Notation

L

Length, e.g. of a reach, channel or swale (usually in m)

m

run of side slopes in channel cross sections (length, but usually expressed as a ratio in relation to rise. e.g. where side side slopes = 1:3.5, m = 3.5)

q

infiltration rate in (length per time, usually mm/hr) (before or after application of safety factor?)

Q_p

Peak flow in units of volume per time (e.g. m³/s)

R_a

Existing rise of swale gradient (length, usually m)

R_b

Rise of compensation gradient for an enhanced swale (length, usually m)

SCF

Safety correction factor (dimensionless)

y

Depth of water (length, usually m or sometimes mm)

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.

The rate at which stormwater percolates into the subsoil measured in inches per hour.

Vegetated open channel, with check dams; designed to convey, treat and attenuate stormwater runoff.