I didn’t forget to follow up on this! Unfortunately the coordinator that was responsible for planning the plant layout is gone visiting home for the next month, and the other coordinator didn’t know as much about it (beyond that the coordinator that sets this up knows a lot about it!). Another volunteer remembered what I was talking about and was able to tell me that they were utilizing both a combination of rocks to slow down the water flow (giving it more time to absorb into the soil) that one of the plants being used is called mule fat (Baccharis salicifolia), and that it’s generally beneficial to plant within what’s known as a “plant guild” of plants that all tend to grow together and serve different functions in the ecosystem.

Sorry I couldn’t get you more info! If you want to wait longer I can follow up with more details once the coordinator that actually planned the layout and everything gets back, but I wanted to go ahead and let you know what I did find out in case that gives you a good jumping off point.

The way it was explained to me was that as the plants we’re putting on an incline grow and intertwine their roots, just normal water uptake from the roots closest to the water source (a spillway for us) will result in some water very slowly making its way uphill underground into the surrounding soil, via the roots. And then the next plants closest to the plant closest to the water will start taking up that water, and repeat the process. I have no idea of this is a local adaptation for Southwest US plants or something that all plants everywhere do, I just show up to haul shit around and listen to all the knowledge the project leaders have! If you feel like waiting a week and a half I can ask for more specific resources about it.