A swale is a shallow, broad, and vegetated channel designed to manage water runoff, reduce erosion, and increase water infiltration. In permaculture and ecological design, swales are used to capture and direct rainwater into the soil, replenishing groundwater and providing moisture to adjacent plants. By slowing down water movement, swales help prevent soil erosion and promote the growth of deep-rooted plants, which further stabilize the soil. Swales also improve soil fertility by trapping organic matter and nutrients carried by runoff, creating a more productive and resilient ecosystem.