Australian Water Information Dictionary

Water data: National Atlas of Groundwater Dependent Ecosystems

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An underground layer of saturated rock, sand or gravel that absorbs water and allows it free passage through pore spaces.

Source: Australian and New Zealand Guidelines for Fresh and Marine Water Quality (2000)

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The component of streamflow supplied by groundwater discharge.

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The zone of soil moisture above the watertable where water is drawn upwards by capillary tension in which the water is at less than atmospheric pressure.

Source: Richardson, S., et al., (2011). Australian groundwater-dependent ecosystem toolbox part 1: assessment framework, Waterlines report, National Water Commission, Canberra

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Documentation of a conceptual understanding of the location of GDEs and interaction between ecosystems and groundwater.

Source: Richardson, S., et al., (2011). Australian groundwater-dependent ecosystem toolbox part 1: assessment framework, Waterlines report, National Water Commission, Canberra

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An aquifer overlain by a confining bed. The confining bed has a significantly lower hydraulic conductivity than the aquifer. Typically groundwater in a confined aquifer is under pressure significantly greater than atmospheric pressure.

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electrical conductivity

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A region where similar processes determine the interaction between groundwater and ecosystems, due to similar ecology, geology, climate, and groundwater/surface water connections.

Related: EHZ

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Description of the water regimes needed to sustain the ecological values of water-dependent ecosystems at a low level of risk.

Source: adapted from definition for Environmental Water Requirements in ARMCANZ & ANZECC 1996, National principles for the provision of water for ecosystems, Sustainable Land and Water Resources Management Committee Subcommittee on Water Resources Occasional Paper SWR No 3 July 1996

Related: EWR

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A dynamic complex of plant, animal and micro-organism communities and their non-living environment interacting as a functional unit.

Source: Commonwealth Environmental Protection and Biodiversity Conservation Act 1999

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eco-hydrogeological zone

Related: eco-hydrogeological zone

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Electrical conductivity (EC) measures dissolved salt in water. The standard EC unit is microSiemens per centimetre (µS/cm) at 25 °C.

Source: National Water Commission Water Dictionary

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The combined loss of water from a given area during a specified period of time by evaporation from the soil or water surface and by transpiration from plants.

Source: Australian and New Zealand Guidelines for Fresh and Marine Water Quality (2000)

Synonym: evapotranspiration

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ecological water requirement

Related: ecological water requirement

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A stream where groundwater discharge contributes to streamflow.

Source: Richardson, S., et al., (2011). Australian groundwater-dependent ecosystem toolbox part 1: assessment framework, Waterlines report, National Water Commission, Canberra

Synonym: discharge from groundwater to surface water

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groundwater dependent ecosystem

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Describes ecosystems in terms of their 'potential to be interacting with groundwater'. The classes mapped in the GDE Atlas are:

The term 'potential' is used to reflect the uncertainty inherent in identifying ecosystems as groundwater-dependant using remote analysis methods. Finer scale studies or fieldwork are needed to confirm this analysis.

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Describes GDEs within the Atlas that were identified through desktop analysis in previous studies.

Since the result for these GDEs was not derived during the GDE Atlas analysis, no GDE potential result could be applied to these ecosystems. This also means no ‘Lines of Evidence’ attribute is necessary. However, it is considered that the identification of these ecosystems as GDEs is relatively reliable, since previous studies have usually focussed on smaller areas than the Atlas, and have been able to analyse the potential interaction between ecosystems and groundwater in more detail.

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Describes GDEs within the Atlas that were identified through fieldwork.

These GDEs do not have ‘GDE potential’ or ‘Lines of Evidence’ attributes because they were identified through fieldwork (rather than using the GDE Atlas methodology). The identification of these ecosystems as GDEs is considered to be very reliable.

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groundwater flow system

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(a) water occurring naturally below ground level (whether in an aquifer or otherwise) or (b) water occurring at a place below ground that has been pumped, diverted or released to that place for the purpose of being stored there. It does not include water held in underground tanks, pipes or other works.

