Swales are linear depression of channels that provide for stormwater collection and conveyance. Swales may simply be grass-lined or more densely vegetated and/or landscaped. While swales provide for stormwater conveyance, they also lend to the screening or removal of gross pollutants, such as litter and coarse sediment, from stormwater runoff.
In urban areas, swales may be used as an alternative to the conventional street nature-strip or in central median strips of roads, through to runoff collection points in carpark areas.
Comprehensive guidelines for the design of swales can be found in Chapter 8 "Swales and buffer strips" in the WSUD Engineering Procedures available for purchase from CSIRO publishing.