratio you describe for irrigation drains).
Your property sounds somewhat mountainous (as opposed to flat country)... and 'technically' my understanding of 'flood flow' systems were developed more specifically for areas of fairly flat land, so might not be what you intend (we will cover these systems in the upcoming Colorado course). Nonetheless, keyline irrigation in general sounds like it could be a useful way to irrigate your land with less expense than many pipe and sprinkler set-ups... though some low-pressure and low energy systems using sprinklers, such as K-line, might also be an option? Trees can be planted out both above and below irrigation drains, or one or the other alone...
Sounds like you are heeding the Scale of Permanence as you are thinking through the design, which is a proven and effective approach... Keep up the good work, Michah!
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