In GDE Atlas, this definition includes the capillary fringe, which is an important source of water for many GDEs.

Source: Water Act 2007 Part 1 Section 4

Equivalent: water market equivalent terms

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Natural ecosystems that require access to groundwater to meet all or some of their water requirements on a permanent or intermittent basis, so as to maintain their communities of plants and animals, ecosystem processes and ecosystem services.

Source: Richardson, S., et al., (2011). Australian groundwater-dependent ecosystem toolbox part 1: assessment framework, Waterlines report, National Water Commission, Canberra

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The system which represents the movement of subsurface water from the point where it enters the ground to where it leaves.

Source: Richardson, S., et al., (2011). Australian groundwater-dependent ecosystem toolbox part 1: assessment framework, Waterlines report, National Water Commission, Canberra

Related: groundwater flow

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GDE Atlas terminology used to classify ecosystems as likely to be interacting with groundwater. It indicates that groundwater is likely to be present, and the ecosystem is likely to be using it. This categorisation means that the majority of data analysed indicated a high potential for groundwater interaction, or that the most reliable (and most heavily weighted) datasets indicated high potential.

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A property of soil or rock, which describes the ease with which water can move through pore spaces or fractures. It depends on the intrinsic permeability of the material and on the degree of saturation. Saturated hydraulic conductivity describes water movement through saturated media.

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inflow dependence

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Inflow Dependent Ecosystem

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Describes a landscape within the GDE Atlas that is wetter than surrounding areas either seasonally or permanently, because it receives water from inflows in addition to rainfall. IDs include groundwater dependent ecosystems as well as ecosystems which use sources of water other than rainfall (e.g. surface water, soil water, irrigation).

The layer that shows IDs is derived from the remote sensing layer, in which only pixels that have inflow dependence likelihoods of between 6 and 10 are included. The pixels are a combination of MODIS and Landsat data and are at a resolution of 25m2.

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Describes the likelihood that a landscape is accessing a source of water in addition to rainfall (that it is inflow dependent). It is expressed in the ID layer as a value between 6 (low) and 10 (high), where 10 indicates a landscape that is most likely to be accessing additional water sources. A likelihood value of 6 indicates a landscape that is marginally more likely to be accessing an additional source of water than relying solely on rainfall. A value of less than 6 represents a landscape that is more likely to rely solely on rainfall and is therefore not considered inflow dependent.

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Describes ecosystems that are likely to be using another source of water in addition to rainfall. IDEs include groundwater dependent ecosystems as well as ecosystems which use sources of water other than rainfall (e.g. surface water, soil water, irrigation).

IDEs are effectively the ID pixels assigned onto a previously mapped ecosystem polygon. The pixel ID likelihood value was assigned to each ecosystem polygon using a majority rules approach. This means that the ID likelihood value which occurred most often within the ecosystem polygon, was the likelihood value assigned to the polygon overall.

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Terrain characterised by sinkholes, caves and springs, developed most commonly in carbonate rocks, where significant dissolution of the rock has occurred due to flowing water.

Source: Jennings 1985; Culver et al. 1995; Fetter 2001 as referenced in M Tomlinson and A Boulton 2008, Subsurface groundwater dependent ecosystems: a review of biodiversity, ecological processes and ecosystem services, National Water Commission Waterlines Occasional Paper No. 8, October 2008

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Landsat Thematic Mapper 5 – a medium resolution satellite image sensor obtained twice monthly over Australia. Data can be obtained from United States Geological Survey.

Source: Engel, J., and Weinstein, O., (1983). The Thematic Mapper – an overview, IEEE Transactions On Geoscience and Remote Sensing, GE-21:258-265

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GDE Atlas terminology identifying the number of rules that could be applied to a polygon given the GIS data available for the analysis. The ‘Lines of Evidence’ result shows how much data the GDE potential result was based on, and therefore is a pragmatic indicator of the reliability of the GDE potential result. This is an attribute for each derived GDE polygon.

