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  • Water resource assessment for the Great Artesian Basin. Synthesis of a report to the Australian Government from the CSIRO Great Artesian Basin Water Resource Assessment

  • This data set comprises one of three archives of Geoscience Australia work in the project "A Consistent Approach to Groundwater Recharge Determination in Data Poor Areas". The project was carried out by CSIRO and Geoscience Australia and was funded by the National Water Commission Raising National Water Standards program. The data contained included Original data sourced for the project, Final data produced by the project, MXD's of maps created, and tools used within the project. The archives created for this project comprise: 1. Data archive. Data set stored in the GA CDS. Geocat Record number 79804 2. Adminstration and publication archive. Documents stored in TRIM Project P10/67 RECHARGE-DISCHARGE PROJECT 3. References archive. Endnote library located at \\nas\eg\water\References\Recharge_Discharge_Project.enl For more information about the creation of these archives, including the location of files, see TRIM D2014-102808 For more information about the project, see the following references: Leaney F, Crosbie R, O'Grady A, Jolly I, Gow L, Davies P, Wilford J and Kilgour P. 2011. Recharge and discharge estimation in data poor areas: Scientific reference guide. CSIRO: Water for a Healthy Country National Research Flagship. 61 pp (GA Record No. 2011/46 GACat # 71941) Jolly I, Gow L, Davies P, O'Grady A, Leaney F, Crosbie R, Wilford J and Kilgour P. 2011. Recharge and discharge estimation in data poor areas: User guide for the recharge and discharge estimation spreadsheets and MapConnect. CSIRO: Water for a Healthy Country National Research Flagship. 40 pp. (GA Record No. 2011/35 GeoCat # 71940) Pain, C.F., Gow, L.J, Wilford, J.R. and Kilgour, P. 2011. Mapping approaches to recharge and discharge estimation and associated input datasets. A report for CSIRO: Water for a Healthy Country National Research Flagship. (Professional Opinion No. 2011/01 GeoCat # 70392)

  • This report describes the findings of the Great Artesian Basin Water Resource Assessment that have led to advancing the understanding of the GAB. It encapsulates findings that are presented in four region reports and a technical report on conceptualising the GAB that were prepared for the Assessment. Advancing the conceptual understanding of the GAB requires careful evaluation of the geological framework (i.e. the layers of rock), description of how the geology translates into hydrostratigraphy (i.e. the relative ability of specific layers to store and transmit water) and investigation of the groundwater conditions (i.e. watertable, groundwater levels, and inferred movement). It is the geological framework, hydrostratigraphy and groundwater conditions that are the basis for conceptualising water resources in the GAB. The conceptual understanding of the GAB provides the foundation for assessing water availability and providing guidance to water policy and water resource planning.

  • Fresh groundwater resources are a highly valuable commodity, particularly in semi-arid to arid landscapes where annual precipitation is low and surface water is scarce. Water security, often achieved through the development of groundwater resources, is a high priority for rural communities within these water-limited landscapes. However this is often at the expense of the environment when alterations to the groundwater system, often in conjunction with drought conditions, can detrimentally impact floodplain and riparian vegetation structure and function. Remote-sensing methods can be used to detect such changes in vegetation. In this study, a multi-temporal Landsat Normalised Difference Vegetation Index (NDVI) approach was used to detect changes in riparian and floodplain vegetation in the Lower-Darling floodplain, NSW, Australia. When integrated with surface and subsurface data, these changes provided insight into how surface water availability and subsurface geological and hydrogeological characteristics influenced vegetation distribution and behaviour at multiple scales. It was found that while the availability of water resources was the primary driver of changes in vegetation canopy dynamics, this availability was strongly influenced by both tectonic and hydrogeological processes. These findings were of particular importance when considering the suitability of groundwater development options and they have implications for future groundwater assessment studies.

