Groundwater is water that has collected within porous material beneath the ground surface
FAQs Groundwater Hydrogeology in WA
Please find below a list of Frequently Asked Questions relating to Groundwater Hydrogeology in WA:
Groundwater is water that has collected within porous material beneath the ground surface
Surface water occurs on the ground surface in rivers, creeks, lakes, wetlands etc. Groundwater is present beneath the ground surface, where it has accumulated within porous or fractured aquifers due to infiltration from the ground surface.
An aquifer is any porous or fractured material which may either contain or transmit groundwater in ‘significant’ quantities (see aquitard).
An aquitard is any material which does not permit groundwater to flow through it in any ‘significant’ quantity, usually due to a low permeability and/ or thickness (e.g. clay, shale etc).
Aquifers are recharged through rainfall, surface water or river flow and infiltration, or artificially by reinjection to bores or infiltration through ponds.
Artesian water is groundwater under pressure within a confined aquifer that will naturally flow upward in a bore, and may even reach the ground surface.
Incidental rainfall occurring over a surface area which is able to infiltrate to an underlying aquifer is called a recharge zone. At distance from the recharge zone the aquifer may become confined due to overlying low permeability formations. Artesian conditions, where the confined water is under pressure develops due to the difference in elevation between the aquifer and the recharge zone. If the pressure head within the aquifer is higher than the ground elevation, then groundwater will flow to the surface.
Incidental rainfall may run-off (to surface water courses/ drains etc) or be lost by evaporation/ transpiration (consumed by vegetation), or may infiltrate the ground surface through seepage via pores (e.g. sand), solution cavities (e.g. limestone) or fractures (e.g. basalt). Water seepage passes through the unsaturated (vadose) zone to reach the water table (saturated zone) as recharge water, which may develop within an aquifer formation. A surface area which conveys water to an aquifer is called a recharge zone.
A Hydrogeologist studies the occurrence, movement, quantity and quality of groundwater. They may for instance establish whether a sustainable groundwater resource is available for abstraction, whether the quality is good enough for a specific purpose (e.g. raw drinking water), how to reduce the groundwater level to allow mining (dewatering), whether groundwater has become contaminated and may be unfit for abstraction or may damage a surface water course by discharge, or whether material storage (e.g. tailings dams) may impact on groundwater quality et al.
The movement of contaminants in groundwater is an important way by which contaminants may move (or ‘vector’) from one site to impact on another site/ water course/ abstraction, and hence potentially impact on the environment or human health (through consumption).
In a variety of ways, for instance by spillage or leakage of contaminants on the ground surface infiltrating to the water table, by leaking underground tanks or pipes, by rainwater leaching through waste or chemical fill, effluent disposal, leachate from landfill sites etc.
Several factors influence the discharge of contaminated water to groundwater such as the depth to groundwater, the direction of groundwater flow, the type of soil, the flow rate of contaminated groundwater etc.
ASR is the artificial recharge of groundwater via re-injection in bores or re-infiltration from e.g. a lagoon, with the intention of recovering the water at a later time by abstraction. It allows excess or treated water to be stored during plentiful times (e.g. during the ‘wet’), for subsequent re-abstraction during dry or high demand periods.
Yes- within proclaimed groundwater and surface water areas, or in artesian areas.
A license is required within proclaimed groundwater and surface water areas, or to take artesian water. It is not required in non-proclaimed areas, or to take from surface water abstractions for stock or domestic purposes (riparian rights), from lakes on a single property, or from springs remote from a watercourse.
The cost is very much dependant on the nature and type of aquifer, the depth to groundwater, the selected drilling method, the bore construction and the number of bores required to provide the required flow rate, and generally increases with greater complexity & difficulty. A license to both explore for and abstract groundwater will also be required.
Deep bores are drilled into deeper aquifers or shallow bores are drilled to unconfined/sandy aquifers. Groundwater is then pumped to the surface for collection, treatment and/or distribution.
Properties which have direct contact with a watercourse or wetland have the right to take water for domestic and stock purposes.
An area proclaimed under section 26B of the Rights in Water & Irrigation Act, 1914, as a Public Drinking Water Supply Area (PDWSA); there are in excess of 150 proclaimed areas throughout Western Australia.
The Department of Health advises that untreated (raw) groundwater or surface water should not be drunk, since it may contain natural bacteria or chemicals at undesirable concentrations. DoH has published a guideline on the suitabity of raw groundwater for a variety of uses, including irrigation, vegetable growing etc (
) A A sample of groundwater should be taken and submitted to a laboratory, which should be advised of the intended use, and will then analyse it and advise you of the suitability of the water for the purpose.
A controlled abstraction from a bore, measuring the lowering of the water table over time, can be interpreted to provide hydraulic parameters for the aquifer, including permeability, transmissivity and storativity, and hence assess the sustainable yield of the bore.
Water that is fit to drink, as a minimum fresh water (i.e. Total Dissolved Solids (TDS) <1,000mg/L). However, the Department of Health advises that untreated (raw) groundwater or surface water should not be drunk, since it may contain natural bacteria or chemicals at undesirable concentrations. The Australian Drinking Water Guideline 2014 V3 lists acceptable maximum concentrations for a variety of chemicals. Drinking water should be free of bacteria and viruses.
[/toggle][toggle title=”What should I do if I get drinking water from my own bore?”]You need to ensure that the water is safe to drink. The Australian Drinking Water Guidelines 2004http://www.nhmrc.gov.au/publications/synopses/eh19syn.htm#compprovides advice on the sampling frequency and analysis for small water supplies (Ch4), and health and aesthetic guideline values against which to asses the analysis results. Advice regarding sampling and analysis can be obtained from the Department of Water/ Department of Health/ Consultants/ Laboratories. It should be noted however that the Department of Health does not recommend the use of untreated groundwater for drinking purposes.
