I’ve leaped across another good drainage sample to show you. The rocks hold the soil in place, but allow the water to seep into the ground if it can, which Ol’ Wally here thinks is important. Why cart the water off to someplace there is more water when we need it right here, on our plants, nurturing our trees.
The humans here extended this permeable channeling back a ways so it directs the water away from their structures.
You can see places the water is collecting and staying damp–like where the moss is growing. This is a good thing! More little niches the little plants can get a root-hold in.
Good job, human folks!