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A stream from which water is lost to the surrounding and underlying substrate via infiltration through the streambed and banks.

Source: Richardson, S., et al., (2011). Australian groundwater-dependent ecosystem toolbox part 1: assessment framework, Waterlines report, National Water Commission, Canberra

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GDE Atlas terminology used to classify ecosystems as unlikely to be interacting with groundwater. It indicates that groundwater is unlikely to be present, or if it is present, the ecosystem is unlikely to use it. This categorisation means that all datasets suggest groundwater interaction is unlikely, or that the most reliable (and most heavily weighted) datasets suggest that groundwater interaction is unlikely.

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Expresses the estimated mean seasonal range in the amount of water stored in all water stores (surface, soil and groundwater). A large range is likely to indicate a large use of water from storage during periods with low rainfall, for example through root water uptake from deeper soil or groundwater stores.

Source: Van Dijk, A., Warren, G., Van Niel, T., Byrne, G., Pollock. D., Doody, T., (2011). Derivation of data layers from medium resolution remote sensing to support mapping of groundwater dependent ecosystems. CSIRO Land and Water, Internal Document for National Water Commission GDE Atlas.

Related: MSSR

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GDE Atlas terminology used to classify ecosystems that may interact with groundwater. It indicates that groundwater is possibly present, and the ecosystem may use it. Where data is conflicting (some data suggests that groundwater interaction is occurring, while other data suggests it is not), and it is weighted equally (both datasets are considered equally good indicators of groundwater interaction), this will be the resulting categorisation.

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MODerate resolution Imaging Spectrometer – a sensor mounted on NASA’s TERRA and AQUA satellites that orbits the Earth collecting data in visible and infrared wavelengths. The data used in this project was the MOD43B4 Nadir BRDF (NBAR) product disseminated by NASA and post-processed by CSIRO.

Source: Paget, M.J. and King, E.A., (2008). MODIS Land data sets for the Australian region. CSIRO Marine and Atmospheric Research internal report 004, CSIRO Canberra, Australia, ISBN 978192142432(pdf).

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mean seasonal storage range

Related: mean seasonal storage range

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A region in the unsaturated zone where the soil or rock may be locally saturated because it overlies a low-permeability unit.

Source: National Water Commission Water Dictionary

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Value that represents the acidity or alkalinity of an aqueous solution. It is defined as the negative logarithm of the hydrogen ion concentration of the solution.

Source: Australian and New Zealand Guidelines for Fresh and Marine Water Quality (2000)

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A surface representing the hydraulic head of groundwater; represented by the watertable altitude in an unconfined aquifer or by the altitude to which water will rise in a properly constructed well in a confined aquifer.

Source: USGS Definition of Terms

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Any kind of data recording by a sensor which measures energy emitted or reflected by objects located at some distance from the sensor (i.e. no direct ground contact). Can include aerial photographs, airborne digital sensors and satellite imagery.

Source: Richardson, S., et al., (2011). Australian groundwater-dependent ecosystem toolbox part 1: assessment framework, Waterlines report, National Water Commission, Canberra

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An area or zone within or along the banks of a stream or adjacent to a watercourse or wetland; relating to a riverbank and its environment, particularly to the vegetation.

Related: riparian zone

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The concentration of soluble salts in a solution, soil or other medium.

Source: eWater Toolkit Glossary

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The part of the lithosphere where each void space in subsurface material is filled with water, or is saturated, under greater pressure than that of the atmosphere.

Source: Poehls DJ and Smith GJ 2009, Encyclopedic dictionary of hydrogeology, Elsevier Inc., 517 pp.

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The formation of layers in a water body that show differences in temperature, turbidity, pH, nutrients, salinity, dissolved oxygen or light penetration at various depths.

Source: eWater Toolkit Glossary

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The flow of water in streams, rivers and other channels.

