John Elliott wrote:More power to you. I grew up in that area (the eastern California desert), and decided that it's too hard to make a living there, so I'm now in a much more rainy climate. But if you want to make a living there, you left out the most important piece of information -- what are the swales for? Do you want to grow oranges? Mulberries? Pistachios? Pomegranates? Native desert species like palo verde? To make the most of your rains, each plant is going to have to be fit to each swale, and I know that implies many swales and not "one deeper swale". But your assumption that the sun will come out and dry things up quickly is in error; on the rare days that it does rain, it tends to be a steady rain for many hours (winter) or a downpour of >1" (summer). In fact, that's what it takes to germinate creosote bush seeds -- a summer downpour of >1".
Also, you will be making less work for yourself, if you look at what sort of natural swales and water collection spots are there to begin with and build on them. This requires a discerning eye to be able to spot the feral palo verde or ironwood or prickly pear and the inquisitiveness to ask "now where is this plant getting its water in the infrequent rains?"
I have a project report that San Diego State did on a revegetation project at Ft. Irwin that involved the building of many small swales. If you will send me a PM, I would be happy to provide you a copy of the report. It may give you some ideas on how to build your swales and what plants you can get to grow in them.