Ben, are you asking if logs can be used as water harvesting berms? That's how I use them. Even though I have a lot of rocks, there are some places where it's easier to use logs or piles of brush, so I do. Eventually they will rot away, but before then they will have helped stabilize slopes so plants can grow.
Idle dreamer
You'll find me in my office. I'll probably be drinking. And reading this tiny ad.