More Efficient Rain Gardens

Rain gardens have become popular landscape features in recent decades. The gardens are small depressed areas used to catch stormwater run-off from roofs, driveways and other impervious surfaces. Stormwater run-off is a major source of the pollution found in our rivers, streams and lakes. Studies have confirmed the ability of rain gardens to trap contaminants and in some cases convert them to less harmful compounds. A recent study shows how a small design change can help the gardens' ability to reduce nitrates.

Researchers at the University of Connecticut found that designing rain gardens to hold a pool of water at the base produced an 18% decrease in total soil nitrogen levels. The simple alteration reduced the oxygen level in the soil, creating anaerobic conditions favoured by bacteria that convert soil nitrates to nitrogen gas, which returns to the atmosphere.

The research shows the potential for designing rain gardens that target other specific pollutants or that are adapted to regional conditions.

Links:

• Rain gardens blossom as a storm-water management tool from Environmental Science and Technology Online



• Rain Gardens of Western Michigan an environmental education program focused on stormwater education



• Rain Gardens: Improve Stormwater Management in Your Yard from Canada Mortgage and Housing Corporation

Posted by Eric La Fountaine at 1:04 PM on January 16, 2006