Synonym: flow

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Aquatic animals found in groundwater; sometimes used as a synonym of stygobite.

Source: Tomlinson M and Boulton A 2008, Subsurface groundwater dependent ecosystems: a review of biodiversity, ecological processes and ecosystem services, National Water Commission Waterlines Occasional Paper No. 8, October 2008

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A water-dependent ecosystem occurring below the surface of the ground within fractured, porous or unconsolidated aquifers, and in caves in both the saturated and vadose zones.

Source: Australian National Aquatic Ecosystem Classification, Subterranean Class – Background briefing note. Aquatic Ecosystems Task Group.

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A GDE that accesses subsurface groundwater to meet all or some of its water requirements. This includes terrestrial vegetation, subsurface fauna communities (e.g. burrowing crayfish), and some vegetation which is associated with a surface water body.

Source: Eamus, D., Froend, R., Loomes, R., Hose, G., Murray, B., (2006). A functional methodology for determining the groundwater regime needed to maintain the health of groundwater-dependent vegetation, Australian Journal of Botany, 2006, 54, 97–114, 2006.

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A GDE which uses groundwater after it has been discharged to the surface. This includes all groundwater-fed surface water bodies, such as rivers, wetlands, lakes and springs.

This definition refers only to the aquatic (inundated) component of a system, and therefore excludes any vegetation which may fringe a surface water body.

Source: Eamus, D., Froend, R., Loomes, R., Hose, G., Murray, B., (2006). A functional methodology for determining the groundwater regime needed to maintain the health of groundwater-dependent vegetation, Australian Journal of Botany, 2006, 54, 97–114, 2006.

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total dissolved solids

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The rate at which water moves through a unit width of aquifer or aquitard under a unit hydraulic gradient. It is the product of aquifer thickness and hydraulic conductivity.

Source: Richardson, S., et al., (2011). Australian groundwater-dependent ecosystem toolbox part 1: assessment framework, Waterlines report, National Water Commission, Canberra

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Evaporation loss of water from the leaves of plants through the stomata; the flow of water through plants from soil to atmosphere.

Source: eWater Toolkit Glossary

Related:

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Terrestrial animals living in caves and other air-filled subterranean spaces.

Source: Tomlinson M and Boulton A 2008, Subsurface Groundwater Dependent Ecosystems: a review of biodiversity, ecological processes and ecosystem services, National Water Commission Waterlines Occasional Paper No 8, October 2008

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In relation to a water sample, means the amount of small particles of solid matter suspended in the water sample, measured by the amount of scattering and absorption of light rays caused by the particles.

Source: Water Regulations 2008 Schedule 3 Part 1

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An aquifer in which there are no confining beds between the saturated zone and the surface. There will be a watertable in an unconfined aquifer.

Source: National Water Commission Water Dictionary

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The areas below the ground where void spaces are filled with a mixture of water under pressure less than atmospheric which includes water held by capillarity and air (gases) under atmospheric pressure.

Source: Poehls DJ and Smith GJ 2009, Encyclopedic dictionary of hydrogeology, Elsevier Inc., 517 pp.

Related: unsaturated zone

Synonym: vadose zone

This definition applies to:

The areas below the ground where void spaces are filled with a mixture of water under pressure less than atmospheric which includes water held by capillarity and air (gases) under atmospheric pressure.

Source: Poehls DJ and Smith GJ 2009, Encyclopedic dictionary of hydrogeology, Elsevier Inc., 517 pp.

Synonym: unsaturated zone

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The groundwater surface in an unconfined aquifer or confining bed at which the pore pressure is atmospheric. It can be measured by installing shallow wells extending a few meters into the saturated zone and then measuring the water level in those wells.

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Eight regions which cover Australia, where the broad rules which describe groundwater/ecosystem interaction are likely to be similar. These regions were used to implement the methodology for identifying and mapping GDEs in the development of the GDE Atlas.

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