FAQs

What do these terms mean?

Biodiversity
“Biological diversity is the variety of all life forms – the different plants, animals and micro organisms, the genes they contain, and the ecosystems of which they form a part” (Commonwealth of Australia 1996). Usually three levels of biodiversity are considered – genetic, species and ecosystem diversity. Genetic diversity refers to the genetic information contained in the genes of all living things. Species diversity refers to the variety of all species. Ecosystem diversity is the variety of habitats, living communities and ecological processes.

Bioretention pond
A biorentention pond is very similar to a rain garden except that it also collects and ponds stormwater before filtering. A bioretention pond, like a rain garden, is an engineered and landscaped feature often with native plants.

Catchment
A catchment refers to an area of land which “catches” rainfall that drains to one creek or river system. Catchments provide the source of water for the dams and reservoirs in which our drinking water is collected.

Cooks River Foreshore Working Group
This is a voluntary association of foreshore and catchment councils (eight (8) of thirteen (13) councils) and various State Government agencies working collaboratively to improve, restore and revitalise the Cooks River, its foreshore and catchment environments. The working group commenced in 1997 and has been pivotal in driving the improvement of the Cooks River.

Greywater
Greywater is waste water from the kitchen, laundry and bathroom (but not the toilet). It usually contains soap, detergents and fats.

Gross pollutant trap (GPT)
Gross Pollutant Traps, or GPTs, are devices used to prevent large items such as take away containers, leaves, bottles and plastic bags from polluting waterways. GPTs are often used at the end of stormwater drains, to prevent gross pollutants from entering urban waterways, wetlands and beach fronts or used to prevent gross polluntants from exiting industrial areas and getting into the waterways. Pollutants such as dirt, chemicals, heavy metals and bacteria are not directly collected by the GPTs.

Groundwater
Ground water is water collecting below ground level in an aquifer or water table.

Heavy metals
This is a general term for cadmium, chromium, copper, iron, mercury, nickel, manganese, lead, zinc, arsenic and selenium. Heavy metals have ended up in many of our waterways as a result of pollution from industry. Heavy metals even at quite low concentrations, are toxic to most animals and plants.

Hydrology
Hydrology is the study of water occurrence, distribution, movement and balances in ecosystems; for example the seasonal patterns of a river’s flow.

Nutrients
Nutrients are substances such as nitrogen and phosphorus that are required for the growth of plants. Excess concentrations of these nutrients in rivers, creeks and bays can be harmful because they cause excess growth of aquatic plants such as blue green algae. Rotting blooms of algae produce unpleasant smells affect the taste of water. Additionally some species of blue green algae produce toxins. Algal blooms also have the effect of removing oxygen from water resulting in the death of aquatic fauna such as fish that need oxygen.

Overland flow
Overland flow is the flow of water over a land surface due to rain. Overland flow generally occurs when the soil is saturated and can no longer hold any more rainwater.

Permeable paving
Permeable or porous paving allows water to infiltrate into the soil below.  There are a number of different types of materials and techniques used to create permeable paving.  You can watch a resin-bound permeable paving in action here.

Pollution
Pollution is the contamination of soil, water, or air by the discharge of waste or other offensive materials. It is the presence of a contaminant to such a degree that the environment (land, water, or air) is not suitable for a particular use.

Rain garden
A rain garden is a landscaping feature that is planted with native perennial plants and is used to manage stormwater runoff from roofs, foot paths and car parks. A rain garden is constructed with specific soils and plants which allow stormwater to filter through the garden and into the stormwater system at a specific rate and that also filters out pollutants.

Run-off
Run off is rain or water, which flows from a catchment into a river, stream, lake or reservoir.

Sediment
Sand, clay, silt, pebbles and organic material deposited in water.

Sewerage
Sewerage consists of the waste water from toilets, kitchens, bathrooms and laundries. The sewerage systems consist of the pipes and fittings carrying sewage.

Sewer mining
Sewer mining is the capture and transfer of urban wastewater from the sewer network, and its subsequent treatment for reuse, usually as irrigation. There are currently several sewer mines under construction within the Sydney area that will provide irrigation for golf courses.

Stormwater
Stormwater is rainfall that runs off roofs, roads and other surfaces where it flows into gutters, streams, rivers and creeks, and eventually into the bays. This water can carry contaminants such as plastic bags, detergents, nutrients and heavy metals.

Stormwater harvesting
This is the capture of stormwater run off for reuse. It is generally on a scale larger than individual properties.

