I lived and gardened in GA for 20+ years and I wouldn't call it a dry climate. Nevertheless, only about one year in four would there be
enough regular summer rain to grow a garden without supplemental irrigation, so I can understand the benefits of swaling.
If your soil is a clay, you must beware of planting certain things in any situation where water has a chance of standing for any length of time, even in locations where it may later dry out completely. Fruit
trees, especially, are likely to drown in such spots, especially if the waterlogging occurs during the growing season (which isn't common, but it does happen often enough in that climate to be a concern). Thus the frequent recommendation to plant your permanent, important plants on the ridges of the swale, especially the downslope one, where the lower
roots can access the plume of moisture working its way from the swale, while the base of the plants remains well out of the danger of excess water in the wet times. Down in the swale is the place for soil builders, coppice plants, pasture grasses, perhaps low-investment annuals in the first years till shading becomes an issue.
If however your soil is a free-draining sand.....and there are plenty of places in the state that are thus, where it can rain 4 or 5 inches in a summer storm and there will be no puddles an hour later, and you can light the pine
straw on fire two hours later.....in those spots the bottom of the swale might be a very good place to grow in, since you want all the extra moisture, and the organic matter that will end up there by default......