910

edits
# Changes

## Notation

,no edit summary

;~~L~~A<sub>c</sub> :~~Length, e.g. ~~Area of ~~a reach~~the catchment, ~~channel or swale ~~whole contributing drainage area (usually in m<sup>2</sup>).

;~~m~~A<sub>i</sub> :~~run ~~Area of ~~side slopes in channel cross sections ~~impervious cover within the catchment (~~length, but ~~usually ~~expressed as a ratio ~~in ~~relation to rise. e.g. where side side slopes = 1:3.5, ~~m ~~= 3~~<sup>2</sup>).~~5)~~

;~~q~~A<sub>p</sub> :~~infiltration rate in ~~Area of the practice e.g. footprint area of a bioretention cell (~~length per time, ~~usually ~~mm~~in m<sup>2</~~hr) (before or after application of safety factor?~~sup>)

;~~R<sub>a</sub> ~~D :~~Existing rise ~~Duration of ~~swale gradient ~~the design storm event (~~length~~in units of time, usually ~~m~~hrs)

;~~R~~d<sub>~~b~~p</sub> :~~Rise ~~Surface ponding depth of ~~compensation gradient for ~~an ~~enhanced swale ~~infiltration practice (unit of length, usually ~~m~~mm or cm)

;~~SCF~~d<sub>m</sub> :~~Safety correction factor ~~Filter media depth of a bioretention, stormwater planter or soil cell practice (~~dimensionless~~unit of length, usually mm or cm)

;d<sub>s</sub> :Storage reservoir depth of an infiltration 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) ;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 ;Q<sub>p</sub> :Peak flow in units of volume per time (e.g. m<sup>3</sup>/s) ;R :Ratio of catchment impervious area (A<sub>i</sub>) to the practice permeable footprint area (A<sub>p</sub>). ''syn.'' I/P ratio. For [[green roofs]] and often [[permeable paving]] systems that do not receive drainage from external impervious areas this will be 0. For [[bioretention]], [[infiltration trenches]] and [[infiltration chambers]] receiving pavement runoff, it is recommended to be kept between 15 to 20. ;R<sub>a</sub> :Existing rise of swale gradient (length, usually m) ;R<sub>b</sub> :Rise of compensation gradient for an enhanced swale (length, usually m) ;RVC<sub>T</sub> :Runoff volume control target (as outlined by MECP, units are mm) ;S<sub>0</sub> :Longitudinal slope (m/m, i.e. dimensionless) ;S<sub>T</sub> :Storage (m<sup>3</sup>) ;S<sub>x</sub> :Cross slope (m/m, i.e. dimensionless) ;SCF :Safety correction factor (dimensionless) ;t :Drainage time (usually in hrs) ;T :Temperature (°C) ;V :Volume (usually in m<sup>3</sup>) ;x :Perimeter of infiltration practice or swale x-section (m) ;y:Depth of water (~~length~~L, usually m or sometimes mm)