A swale is a low tract of land, especially one that is moist or marshy.[1] The term can refer to a natural landscape feature or a human-created one. Artificial swales are often designed to manage water runoff, filter pollutants, and increase rainwater infiltration.[2]
The swale concept has also been popularized as a rainwater harvesting and soil conservation strategy by Bill Mollison, Geoff Lawton and other advocates of permaculture. In this context it usually refers to a water harvesting ditch on contour. Another term used is contour bund[3][4]