A swale is a shady spot, or a sunken or marshy place. In US usage in particular, it is a shallow channel with gently sloping sides. Such a swale may be either natural or human-made. Artificial swales are often
infiltration basins, designed to manage water
runoff, filter
pollutants, and increase rainwater
infiltration
Infiltration may refer to:
Science, medicine, and engineering
*Infiltration (hydrology), downward movement of water into soil
*Infiltration (HVAC), a heating, ventilation, and air conditioning term for air leakage into buildings
*Infiltration (me ...
.
Bioswales
Bioswales are channels designed to concentrate and convey stormwater runoff while removing debris and pollution. Bioswales can also be beneficial in recharging groundwater.
Bioswales are typically vegetated, mulched, or xeriscaped. They consi ...
are swales that involve the inclusion of plants or vegetation in their construction, specifically.
On land
This swale concept has also been popularized as a
rainwater harvesting and
soil conservation strategy by
Bill Mollison,
David Holmgren, and other advocates of
permaculture. In this context it is usually a water-harvesting ditch on contour, also called a ''contour
bund''.
Swales as used in permaculture are designed to slow and capture runoff by spreading it horizontally across the landscape (along an
elevation contour line), facilitating runoff infiltration into the soil. This archetypal form of swale is a dug-out, sloped, often grassed or reeded "ditch" or "lull" in the landform. An option is to pile the spoil on to a new bank on the still lower slope. In which case a bund or
berm is formed, mitigating the natural (and often
hardscape-increased) risks to slopes below and any linked watercourse from flash flooding.
In arid and seasonally dry places, vegetation (existing or planted) in the swale benefits heavily from the concentration of runoff. Trees and shrubs along the swale can provide shade and mulch which decrease evaporation.
On beaches
The term "swale" or "beach swale" is also used to describe long, narrow, usually shallow troughs between ridges or
sandbars on a beach, that run parallel to the shoreline.
See also
*
Contour trenching
Contour trenching is an agricultural technique that can be easily applied in arid sub-Sahara areas to allow for water, and soil conservation, and to increase agricultural production.
Between two trenches crops can benefit during the growing se ...
*
Gutter
*
Keyline design
*
Rain garden
*
Stormwater
Stormwater, also spelled storm water, is water that originates from precipitation (storm), including heavy rain and meltwater from hail and snow. Stormwater can soak into the soil ( infiltrate) and become groundwater, be stored on depressed la ...
*
Water-sensitive urban design
Water-sensitive urban design (WSUD) is a land planning and engineering design approach which integrates the urban water cycle, including stormwater, groundwater, and wastewater management and water supply, into urban design to minimise environme ...
References
External links
Fact Sheet: Dry and Wet Vegetated Swalesfrom
Federal Highway Administration
Wetlands of the Great Lakes: The Beach Swale & Dune and Swale Typesfrom
Michigan State University
Michigan State University (Michigan State, MSU) is a public university, public Land-grant university, land-grant research university in East Lansing, Michigan. It was founded in 1855 as the Agricultural College of the State of Michigan, the fi ...
Video showing swales used to rehabilitate desert terrain
{{Wetlands
Environmental engineering
Landforms
Landscape
Sustainable gardening
Sustainable design
Water
Water pollution
es:Zanja