  • Poster prepared for International Association of Hydrogeologists Congress 2013 The Broken Hill Managed Aquifer Recharge (BHMAR) project has successfully mapped a multi-layered sequence of aquitards and aquifers, as well potential groundwater resource and managed aquifer recharge (MAR) targets, in the top 100m of the Darling Floodplain. Near-surface aquitards overlying the Pliocene target aquifers (fluvial Calivil Formation (CFm) and marine Loxton-Parilla Sands (LPS)), were identified initially as variably conductive layers in airborne electromagnetic (AEM) data, and validated by drilling and complementary borehole geophysical, textural, hydrogeological and hydrochemical studies. The stratigraphic unit underlying the Pliocene aquifers is the Miocene upper Renmark Group (uRG). Drilling and AEM data have confirmed this unit is present throughout the study area, deposited predominantly as thick muds. Facies and biofacies analysis suggests these muds were deposited on a low relief sedimentary plain with a high water table and numerous permanent water bodies, with relatively minor sand bodies deposited in narrow anastomosing fixed channel streams. Groundwater in the upper uRG is saline, and muddy sediments form a strongly conductive layer beneath the Pliocene aquifers. This is a much harder geophysical target than the upper confining aquitards, as the target lies at depths of 80-120m, which is near the depth resolution of the AEM system. Furthermore, there is little conductivity contrast between the Pliocene and uRG sediments except in areas where there is fresh groundwater in the former. Hydrochemical and hydrodynamic data shows that there is limited hydrological connection between the uRG and less saline Pliocene aquifers, except where the Pliocene is underlain by uRG channel sands. These channels are much narrower (10s to ~100m) and thinner (1 to 10m) compared with palaeochannels in the overlying CFm. Where the channels are connected, there can be a distinct salinity gradient from the Pliocene into the uRG sands, indicating localised mixing. Given the potential for up-coning of saline groundwater in these instances, a number of sites (e.g. Menindee Common), have been assessed as unsuitable for MAR. Overall, the uRG muds act as a good lower confining aquitard to the Pliocene aquifers over most of the project area, including a number of potential MAR and groundwater resource targets.

  • The Habanero Enhanced Geothermal System (EGS) in central Australia has been under development since 2002, with several deep (more than 4000 m) wells drilled to date into the high-heat-producing granites of the Big Lake Suite. Multiple hydraulic stimulations have been performed to improve the existing fracture permeability in the granite. Stimulation of the newly-drilled Habanero-4 well (H-4) was completed in late 2012, and micro-seismic data indicated an increase in total stimulated reservoir area to approximately 4 km². Two well doublets have been tested, initially between Habanero-1 (H-1) and Habanero-3 (H-3), and more recently, between H-1 and H-4. Both doublets effectively operated as closed systems, and excluding short-term flow tests, all production fluids were re-injected into the reservoir at depth. Two inter-well tracer tests have been conducted: the first in 2008, and the most recent one in June 2013, which involved injecting 100 kg of 2,6 naphthalene-disulfonate (NDS) into H-1 to evaluate the hydraulic characteristics of the newly-created H-1/H-4 doublet. After correcting for flow hiatuses and non-steady-state flow conditions, tracer breakthrough in H-4 was observed after 6 days (compared to ~4 days for the previous H-1/H-3 doublet), with peak breakthrough occurring after 17 days. Extrapolation of the breakthrough curve to late time indicates that approximately 60% of the tracer mass would eventually be recovered (vs. approximately 80% for the 2008 H-1/H-3 tracer test). This suggests that a large proportion of the tracer may lie trapped in the opposite end of the reservoir from H-4 and/or may have been lost to the far field. The calculated inter-well swept pore volume is approximately 31,000 m³, which is larger than that calculated for the H-1/H-3 doublet (~20,000 m³). A simple 2D TOUGH2 tracer model, with model geometry constructed based on the current conceptual understanding of the Habanero EGS system, demonstrates good agreement with the measured tracer returns in terms of timing of breakthrough in H-4, and observed tracer dispersion in the tail of the breakthrough curve.