Raw (untreated) water can come from groundwater (from bores) or from surface water (e.g. rivers). In WA, during 2008 the (treated) total scheme water supply was approximately 280Gl/yr, of which groundwater provided 48%, surface water sources 34%, and desalination (from the Kwinana plant) provided approximately 18%.
Treated drinking water may contain small amounts of contaminants; provided your water analyses are below health and aesthetic (e.g. appearance/ odour) guideline values provided in the Australian Drinking Water Guidelines 2014 V3 http://www.nhmrc.gov.au/publications/synopses/eh19syn.htm#comp, then there should be no significant heath risk. Further advice can be obtained from the Department of Water (http://www.water.wa.gov.au) / Department of Health (http://www.health.wa.gov.au/home) / Consultants/ Laboratories
The Australian Drinking Water Guidelines 2004http://www.nhmrc.gov.au/publications/synopses/eh19syn.htm#compprovides aesthetic (and health based) guideline values against which to assess the analysis results. Typically tap water may be cloudy (usually aerated) or chlorinated/ contain aluminium/ carbon dioxide (water treatment), or chlorinated compounds/ trihalomethanes (water treatment by-products evidenced by colour), be hard (calcium /magnesium salts making soap hard to lather), contain excess sodium (taste) or iron/ zinc (naturally or from pipelines), or locally be high in Total Dissolved Solids (<1000mg/L). If you have any concerns you should contact the Department of Health (http://www.health.wa.gov.au/home) or the Water Corporation (http://www.watercorporation.com.au).
The Australian Drinking Water Guidelines 2004http://www.nhmrc.gov.au/publications/synopses/eh19syn.htm#compprovide health and aesthetic guideline values, which a water supplier (e.g. Water Corporation) must comply with.
Raw (untreated) water is treated to comply with health and aesthetic (e.g. appearance/ odour) guideline values provided in the Australian Drinking Water Guidelines 2004http://www.nhmrc.gov.au/publications/synopses/eh19syn.htm#comp. Treatment processes can include et al filtration (to remove particulates), flocculation (to remove suspended particles) and chlorination (to kill bacteria and viruses), and chemical additives (e.g. fluoridation (for healthy teeth and bones), or to reduce corrosion of pipes etc).
The water contains Hydrogen Sulfide (H2S) from sulfate reducing bacteria, from hydrolysis of sulfide in anoxic conditions, from organic matter or from pyritic minerals. The Australian Drinking Water Guidelines do not specify a health guidelines, although the aesthetic (odour) guideline value is 0.05mg/L.
Salt naturally present within sediments may be mobilised by the increased infiltration of surface water due to clearing of vegetation reducing evapotranspiration rates. This may be manifested as rising saline water tables, or in saline groundwater discharges as springs or seeps causing salt ‘scalds’.
Fresh: <1,000mg/L Total Dissolved Solids (TDS), or <c1,470us cm=”” electrical=”” conductivity=”” (ec),=”” potentially=”” potable=”” water<br=””>Transitional: >1,000 to 2,000mg/L TDS (>c1,470 to c2,940 uS/cm EC)
Brackish: >2,000 to 14,000mg/L TDS (>c2,940 to c20,500uS/cm EC)
Saline: >c14,000 to 35,000mg/L TDS (>c20,500 to 51,470uS/cm EC); seawater is approximately 35,000mg/L
Hypersaline: >35,000 to 100,000mg/L TDS (>c51,470 to c147,000uS/cm EC); some groundwater in e.g. the goldfields
Brine: >100,000mg/L TDS (>c147,000uS/cm); rarely encountered, associated with e.g. evaporite deposits
In WA, the Department of Water is the government regulator and administers the Rights in Water and Irrigation Act, which licenses water abstraction. The Water Corporation (including AqWest) is the public water undertaker.
The Rights in Water and Irrigation Act; it provides for the management of water resources (i.e. licensing), its sustainable use, the protection of ecosystems, and the fostering of community consultation. It defines prohibited & authorised water taking, it defines the powers of the DoW, licensing regulations, and transferable water entitlements.
Under Statewide Policy No.5, existing licensed water allocations may transfer all or part of a license to provide for higher value uses, accommodate new water users and the more efficient use of water. Ecological water requirements are not transferable.
Under Statewide Policy No.11, 2003, existing licenses within groundwater areas which are fully or over-allocated may be re-couped to provide for new water users. Savings due to increased efficiency will not generally be recouped, nor where a license holder can provide extenuating circumstances, such as ramped production up to allocated volumes in the future. Any recouping would generally occur at license renewal.
Under ‘Policy on Accessing the L & Y Aquifers in Perth, 2006’ ‘no long-term licenses for accessing the fresh groundwater resources… of the L& Y aquifers are to be granted… other than for extenuating circumstances…’, since both aquifers are considered to be stressed.
1g/L (gram per litre) = 0.1%. 1mg/L (milligrams per litre) = 1ppm (parts per million), or 0.0001%. 1µg/L (micrograms per litre) = 1ppt (parts per trillion), or 0.0000001%.
Hard water (>121mg/L CaCO3) contains high concentrations of calcium and magnesium which react with the soap to produce a scum residue which is difficult to wash off, and also makes it difficult to obtain a soap lather. Conversely soft water (<80mg/L CaCO3) typically from hard rock aquifers) contains little Ca/Mg and hence more water is required to wash off the soap.
FAQs Groundwater Hydrogeology in WA
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