Swales are vegetated, linear and low-sloped pits (larger than rain gardens) often established in urban areas near and between roads. They absorb, store, and convey surface water runoff (mainly draining from roadways) and remove pollutants and sediments when the water trickles through the vegetation and soil layer. Additionally, swales can serve as traffic harassment and can be implemented in combination with other NBS
Benefits
(+) Usually vegetated with grasses or other low maintenance plants
(+) Correctly sizing, will provide adequate drainage and removal of particulate pollutants
(+) the required elevation change is minimal
Limitations
(-) Limitation for planting trees: habitat provision is limited to ground level
(-) Risk of blockages in connecting pipe work
(-) Risk of pollution to groundwater depending on site.
(-) Prone to channelization and erosion in the absence of appropriate vegetative cover maintenance.
Assessment
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