  • Poster prepared for International Association of Hydrogeologists Congress 2013 Sonic drilling is a relatively new technology that was used successfully to obtain relatively uncontaminated and undisturbed continuous core samples with excellent (>99%) recovery rates to depths of 206m in unconsolidated fluvio-lacustrine sediments of the Darling River floodplain. However, there are limitations with the standard sonic coring method. Sands, in particular, are disturbed when they are vibrated out of the core barrel into the flexible plastic sampling tube. There can be changes to moisture content, pore fluid chemistry and sediment mineralogy on exposure to the atmosphere, even when the samples are processed and analysed soon after collection. The option exists during sonic drilling to encapsulate the core in rigid polycarbonate lexan tubes. Although this increases costs and reduces drilling rates, atmospheric exposure of the core during drilling is reduced to the ends of the lexan tubes before being capped. In addition, the tubes can be purged with an inert gas such as argon. Lexan coring is best carried out below the watertable as the heat from drilling dry clays can cause the polycarbonate to melt. In the study, 60 sonic holes (4.5 km) and 40 rotary mud holes (2 km) were obtained as part of a program to map and assess potential groundwater resources and managed aquifer recharge (MAR) targets over a large area (7,500 km2) of the Darling River floodplain. Two of the sonic bores were drilled to depths of 60 metres to obtain lexan-encapsulated core samples. These cores were used to obtain less perturbed samples for pore fluid analysis (salinity, major ions, trace metals, stable isotopes), textural analysis, and analysis of mineral phases to help assess aquifer clogging potential (using XRD, XRF, SEM). An additional advantage of the lexan coring was the recovery of encapsulated and intact sediment intervals for determining porosities, effective porosities, hydraulic conductivities, and other geophysical and petrophysical measurements. By painting some tubes black, sand samples were also successfully obtained for optically stimulated luminescence (OSL) dating. Alternatively, opaque black lexan can be made to order by the supplier. Overall, the superior sample integrity obtained from lexan coring enables a greater range of hydrogeological and hydrochemical parameters to be assessed.

  • This project aims to characterise the hydrogeochemistry of groundwater associated with coal seams and surrounding aquifers in the Surat Region and Laura Basin. In addition, the project provides an assessment of the environmental values of groundwater in relation to ecological and human use, and general guidance on groundwater quality monitoring strategies. . Full details of the methodology and findings of the study, including limitations and assumptions are provided in this project technical report.

  • Freshwater coastal aquifers provide an important resource for irrigated agriculture, human consumption and the natural environment. Approximately 18 million people live within 50 km of the coast in Australia, and many coastal communities are reliant on groundwater. These coastal aquifers are vulnerable to seawater intrusion (SWI) - the landward encroachment of seawater - due to their close proximity to the ocean. To assess the threat of SWI in Australia, a comprehensive literature review was undertaken with input from state/territory agencies. The literature review, in combination with contributions from stakeholders, identified sites within each of the states and the Northern Territory where SWI had been reported or where it was considered to be a serious threat. International Association of Hydrogeologists 2013 Congress poster

  • Poster prepared for International Association of Hydrogeologists Congress 2013 In this study, a multi-disciplinary systems mapping approach has completely revised our understanding of the age, stratigraphy, mode of deposition and landscape evolution of Lower Darling Valley (LDV) sediments within the north-western Murray Basin. The Cenozoic sequence in this area contains Paleogene and Neogene shallow marine, fluvial and shoreline sediments overlain by Quaternary lacustrine, aeolian and fluvial units. The surficial Quaternary fluvial units of the valley form a complex group of morphostratigraphic units which vary in their distribution, character and geomorphic expression through the study area. Resolving the distribution of these units has been particularly important for understanding surface-groundwater interactions. In the LDV Quaternary fluvial sequence, multiple scroll-plain tracts are incised into higher, older more featureless floodplains. Prior to this study, these were respectively correlated to the Coonambidgal and Shepparton Formations of the Riverine Plain in the eastern Murray Basin and associated with the subsequently discarded Prior Stream/Ancestral River chronosequence of different climatically controlled depositional styles. In contrast to that proposition, we ascribe all LDV Quaternary fluvial deposition to lateral-migration depositional phases of one style, though with more variable stream discharges and channel and meander-scroll dimensions. Successively higher overbank-mud deposition through time obscures scroll traces and provides the main ongoing morphologic difference. A new morphostratigraphic unit, the Menindee Formation, refers to the mostly older and higher floodplain sediments, where scroll traces are obscured by overbank mud which continues to be deposited by the highest modern floods. Younger inset scroll-plain tracts, with visible scroll-plain traces, are still referred to the Coonambidgal Formation. Another new stratigraphic unit, the Willotia beds, refers to even older fluvial sediments, now above modern floodplain levels and mostly covered by aeolian sediments. This work provides important insights into the nature of Australian Quaternary fluvial deposition, with important implications for hydrogeological processes, groundwater resources and the assessment of managed aquifer recharge options.