Subcatchment
A subcatchment is smaller area within a catchment that drains a specific area.

USWIM
The Urban Stormwater Integrated Management (USWIM) project is a joint research project of Monash University in Melbourne, Victoria and Marrickville Council in Sydney, NSW. This collaborative project is working with the community towards integrating water management approaches in Marrickville to incorporate Water Sensitive Urban Design (see below for definition), stormwater and rainwater harvesting, and addressing management of water quality, conservation and volume. The USWIM project has tested a new and more successful way of planning for sustainable water management in highly urban areas, and recently produced the Sustainable Water Planning Guidelines for Councils. The Cooks River Sustainability Initiative is based on this project and will apply processes developed previously through the USWIM project in 6 subcatchments across the Cooks River catchment (Click here for more information).

Water Cycle
The Water cycle, also known as the hydrologic cycle, describes the continuous movement of water on, above, and below the surface of the Earth. Since the water cycle is truly a “cycle,” there is no beginning or end. Water can change states among liquid, vapour, and ice at various places in the water cycle, with these processes happening in the blink of an eye and over millions of years. Although the balance of water on Earth remains fairly constant over time, individual water molecules can come and go in a hurry. (Click here for more information and diagrams)

Water Sensitive Urban Design
Water Sensitive Urban Design (WSUD) is about the integration of water cycle management into urban planning and design. The key principles of Water Sensitive Urban Design as stated in the Urban Stormwater – Best Practice Environmental Management Guidelines (Victorian Stormwater Committee, 1999) are:

1. Protect natural systems – protect and enhance natural water systems within urban developments. Promoting and protecting natural waterways as assets allows them to function more effectively and supports the ecosystems that rely on them.
2. Integrate stormwater treatment into the landscape – use stormwater in the landscape by incorporating multiple use corridors that maximise the visual and recreational amenity of developments. The natural stormwater drainage system can be utilised for its aesthetic qualities within parklands and walking paths, making use of natural topography such as creek lines and ponding areas.
3. Protect water quality – improve the quality of water draining from urban developments into the receiving environment. Through filtration and retention, water draining from urban developments can be treated to remove pollutants close to their source. This approach reduces the effect that polluted water can have upon the environment and protects the natural waterways.
4. Reduce runoff and peak flows – reduce peak flows from urban development by local detention measures and minimising impervious areas. Local detention and retention enables effective land use for flood mitigation by utilising numerous storage points in contrast to the current practice of utilisation of large retarding basins. This approach subsequently reduces the infrastructure required downstream to effectively drain urban developments during rainfall events.
5. Add value while minimising development costs – minimise the drainage infrastructure cost of the development. The reduction of downstream drainage infrastructure due to reduced peak flows and runoff minimises the development costs for drainage, whilst enhancing natural features such as rivers and lakes that add value to the properties of the area. Click here for more information

Watershed
A watershed is the total land area that contributes water to a river, stream, lake or other body of water. Watershed is synonymous with drainage area, drainage basin and catchment.

Watertable
The watertable is the upper surface of groundwater. The soil is fully saturated below the watertable and unsaturated above it.

Wetland
Low-lying areas of land occasionally or permanently covered with either fresh or salt water. Wetlands can occur naturally and or they can be constructed.

Where is the Cooks River?
The Cooks River is a 23 kilometre long urban waterway starting at Graf Park, Yagoona then flowing in a north-west direction through to Chullora, before turning to the south-west through south Strathfield, Canterbury and Marrickville and then draining into Botany Bay at Kyeemagh.

The river’s catchment is highly urbanised and serves as part of a stormwater system for the 100 square kilometres of its watershed. From South Strathfield to Canterbury, the river is a concrete channel and many of its tributaries have also been converted to concrete or brick lined channels. The tidal sections support significant areas of mangroves, saltmarsh and bird, and fish life, and are used for recreational activities.

Why is the Cooks River so degraded?
Almost since the beginning of European settlement, the Cooks River has suffered extreme degradation. Early on the catchment was stripped of natural vegetation and since then sewage, industrial and domestic waste, stormwater pollution and rubbish dumping have caused a severe decline in water quality. Dredging and artificial channel modifications have also severely impacted on the natural landscape of the river.

Industrial pollution is no longer allowed to be be pumped into the River, however sewage overflows, rubbish and stormwater runoff continue to severly pollute the River. Further urbanisation compounded by complexities such as catchment size, population dynamics and outmoded stormwater infrastructure continue to frustrate  advances in catchment and stormwater management that would greatly improve the environmental and recreational qualities of the River.