I have an acreage design I am working on that has a small food forest (6 fruittrees with guilds). It will be positioned on a hill at a gentle gully that i would like to dam off to slow/store water in a very small scale. if the gully dam w/overflow is just for the food forest do I need to incorporate Swales into this as well or could I just have the food forest around the tiny reservoir. I am not used to food forests with ponds and want to keep the price to a minimum. I understand dams are compacted so that is another concern for planting around it. I see Geoff Lawton build a gazillion Swales and ponds on properties but my scale/budget is pretty small so I want the smallest scale design so my energy input for the food forest is inline with the food forest outputs. I also would like to take advantage of the only water catchment on the property. Suggestions as to where to locate food forests on an acreage would be helpful as well. I am choosing water/planted windbreak over clearing trees and inserting inside a mature windbreak.
I would think the two most important factors are your local rainfall and topography. If you make up a topographic map for your site and study it, you will see the natural locations for putting a catchment. Maybe just a half-circle a little downhill from your trees and pack some clay and organic matter as absorbent material will be enough. It really depends on your rainfall. If you know the optimal rainfall for your trees, and yours is less than that, then you have an idea of how big the catchment will have to be to collect that amount of water. For instance, if you get 12" and your trees do best with 48", then you know that your catchment should be about 4 times the area of the mature drip line circle of the tree.
If I get you right and you are going to do this at the single tree level, it sounds like something you could do with just a shovel in a few hours; build up a berm downhill of your trees to slow and collect the natural rainfall. If you are more industrious, you could make an arced hugelkultur mound at a radius from the tree and plant it with other plants you want in your food forest.
If you put a berm across the gully and end up making a (seasonal) pond, then you will have to look into plants that can tolerate being flooded. And I will be glad to help you with that, because I'm giving away bald cypress seeds.
Thanks for the suggestions John. Apparently all the trees my partner is planning do not like too much water. What we decided to do is form a small catchment with overflows and feed it into 3 concurrent swales on contour. Just creating enough swale for the trees and to divert water around a structure.