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Glossary of Terms (view source)

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= F =
 
= F =
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=== Filter Media ===
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The engineered soil bed component of bioretention cell or dry swale designs,
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typically composed of a sandy soil mixture containing a limited proportion of fine textured
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material, which provides a growing medium for vegetation, maintains a high rate of infiltration
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over the lifespan of the practice, and retains contaminants through filtration and adsorption to
 +
soil particles.
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=== Filtration ===
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The technique of removing pollutants from runoff as it infiltrates through the soil.
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=== Fines ===
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Soil materials with less than a 0.050 mm diameter particle size.
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=== First Flush ===
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Initial pulse of stormwater runoff which picks up the pollutants that have settled on
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surfaces during the dry period. The first flush contains the highest pollutant concentrations.
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=== Forebay ===
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A pretreatment basin at the inlet of a practice that allow settling out of sediment and
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associated contaminants suspended in urban runoff.
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 +
=== Flow Path Length ===
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The minimum linear distance of water flow across a surface.
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=== Fluvial Geomorphology ===
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The study of the processes responsible for the shape and form, or
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morphology, of watercourses; describes the processes whereby sediment (e.g., silt, sand,
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gravel) and water are transported from the headwaters of a watershed to its mouth.
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 +
=== Fused Grid ===
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A hybrid neighbourhood and district layout model that combines the geometries of
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inner city grid road patterns with the loop and cul-de-sac road patterns of conventional suburbs.
    
= G =
 
= G =
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=== Grass Swales ===
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Vegetated, open channels designed to convey, treat and attenuate runoff.
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Design variations range from simple grass channels, which are designed primarily for
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conveyance to more complex treatment and volume reduction designs like enhanced grass
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swales, and dry swales or bioswales.
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 +
=== Geotextile ===
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A filter fabric that is installed to separate dissimilar soils and provide runoff filtration
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and contaminant removal benefits while maintaining a suitable rate of flow; may be used to
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prevent fine-textured soil from entering a coarse granular bed, or to prevent coarse granular
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from being compressed into underlying finer-textured soils.
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 +
=== Granular ===
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Gravel, or crushed stone of various size gradations (i.e., diameter), used in
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construction; void forming material used as bedding and runoff storage reservoirs and
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underdrains in stormwater infiltration practices.
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 +
=== Gravel Diaphragm ===
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Is a level spreading device placed at a runoff discharge location,
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perpendicular to flow, to maintain sheet flow and distribute runoff as evenly as possible across a
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pervious area or stormwater infiltration practice. A gravel diaphragm acts as a pretreatment
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device, settling out suspended sediments before they reach the practice.
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 +
=== Green Roof ===
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A thin layer of vegetation and growing medium installed on top of a conventional
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flat or sloped roof, also referred to as living roofs or rooftop gardens.
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 +
=== Green Infrastructure ===
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Natural vegetation and vegetative technologies in urban settings such as:
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urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community
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gardens; natural and engineered wetlands and stormwater management ponds; and porous
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pavement systems. These systems are designed to provide multiple benefits, such as moderate
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temperatures, clean air and water, and improve aesthetics.
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 +
=== Groundwater Discharge ===
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The outflow of groundwater to a well, spring, wetland or watercourse.
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=== Groundwater Recharge ===
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The inflow of surface water to a groundwater reservoir or aquifer.
    
= H =
 
= H =
 +
=== Hydraulic Conductivity ===
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A parameter that describes the capability of a medium to transmit water.
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=== Hydrologic Cycle ===
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The circulation of water from the atmosphere to the earth and back, through
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precipitation, runoff, infiltration, groundwater flow and evapotranspiration.
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=== Hydrologic Regime ===
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The characteristic pattern of precipitation, runoff, infiltration and evaporation
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affecting the hydrology of a system.
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=== Hydrologic Soil Groups ===
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A soil classification system based on the ability to convey and store
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water; divided into four groups:
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A – well drained sands and gravel, high infiltration capacity, high leaching potential and low
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runoff potential;
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B – Moderately drained fine to coarse grained soils, moderate infiltration capacity, moderate
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leaching potential and moderate runoff potential;
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C – Fine grained, low infiltration capacity, low leaching potential and high runoff potential;
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D – Clay soils, very low infiltration capacity, very low leaching potential and very high runoff
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potential.
    
= I =
 
= I =
 +
=== Impervious ===
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A hard surface area (e.g., road, parking area or rooftop) that prevents or retards
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the infiltration of water into the soil.
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=== Infiltration ===
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Penetration of water through the ground surface.
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=== Inline ===
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Refers to a system that accepts all of the flow from a drainage area and conveys larger
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event flows through an overflow outlet.
    
= J =
 
= J =
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= L =
 
= L =
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=== Landform ===
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The natural features of the landscape, dictates flow patterns, runoff velocities and
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discharge rates.
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=== Landscape-based Approach ===
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The principle that development form, servicing and stormwater
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management strategies should be defined by the biophysical, hydrological and ecological
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attributes of the landscape.
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=== Lot Level ===
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The treatment of urban runoff as close to the source area as possible through
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application of small scale stormwater management practices on individual properties that are
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linked to downstream conveyance and end-of-pipe practices.
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=== Low Impact Development ===
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A stormwater management strategy that seeks to mitigate the
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impacts of increased urban runoff and stormwater pollution by managing it as close to its source
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as possible. It comprises a set of site design approaches and small scale stormwater
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management practices that promote the use of natural systems for infiltration and
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evapotranspiration, and rainwater harvesting.
    
