bioswale

A bioswale is a landscape feature designed to manage stormwater runoff by promoting infiltration, filtration, and evapotranspiration through a vegetation-lined swale. They are shallow, vegetated channels that guide runoff along a defined path while treating it through soil and plant processes.

Typically they consist of an inlet and outlet, a sloped bed, a vegetated buffer strip, and a subsoil layer with high permeability. Inlets may include pretreatment to capture large debris. The bottom is gently graded and may incorporate a shallow gravel or sand layer to aid infiltration.

Benefits include reduction of runoff volume and peak flow, removal of sediments, nutrients and metals, and improved groundwater recharge and habitat value. When properly designed, bioswales can be integrated into streetscapes, parking lots, and campuses while contributing to urban greenery.

Limitations include dependence on adequate soil permeability and groundwater conditions; they are less effective in clay or frequently saturated soils. They require pretreatment to prevent clogging, regular maintenance, and sometimes design adjustments to avoid sediment buildup or mosquito habitat.

Design and maintenance considerations emphasize native, drought-tolerant vegetation, avoidance of invasive species, and regular inspection after storms. Tasks include trash and sediment removal, vegetation management, repair of eroded edges, and ensuring unobstructed flow paths and outlets.