Enhanced grass swales

This article is about installations designed to capture and convey surface runoff along a vegetated channel, whilst also promoting infiltration.
For underground conveyance which promotes infiltration, see Exfiltration trenches.
For conveyance along planted channels, on both surface and underground, see Bioswales.

=Overview

The fundamental components of an enhanced grassed swale are:

• Graded channel
• Resilient turf grass
• Check dams, to facilitate short term ponding

Additional components may include:

• Amended soil, to increase infiltration to soils below
• Impermeable membrane, to prevent infiltration to soils below
• Turf reinforcement, to prevent scour

The portion of water precipitated onto a catchment area, which then flows as surface discharge from the catchment area past a specified point.

Water from rain, snow melt, or irrigation that flows over the land surface.

The slow movement of water into or through a soil or drainage system.

Penetration of water through the ground surface.

A shallow constructed channel, often grass-lined, which is used as an alternative to curb and channel, or as a pretreatment to other measures. Swales are generally characterized by a broad top width to depth ratio and gentle grades.