= M =
 
= M =
 +
=== Master Environmental Servicing Plan (MESP) ===
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Is a community-scale planning assessment of
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servicing and environmental considerations for a development project.
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 +
=== Mulch ===
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Shredded woody material or leaf compost used as a top dressing over vegetation beds
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that provides a source of soil nutrients and helps retain soil moisture; in bioretention cells and
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dry swales the surface mulch layer provides pollutant removal and improves growing conditions
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for the selected plants; shredded hardwood bark has been found to work best as it is less likely
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to float.
    
= N =
 
= N =
 +
=== Native Soil ===
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The natural ground material characteristic of or existing by virtue of geographic
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origin.
    
= O =
 
= O =
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=== Offline ===
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Refers to a system that when full, stormwater will bypass the practice. Offline systems
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use flow splitters or bypass channels that only allow the water quality volume to enter the
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facility. This may be achieved with a pipe, weir, or curb opening sized for the target flow, but in
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conjunction, create a bypass channel so that higher flows do not pass over the surface of the
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filter bed.
    
= P =
 
= P =
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=== Permeable Pavement ===
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Is an alternative practice to traditional impervious pavement, prevents
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the generation of runoff by allowing precipitation falling on the surface to infiltrate through the
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surface course into an underlying stone reservoir and, where suitable conditions exist, into the
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native soil.
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=== Physiography ===
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The physical features of the land, including topography, morphology and
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geologic origin. The physical feature of the land has an influence on the surface water
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movement and the interactions between surface water and groundwater.
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=== Pollution Hot Spot ===
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areas where certain land uses or activities have the potential to generate
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highly contaminated runoff (e.g., vehicle fuelling, service or demolition areas, outdoor storage
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and handling areas for hazardous materials and some heavy industry sites).
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 +
=== Pollutant Load ===
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The total mass of a pollutant entering a waterbody over a defined time period.
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=== Predevelopment ===
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refers to the characteristics and functions of a system prior to urban
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development.
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=== Pretreatment ===
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Initial capturing and removal of unwanted contaminants, such as debris,
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sediment, leaves and pollutants, from stormwater before reaching a best management practice;
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Examples include, settling forebays, vegetated filter strips and gravel diaphragms.
    
= Q =
 
= Q =
    
= R =
 
= R =
 +
=== Rain Garden ===
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A lot level bioretention cell designed to receive and detain, infiltrate and filter
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runoff, typically used for discharge from roof leaders.
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=== Rainwater Harvesting ===
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Is the practice of intercepting, conveying and storing rainwater for future
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use. The captured rainwater is typically used for outdoor non-potable water uses such as
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irrigation and pressure washing, or in the building to flush toilets or urinals or other uses that do
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not require potable water.
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=== Recharge ===
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The infiltration and movement of surface water into the soil, past the vegetation root
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zone, to the zone of saturation or water table.
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=== Riparian ===
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A vegetated ecosystem alongside a waterbody, characteristically have a high water
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table and are subject to periodic flooding.
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=== Runoff ===
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Water from rain, snow melt, or irrigation that flows over the land surface.
    
= S =
 
= S =
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=== Sedimentation ===
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Settling-out or deposition of particulate matter suspended in runoff.
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 +
=== Soakaway ===
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An excavated area lined with geotextile filter cloth and filled with clean granular
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stone or other void forming material, that receives runoff and allow it to infiltrate into the native
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soil; can also be referred to as infiltration galleries, French drains, dry wells or soakaway pits.
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=== Soil Amendment ===
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The practice of adding organic material, such as mulch or compost to topsoil
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to improve fertility, and tilling of the native soils to reverse compaction and restore its water
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retaining capacity.
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=== Standing Water ===
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Water ponded on the ground surface.
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=== Stone Reservoir ===
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An underlying aggregate material bed that temporarily stores stormwater
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before infiltrating into the native soil or being conveyed by an underdrain pipe.
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=== Stormwater Planer ===
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A bioretention cell that features an imperveable liner that collects and
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treats stormwater through sedimentation and filtration only (i.e., no infiltration).
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 +
=== Stream Channel ===
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A natural waterway, formed by fluvial processes, that conveys running water.
    
= T =
 
= T =
 +
=== Treatment Train Approach ===
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A combination of lot level, conveyance, and end-of-pipe stormwater
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management practices.
    
= U =
 
= U =
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=== Underdrain ===
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A perforated pipe used to assist the draining of soils.
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 +
=== Urbanization ===
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The changing of land cover and land uses from rural to urban; the growth of
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urban settlements.
    
= V =
 
= V =
 +
=== Vegetated Filter Strip ===
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Are gently sloping, densely vegetated areas that treat runoff as sheet flow
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from adjacent impervious areas. They function by slowing runoff velocity and filtering out
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suspended sediment and associated pollutants, and by providing some infiltration into
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underlying soils. Also known as buffer strips and grassed filter strips.
    
= W =
 
= W =
 +
=== Water Balance ===
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The accounting of inflow and outflow of water in a system according to the
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components of the hydrologic cycle.
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 +
=== Water Cycle ===
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The continuous movement of water from the oceans to the atmosphere (by
 +
evaporation), from the atmosphere to the land by condensation and precipitation, and from the land
 +
back to the sea (via groundwater and stream flow); also referred to as hydrologic cycle.
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 +
=== Water Budget ===
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The mathematical expression of the water balance.
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 +
=== Water Quality Volume ===
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The amount of stormwater runoff from a given area required to be
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retained by stormwater management practices to reduce pollutant load to an acceptable level.
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 +
=== Water Table ===
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Subsurface water level which is defined by the level below which all the spaces in
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the soil are filled with water; The entire region below the water table is called the saturated
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zone.
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 +
=== Watershed ===
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An area of land that drains into a river or a lake. The boundary of a watershed is
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based on the elevation (natural contours) of a landscape.
    
= X =
 
= X =
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