The total groundwater resources is 30 times larger than the more familiar rivers and lakes. Worldwide, 1.5 billion people rely on groundwater for most or all of their water needs. However, despite this familiarity, groundwater is a mystery to most people who imagine underground lakes and rivers.In reality, groundwater like oil is found in the spaces between sand grains and fractures.
Groundwater movement in reality (modified from http://www.groundwater.com.au)
Groundwater Use Increasing
Due to drought and other, competing users of surface water, more and more people are turning to groundwater. However, use often exceeds groundwater recharge rates resulting in falling groundwater levels/pressure and contamination with low quality water.
What is the long term damage and cost?
Groundwater resources often span international and state borders making it a difficult to coordinate management. In addition, there are is increasing pressure on groundwater due to growth in geothermal, carbon storage, coal seam gas and petroleum industries. Groundwater resources (quantity, quality and sustainable extraction) must be assessed before undertaking sustainable regional development planning and water rights negotiations.
The FrOG Tech view of the interconnectivity of all fluids within the geofabric. Perturbation of any of these can dramatically affect the others in ways we do not currently understand. However, through improved knowledge of the geofabric these linkages can be better understood and managed.
A. Groundwater/Surface Water Interaction: Scientists have only recently begun to recognise the complex and intimate nature of groundwater and surface water connectivity. In most places water moves seamlessly from rivers into groundwater systems and back into rivers. Aquifers can be sedimentary or fractured. http://www.atsdr.cdc.gov/HAC/pha/oakridge_gw_7-06/images/gor_fb3.jpg
B. Onshore Petroleum: Over the last 25 years, there has been approximately 230 GL of groundwater co-production from the petroleum industry in Western Australia (WAPIMS). While much of this water is saline, connectivity between aquifers can affect freshwater aquifers above and below the oil reservoir. Once petroleum production has ceased, groundwater steady state conditions will be re-established over a period of hundreds to thousands of years. This change in boundary conditions could result in CO2 stored in depleted oil and gas reservoirs being remobilised. http://www.daylife.com/photo/01Xj0qY09E4Fh
C. Groundwater Fractured: In general, fractured rock aquifers are generally low yielding due to the difficulty of intercepting fractures with vertical bores. Where fractures are intercepted by horizontal structures such as mine shafts, however they can yield large volumes of water. These fractures can also carry water long distances and ultimately recharge deep sedimentary aquifers. Deep fractured aquifers are also key targets for geothermal power production. http://www.geosurvey.state.co.us/wateratlas/chapter7_5page2.asp
D. Groundwater Sedimentary Basin: Sedimentary basins can contain suitable aquifers at depths that can exceed 15,000 metres. In the deeper aquifers, water is often found in conjunction with other fluids such as petroleum. Exploitation of either can have major consequences on the other. Deep sedimentary basin are also key targets for CO2 storage. http://www.thinking50.com.au/go/create/groundwater-sources-current
E. Offshore Petroleum: FrOG Tech has developed a workflow that is designed to significantly enhance groundwater quantity and quality estimates over large areas of the world. These effects can lead to saline groundwater intrusion, land subsidence, mobilisation of CO2 and a decrease in fresh groundwater. http://petroleum.mst.edu/prospectivestudents/undergraduatedegree/pe_bachelor.html
F. Carbon Capture and Storage: Carbon capture and storage targets deep saline aquifers with the potential to hold CO2 for geologically long periods of time. If the aquifer geometry and connectivity are not understood then leakage of CO2 and high salinity groundwater can occur. Changes in equilibrium conditions due to other users could affect the security of CO2 storage. http://www.bgr.bund.de/cln_092/nn_1182122/EN/Themen/CO2-Speicherung/Bilder/faq__1__g__en.html
G. Mining: Mining uses large volume of groundwater for processing and as a by product of the mining process. Mines as deep as 4 kilometres have had difficulty in keeping groundwater from flooding the mines. Understanding the processes linking the mines to areas such as springs can help to protect important ecological and cultural sites. http://www.nmenv.state.nm.us/gwb/Pre%208-2004/images/Lac.JPG
H. Coal Seam Gas: Coal Seam Gas produces large volumes of water during the production of methane from deep coal seams. This water must then be disposed of through injection back into the aquifer or treatment and reuse. The resulting under- or over-pressuring of the aquifer can lead to unintended consequences such as interaquifer leakage or the drying up of springs. Changes in equilibrium conditions can also affect CO2 storage potential http://www.seg.org/SEGportalWEBproject/prod/SEG-News/Images/World/co2methane250px.gif
I. Geothermal: Geothermal exploration and exploitation makes use of groundwater in both fractured and sedimentary rocks to produce electricity. http://www.geodynamics.com.au/IRM/Company/ShowPage.aspx?CPID=1335&PageName=Industry%20Fact%20Sheet