Jim,
That is great advice. I need to do that concept for the proposed garden area.
I built 4 terraces in the front yard(s) exactly like you describe, except they are taller. I used boulders like a retaining wall and a trench to funnel the overflow to where it needed to go. You may have seen them in my Log Home thread? For Brandi's pond, I was trying to convey the idea of channeling that water on her land, the run off she saw, to her pond. On my land, I trenched along the bottom of some areas to collect the run off and route it all to a large culvert. In my case, I didn't want it to flow over the road (which it was doing). My road has gutters cut along it's side, but some areas it spilled over and the road remained wet because it was soaked. By cutting a ditch up away from the road, most of the water collected in that and was routed directly to the culverts into the natural arroyos.
With that in mind, I was thinking trenching is a good way to collect water from much farther away places ... channeling it to get to the terraces and providing additional sources of water for the pond? The trenches get it to the terraces which will slow it down and filter it. When I build my pond, I'll use the dikes and terracing concept for water entering the pond. With growth on the terraces, it should filter out nicely before entering the pond. I believe that's what Brandi wants to do with her run off?