Climate change is bringing significant challenges in the form of increased rainfall and flood risk. Rain gardens offer an effective and attractive way to reduce flood risk and treat surface water runoff whilst also helping provide additional biodiversity and a greater sense of place to city centre streetscapes. Designed to capture rainfall both from the streets and footways, rain gardens offer an area for runoff to initially pond on it’s surface before filtering through the vegetation and underlying soil mix. Through the filtration process, rain gardens also provide an effective water treatment process, removing contaminants such as oils and metals deposited from the roads and pathways. This allows for a cleaner outflow which helps protect the environment.
In Glasgow, we tested a series of trial raingardens and were able to show that the rain gardens reduced the levels of contaminants in the stormwater and the stormwater was suitable for release into the River Clyde. There were small differences in pollution removal depending on what soil and aggregates were used in the raingardens, but all were able to reduce pollution levels in the water. We are also exploring how good bacteria in the raingarden soil help to remove the pollutants. Here at Anderston-X we are researching how these raingardens can remove pollutants from water running off from the busy M8 motorway above.