definition

A swale is a low tract of land, especially one that is moist or marshy. The term can refer to a natural landscape feature or a human-created one. Artificial swales are often designed to collect water runoff, and increase rainwater infiltration, therefore reduce runoff. They can be covered by grass or other vegetation and have shallow side slopes and a flat bottom which means that for most of the time the water flows in a thin layer through the grass or other vegetation. Three main types of swales can be defined according to Kellagher (2005). Larger swales with a focus on rainfall runoff attenuation are mostly situated besides roads or parking places with a depth of about 0.4m, a width of about 5m at ground level and 1m at the bottom level. Smaller swales, so called "mini-swales", could be designed with a width of about 1m and a depth of 0.1m which are used to receive rainwater runoff, store it for infiltration and drain the runoff into the drainage once it is full.
(Wikipedia, Swale, accessed on Sept. 2016)

Co-benefits and impacts

Vegetation in swales allows for filtering of pollutants, and infiltration of runoff into groundwater. Densely vegetated swales can be designed to add visual interest to a site or to screen unsightly views. Broad swales on flat slopes with dense vegetation are the most effective at reducing the volume of runoff and pollutant removal
(Water Harvesting Solutions, Vegetated Swales, accessed on Sept. 2016).

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Last modified: Sept. 19, 2016, 12:19 p.m.