Rain garden
A Rain garden is a planned, eco-friendly, natural space strategically placed within otherwise environmentally unfriendly urban spaces. Rain gardens function like native forests to help slow, soak up, and filter polluted urban runoff from downspouts, driveways, parking lots and other hard surfaces. Typically, a rain garden is a designed shallow recessed surface containing flowers, small trees, shrubs and grasses designed to tolerate wet winters and dry summers. Also known as bioretention ponds, rain gardens are typically designed by landscape architects or designers to reduce the rate of flow of runoff from heavy rains or snow melt and filter the pollutant load originating from road treatment chemicals and other sources.
Rain gardens are beneficial to local environments in many different ways. Stormwater flowing off impervious surfaces in urban areas is often warmer than natural groundwater and may even contribute to overheating in some aquatic ecosystems as well as the reduction of dissolved oxygen (DO). Stormwater runoff flowing off hard or compacted surfaces during rain is also a source of a wide variety of pollutants pollutants including many different volatile organic compounds, pesticides, herbicides, hydrocarbons and trace metals
Especially important in areas prone to flash flooding in creeks and rivers, rain gardens also provide first-stage and localized flood control near the source. They can also improve water quality by filtering runoff. They also encourage sustainability for wildlife and biodiversity and encourage diverse planting opportunities. Rain gardens also have the potential to create aesthetic landscaping sites, and potentially tie buildings and their surrounding environments together in environmentally advantageous ways. Altogether, they provide significant solutions to important environmental problems that affect many aspects of life.
Open downhill lots, small green spaces in alleys and parking lots, barriers between rows for parked cars in parking lots, traffic islands, low spots outside large buildings (especially those on the low sides), existing creek beds and drainage ditches, and an almost infinite variety of additional urban spaces are all potential rain garden sites.