Difference between revisions of "Notation"

From LID SWM Planning and Design Guide
Jump to navigation Jump to search
Line 6: Line 6:


;D :Duration of the design storm event (in units of time, usually hrs)
;D :Duration of the design storm event (in units of time, usually hrs)
;d<sub>p</sub> :Surface ponding depth of an infiltration practice (unit of length, usually mm or cm)
;d<sub>m</sub> :Filter media depth of a bioretention, stormwater planter or soil cell practice (unit of length, usually mm or cm)


;d<sub>T</sub> :Total depth of an infiltration practice (unit of length, usually cm or m)
;d<sub>T</sub> :Total depth of an infiltration practice (unit of length, usually cm or m)

Revision as of 17:49, 22 April 2020

Ac
Area of the catchment, whole contributing drainage area (usually in m2).
Ai
Area of impervious cover within the catchment (usually in m2).
Ap
Area of the practice e.g. footprint area of a bioretention cell (usually in m2)
D
Duration of the design storm event (in units of time, usually hrs)
dp
Surface ponding depth of an infiltration practice (unit of length, usually mm or cm)
dm
Filter media depth of a bioretention, stormwater planter or soil cell practice (unit of length, usually mm or cm)
dT
Total depth of an infiltration practice (unit of length, usually cm or m)
f
Infiltration rate, measured (usually mm/hr)
f'
Design infiltration rate (length per time, usually mm/hr) after application of safety correction factor (SCF)
h
height (units of length)
i
Intensity of the design storm event (in units of depth/time, usually mm/hr)
i
Thornthwaite monthly heat index (-)
I
Thornthwaite annual heat index (-)
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. side slopes = 1:3, so m = 3)
n
Porosity, applies to aggregate and other void-forming materials, filter media and native soils (unit is vol/vol, so dimensionless)
n
Manning's coefficient (unitless) Note: the symbol n is also used for porosity so it is important to be sure which term is implied.
N
Number of days in the month
Qp
Peak flow in units of volume per time (e.g. m3/s)
R
Ratio of catchment (Ac) to the practice footprint area (Ap). syn. I/P ratio. For green roofs (and often permeable paving systems) this will be 1:1. In bioretention it may be 15 or 20 to 1.
Ra
Existing rise of swale gradient (length, usually m)
Rb
Rise of compensation gradient for an enhanced swale (length, usually m)
RVCT
Runoff volume control target (as outlined by MECP, units are mm)
S0
Longitudinal slope (m/m, i.e. dimensionless)
ST
Storage (m3)
Sx
Cross slope (m/m, i.e. dimensionless)
SCF
Safety correction factor (dimensionless)
t
time (usually in hrs)
T
Temperature (°C)
V
Volume (usually in m3)
x
Perimeter of infiltration practice or swale x-section (m)
y
Depth of water (L, usually m or sometimes mm)