G-FLOWS Stage 3: Hydrogeological conceptual understanding of the Anangu Pitjantjatjara Yankunytjatjara (APY) Lands groundwater system including the Lindsay East Palaeovalley Andrew Love, Adrian Costar, Carmen Krapf, Yueqing Xie, Ilka Wallis, Tessa Lane, Mark Keppel, Kent Inverarity, Zijiuan Deng, Tim Munday and Neville Robinson Goyder Institute for Water Research Technical Report Series No. 20/06 www.goyderinstitute.org Goyder Institute for Water Research Technical Report Series ISSN: 1839-2725 The Goyder Institute for Water Research is a partnership between the South Australian Government through the Department for Environment and Water, CSIRO, Flinders University, the University of Adelaide, and the University of South Australia. The Institute enhances the South Australian Government’s capacity to develop and deliver science-based policy solutions in water management. It brings together the best scientists and researchers across Australia to provide expert and independent scientific advice to inform good government water policy and identify future threats and opportunities to water security. The following Associate organisations contributed to this report: Enquires should be addressed to: Goyder Institute for Water Research Level 4, Rundle Mall Plaza, 50 Rundle Mall, Adelaide, SA 5000 tel: 08 8313 5020 e-mail: [email protected] Citation Love A., Costar A., Krapf C., Xie Y., Wallis I., Lane T., Keppel M., Inverarity K., Deng Z., Munday T. and Robinson N. (2020) G-FLOWS Stage 3: Hydrogeological conceptual understanding of the APY Lands groundwater system including the Lindsay East Palaeovalley. Goyder Institute for Water Research Technical Report Series No. 20/06. Copyright © Crown in right of the State of South Australia, Department for Environment and Water. Disclaimer The Flinders University and Department of Environment and Water, as the project partners, advise that the information contained in this publication comprises general statements based on scientific research and does not warrant or represent the completeness of any information or material in this publication. The project partners do not warrant or make any representation regarding the use, or results of the use, of the information contained herein about to its correctness, accuracy, reliability, currency or otherwise and expressly disclaim all liability or responsibility to any person using the information or advice. Information contained in this document is, to the knowledge of the project partners, correct at the time of writing. Contents Executive summary............................................................................................................................................ vi Acknowledgments ............................................................................................................................................ vii 1 Introduction .......................................................................................................................................... 8 1.1 Background ................................................................................................................................. 8 1.2 Study area ................................................................................................................................... 8 1.3 Previous studies ........................................................................................................................ 11 1.4 Methods, objectives and investigations ................................................................................... 18 2 Regional groundwater conceptualisation ........................................................................................... 24 2.1 Introduction .............................................................................................................................. 24 2.2 Regional geology ....................................................................................................................... 24 2.3 Regional hydrogeology ............................................................................................................. 33 2.4 Regional hydrostratigraphy and architecture ........................................................................... 39 2.5 Groundwater flow systems ....................................................................................................... 44 2.6 Regional tracers and chemistry ................................................................................................ 50 2.7 Groundwater recharge ............................................................................................................. 60 2.8 Numerical slice modelling ......................................................................................................... 63 3 Hydrogeological control site, Lindsay East Palaeovalley ..................................................................... 67 3.1 Geology of the Lindsay East Palaeovalley ................................................................................. 67 3.2 Lindsay East Palaeovalley architecture ..................................................................................... 82 3.3 Hydrochemistry and environmental tracers ............................................................................. 89 3.4 Environmental tracers .............................................................................................................. 94 3.5 Numerical modelling of the Lindsay East Palaeovalley at the hydrogeological control site .. 106 4 Conclusions and recommendations .................................................................................................. 112 GFLOWS Stage 3: Conceptual understanding of the groundwater system at the hydrogeological control site | i Figures Figure 1-1. Regional study area located in the APY Lands. Blue rectangle depicts location of hydrogeological control site where drilling and sampling was conducted for the project. ....................... 10 Figure 1-2. Footprint of groundwater sampling and hydrochemical analysis conducted in the APY Lands (2001, 2012, 2013, and 2014). .................................................................................................................... 12 Figure 1-3. Watertable surface contours (Varma, 2012). .......................................................................... 13 Figure 1-4. Watertable surface contours (Kretschmer and Wohling, 2014). ............................................. 14 Figure 1-5. Recent (2015-17) drilling conducted by DEW for community water supply and road building in APY Lands. .................................................................................................................................................. 16 Figure 1-6. Previous conceptual model for the NW and central parts of the Musgrave Province developed from AEM, TMI and DEM interpretation (Munday et al. 2013): (a) pre-Pliocene landscape (b) contemporary landscape. ........................................................................................................................... 17 Figure 1-7. Footprint of AEM survey conducted in 2016. The pink outline shows the SkyTEM system coverage which covers much of the study area. ........................................................................................ 19 Figure 1-8. Well survey (bore audit) conducted in the initial stages of the project................................... 21 Figure 2-1. Simplified regional structural geology of the Musgrave geological Province, surrounding sedimentary basins and location of palaeovalleys in the far north western regions of South Australia near the Western Australian and Northern Territory borders. Developed after Glorie et al. (2017), and Geoscience Australia. ................................................................................................................................. 25 Figure 2-2. Simplified surface geology across the study area. ................................................................... 27 Figure 2-3. Palaeovalley mapped extent (Krapf et al. 2020) across study area. ........................................ 28 Figure 2-4. Locations of geological cross-section transects across study area. ......................................... 29 Figure 2-5. AEM Conductivity depth section interpretation for the NW-SE transect using AEM (SkyTEM) data (see Fig. 2-4 for transect locations). ................................................................................................... 30 Figure 2-6. AEM Conductivity depth section interpretation for the N-S transect using AEM (SkyTEM) data (see Fig. 2-4 for transect locations). ........................................................................................................... 30 Figure 2-7. Final Interpreted NW-SE transect geological cross-section using existing drillhole information and geophysics. .......................................................................................................................................... 31 Figure 2-8. Final Interpreted N-S transect geological cross-section using existing drillhole information and geophysics. ................................................................................................................................................. 32 Figure 2-9. AEM depth slice 45.3 to 53.8 mBNS draped over TMI data (texture). TMI shows E-W structures. ...................................................................................................................................................................