I've never been to the Arizona desert, but it's not the first place I'd think of for growing quality squash and corn—especially without supplemental irrigation. But Homestead Economics has a neat video of their rainwater garden system, which collects stormwater runoff from a long dirt driveway, diverts it to carefully designed grow beds surrounded by a berm, and then collects any excess water in a retention pond for future irrigation. Apparently, the end result is abundant squash and corn without any need for additional irrigation.
Here's a view of the garden when the rain actually starts pouring, with the water streaming off the driveway and here flowing around the corn bed.
And here's the very simple board system that's been installed to reduce sediment from flowing into the garden:
What's most impressive about this video is just how simple an effective permaculture design can be. Using the old maxim that "the problem is the solution," this design captures stormwater runoff—usually a cause of soil erosion—and turns it into an abundant resource for times of scarcity.
Check out the full video for how this very cool garden was put together.