Glossary

This glossary is copied from the Stormwater Manual of Western Australia Chapter 11: Further Information. References are available from this chapter.

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

S

Sand: A soil separate consisting of particles between 0.02 and 2.0 mm in equivalent diameter. Fine sand is defined as particles between 0.02 and 0.2 mm, and coarse sand as those between 0.2 and 2.0 mm. (Charman & Murphy 1991.)

Sediment: Solid fragment of organic and inorganic material that is transported, suspended and/or deposited by water and wind.

Sedimentation: The physical process of settling of suspended particulates under the force of gravity (ARMCANZ & ANZECC 2000).

Sediment trap: A structure designed to intercept and retain sediment transported by water flow (ARMCANZ & ANZECC 2000).

Silt: A soil separate consisting of particles between 0.002 and 0.02 mm in equivalent diameter (Charman & Murphy 1991).

Social/cultural values: Social values include public health and safety, recreational uses and visual amenity. Cultural values include historical and spiritual significance, and scientific and educational uses.

Sodic soils: Soil sodicity is assessed by the ratings of the exchangeable sodium percentage (ESP). Soils with a relatively high proportion of exchangeable sodium (greater than 6 per cent) are considered sodic (Charman & Murphy 1991). Soil sodicity causes increased soil dispersion and swelling of clays, which adversely impacts the soil structure and results in reduced infiltration, reduced hydraulic conductivity and the formation of surface crusts.

Soil amendment: Involves adding an agent, such as clay or crushed limestone, to the soil to improve its structure, porosity, water holding capacity and nutrient recycling capacity.

Soil permeability: The ease with which gases, liquids or plant roots penetrate or pass through a layer of soil.

Soil stabilisation: The use of measures or materials, such as rock lining or vegetation, to prevent the movement of soil when loads are applied to the soil.

Source controls: Non-structural or structural best management practices designed to minimise the generation of excessive stormwater runoff and/or pollution of stormwater at or near the source and protect receiving environments.

Stormwater: Water flowing over ground surfaces and in natural streams and drains, as a direct result of rainfall over a catchment. Stormwater consists of rainfall runoff and any material (soluble or insoluble) mobilised in its path of flow.

Stormwater quality: The chemical, physical and biological characteristics of stormwater.

Stormwater quantity: The volume characteristics of stormwater.

Strategic planning and institutional controls: One of the five principal categories of non-structural BMPs for stormwater management. Examples include controls such as the use of strategic, regional or citywide urban stormwater management plans and stable funding arrangements to support the implementation of these plans.

Street sweeping: The removal of particulates and litter from street surfaces by sweeping or vacuuming (ARMCANZ & ANZECC 2000).

Structural controls: Engineered devices implemented to manage runoff quality and quantity, to control, treat, or prevent stormwater pollution and/or reduce the volume of stormwater requiring management.

Sub-catchment: A topographically defined area drained by a tributary of a primary stream (ARMCANZ & ANZECC 2000).

Subsurface drain: A drain designed to intercept subsoil water and thereby limit the seasonal maximum groundwater level.

Superficial (unconfined) aquifer: An aquifer containing water with no upper non-porous layer to limit its volume or to exert pressure. The upper surface of the groundwater within the aquifer is called the watertable.

Surface water: Water flowing or held in waterways or wetlands on the surface of the landscape (adapted from Water and Rivers Commission 2000a).

Suspended solids: Organic or inorganic particles that are suspended and transported by water. This includes sand, mud and clay particles (and associated contaminants) in stormwater.

Swale: A drainage interception and conveyance system with relatively gentle side slopes and shallow flow depths.

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