I think that was a joke, but I in case it isn't: swaling (this kind of swaling) concentrates rainfall. It's a neat feature of how water flows through soil. My question is, over time entropy will be working to flatten everything back out and fill the holes. As it rains, soil will erode back into the holes - maybe quicker that it takes for plant roots to establish and hold the bowl-shape. Large-scale, earth-mover-size projects make big swales that are more resistant to erosion. For such small swales to hold their shapes, I'd expect they'll have to establish plants in the bowl first, which might be hard if it's arid soil - they'll have to port in water to get the surface plants established.

It all seems harder than just digging craters and planting a tree in the middle. But I'm pretty ignorant about all this - happy to hear from someone with experience in this area!