Rain Gardens-A Better Way to Manage Storm water

The following chapter is excerpted from the newly released conservation landscaping primer entitled, Eco-scaping Back to the Future...Restoring Chesapeake Landscapes.. Click here to order your copy!
Complementary Garden Arrangements

Rain gardens and xeriscapes often complement one another. If you create them together, you can even think of them as “yin and yang” gardening. Rain gardens are generally designed as shallow, saucer-shaped ponding areas planted with moisture-loving native plants; while xeriscapes (which are covered in the next chapter) can be ground level or mounded areas that tend to be drier and are planted with drought-tolerant native plants. Often, when grading is done to create one of these types of gardens, it presents conditions for creating the other type. For example, when a shallow depression is made to create a rain garden, the excess soil can be used to create a mounded xeriscape, which is a drier type of landscape arrangement. Leaving or creating depressions in the landscape promotes storm water infiltration and reduces storm water runoff.

What is a Rain Garden?

Rain gardens are low-lying saucer-shaped garden areas that have absorbent soils which temporarily collect stormwater runoff, usually from a roof, pavement, or other impervious surface, and allow it to slowly percolate into the soil. This provides flood control, groundwater recharge, and water-cooling benefits, while the plants, soils, and associated microorganisms remove many types of pollutants—such as pesticides, oils, metals, and other contaminants—from storm water runoff. A rain garden is one type of “bioretention” landscaping feature that is a depression into which water will flow.

Properly designed and maintained, rain gardens are attractive landscaping features that function like a natural moist garden, moist meadow, or light forest ecosystem. They can look as naturalistic or as formal as you like.

Benefits of a Rain Garden
Our man-made system of curbs, gutters, and storm drains quickly carries storm water runoff directly to local streams, rivers, and the Chesapeake Bay without any natural filtering process. “We tend to think that large industrial polluters cause most water pollution, but this is not the case. We are the real culprits. CA Studies by the US Environmental Protection Agency have determined that up to 70% of the pollution in our surface waters is carried there by storm water runoff. Some studies show that about 50% ofCAsuch pollution comes from individuals and homeowners, due to yard care, yard waste, and chemical pollution from household activities.”18

Rain gardens serve several important functions in conservation landscaping. Storm water pouring off hot roofs, pavement, and other impervious surfaces is temporarily captured, cooled, and allowed to percolate into the ground. This provides flood control, groundwater recharge, and water-cooling benefits. Stormwater is able to reach a more healthy temperature for fish and other wildlife by the time it slowly makes its way to the Bay. In addition, this living filter system removes many types of pollutants from stormwater runoff. Nutrients such as nitrogen and phosphorus, which would otherwise contribute to algae blooms and other problems, are taken up by the plants in the garden. Sediment that carries pollution and buries plants and animals in the Bay is trapped before it can reach a waterway. Rain gardens also tend to become wildlife oases with colors, fragrances, and the sights and sounds of songbirds and butterflies regularly visiting your garden.

By creating a rain garden and keeping most of the rain that falls on your site contained on site—the way nature intended—you can help improve water quality in local streams, rivers, and ultimately the Chesapeake Bay. Rain gardens save water, reduce pollution, and help wildlife—all at the same time.

Continue... @ Source: Chesapeake Ecology Center