DEFINITION
A channel or runnel used for water conveyance from one place to another. This could be from a downspout or scupper to a stormwater planter, a channel along a pedestrian walkway that drains into a lake or river, etc. It is usually decorative in nature due to its high visibility through a public space but does not include planting, filtering or infiltration.

AKA
Runnel, swale

PERFORMANCE CRITERIA
Measurements can include: hydraulic capacity, physical dimensions (length, width, depth), type of lining (vegetated, flexible or rigid).
Criteria for design: Entire textbooks have been written describing the process of designing stormwater conveyance channels. Suffice it to say some the more important factors that must be considered are: amount of water they are to carry, constructed cross-section, planned length, difference in the elevation at the entrance and exit points and proposed lining.

ILLUSTRATION
Although the types of stormwater channels are infinitely variable, the following illustration is representative of the most simple type.

(Source: U.S. EPA)






Two examples of stormwater conveyance channels in pedestrian areas in southern Germany.
Both empty into Lake Constance.

CASE STUDIES
Stephen Epler Hall, Portland State University, Portland
Park Guell, Barcelona
Arkadien Asperg Housing Development, Stuttgart, Germany
Parque de cabecera, Valencia, Spain
Stormwater Training, Austin, Texas

ADDITIONAL RESOURCES
Open Channel Design @ http://www.knoxcounty.org/stormwater/pdfs/vol2/7-4%20Open%20Channel%20Design.pdf