Rainwater Harvesting and Stormwater Reuse for Arid Environments - Design with the Desert: Conservation and Sustainable Development - page 374

TABLE 21.2
Low-Impact Objectives and Techniques

Low-Impact
Development Objectives

Minimize disturbance • • • • • • • •

Flatten grades • • • • •

Reduce height of slopes • • •

Increase flow path (divert
and redirect)

• • • • • •

Increase roughness • • • • • • • •

Source: Kinkade-Levario, H., Forgotten Rain, Rediscovering Rainwater Harvesting ,
Granite Canyon Publications, Forsyth, MO, 2004.

to allow longer standing/infiltration periods. Swales can be located next to sidewalks,
paths, and driveways and typically direct stormwater toward vegetation and away from
buildings. They can be designed to follow or parallel the contours as well as be designed
to be at a slight angle from the contour. Swales designed at a slight angle from the contour
are more appropriate for larger areas such as parks, but the smaller swales can be designed
as small pocket swales similar.

21.5.2.3 French Drains

French drains and rain gardens are meant to rapidly infiltrate stormwater and to remove
standing water from surface view. French drains are typically lined transport channels
leading to subsurface storage areas or overflow infiltration areas, or providing a faster
transport to plantings such as a rain garden.

21.5.2.4 Rain Gardens

Rain gardens use the concept of bioretention, a water quality practice where plants and
soils remove pollutants from stormwater naturally. Proposed retention/detention basins
can be placed at the lowest elevation on a site to assist with infiltrating excess stormwater.
Large basins are perfect locations for rain gardens, which are created with layers of soil,
sand, and organic mulch. These layers naturally filter the stormwater as it flows into a
basin/rain garden and as the stormwater infiltrates through the layers. Excess water is
stored in the soil voids or infiltrates through the soil. Rain gardens can also be designed