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Three-Dimensional Seawater Intrusion Modelling of Uley South Basin, South Australia

  • Adrian D. Werner
  • Le Dung Dang
Chapter
Part of the Coastal Research Library book series (COASTALRL, volume 7)

Abstract

Groundwater in the Uley South basin is a vital source of water supply in the Eyre Peninsula, providing approximately 70 % of the region’s reticulated water. The groundwater resources are at risk of seawater intrusion given that the aquifer is in direct contact with the sea, and that a general lowering of hydraulic heads has occurred over the past two decades. Seawater intrusion has not been investigated thoroughly in Uley South basin; a similar situation for many of Australia’s coastal aquifers. This study develops a three-dimensional seawater intrusion model of Uley South basin using the code MODHMS. The modelling simulates for the first time the current extent of seawater in the aquifer, the temporal salinity variability, and the susceptibility of the aquifer to seawater intrusion, and as such, the model is a significant step forward beyond previous modelling attempts, providing important insights into salinity distributions and salinity mobility. While it is limited by the available information at the time, comparisons with alternative attempts at salinity measurements (e.g. an AEM survey) show a relatively close match between simulated and observed salinities; an encouraging result given well-documented uncertainties in seawater intrusion modelling. Simulations explore the effects of alternative pumping regimes, reduced recharge, and seasonality and other temporal variability effects on seawater intrusion that cannot be assessed using other methods. The impacts of pumping and recharge changes under climate variability are distinguished; both forms of aquifer stress potentially impact on heads and salinities to somewhat similar extents. The ability of the system to recover from long-term pumping is also assessed. At the basin scale, historical changes in the position of the freshwater-seawater interface are mostly localised due to the shape of the aquifer near the coastline (i.e. basement sloping towards the sea). However, the model predicts that some near-coastal piezometers may show increasing salinity trends in the future if current pumping practices continue, and in particular if recharge diminishes under climate change. A comparison between highly dynamic and averaged-stress conditions demonstrates that seasonality is a minor controlling factor in seawater intrusion trends. Aquifer recovery times exceed the periods during which the pumping stresses that induce seawater intrusion are applied. This occurs because cycles of pumping and recovery widen the transition zone between freshwater and seawater, and a large mass of salt remains in the aquifer even after an extensive recovery period.

Keywords

Seawater Intrusion Salinity Distribution Observe Water Level Salinity Trend Eyre Peninsula 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Notes

Acknowledgments

This research was funded by Flinders University, the South Australian Government, and the National Centre for Groundwater Research and Training (a collaborative initiative of the Australian Research Council and the National Water Commission). The authors wish to acknowledge the invaluable input of industry partners and Flinders University students and staff for their contributions to this research.

References

  1. Berrio JF (2010) A numerical 3D seawater intrusion model of Uley South Basin, Eyre Peninsula, South Australia. Unpublished master’s thesis, Flinders University, Adelaide, 52 ppGoogle Scholar
  2. Doherty J (2005) PEST: model-independent parameter estimation, user manual, 5th edn. Watermark Numerical Computing. Brisbane. Available at: http://www.pesthomepage.org/Download.php, 336 pp
  3. Evans SL (1997) Estimating long-term recharge to thin, unconfined carbonate aquifers using conventional and environmental isotope techniques: Eyre Peninsula, South Australia. Incomplete master’s thesis, Flinders University, Adelaide, 176 ppGoogle Scholar
  4. Fitzpatrick A, Cahill K, Munday T (2009) Informing the hydrogeology of Coffin Bay, South Australia, through the constrained inversion of TEMPEST AEM Data. CSIRO, Adelaide, 159 ppGoogle Scholar
  5. Freeze RA, Cherry JA (1979) Groundwater. Prentice-Hall, Englewood CliffsGoogle Scholar
  6. Harbaugh AW, McDonald MG (1996) User’s documentation for MODFLOW-96, an update to the U.S. Geological Survey modular finite-different ground-water flow model. U.S. Geological Survey Open-File Report 96-485. U.S. Geological Survey, Reston, 63 ppGoogle Scholar
  7. Harrington N, Evans S, Zulfic D (2006) Uley Basin groundwater modelling project. Project overview and conceptual model development, vol 1. Report DWLBC 2006/01. Department of Water, Land and Biodiversity Conservation, AdelaideGoogle Scholar
  8. Hutson JL, Wagenet RJ, Niederhofer ME (1997) LEACHM: Leaching estimation and chemistry model – a process-based model of water and solute movement, transformations, plant uptake and chemistry reactions in the unsaturated zone. Department of Soil, Crop and Atmospheric Sciences, Research Series No. R97-1, Cornell University, Ithaca, 138 ppGoogle Scholar
  9. HydroGeoLogic, Inc (2006) MODHMS: a comprehensive MODFLOW-based hydrologic modeling system, Version 3.0. HydroGeoLogic, Inc, Herndon, 811 ppGoogle Scholar
  10. Li C (2008) Water use by Malle-form Eucalyptus diversifolia in a semi-arid and karstic environment. Unpublished honours thesis, Flinders University, Adelaide, 65 ppGoogle Scholar
  11. Liu F, Anh W, Turner I, Bajracharya K, Huxley WJ, Su N (2006) A finite volume simulation model for saturated-unsaturated flow and application to Gooburrum, Bundaberg, Queensland, Australia. Appl Math Model 30:352–366CrossRefGoogle Scholar
  12. Morton WH, Steel TM (1968) Eyre Peninsula groundwater study Uley South Basin, Progress report No. 1 – Aquifer Evaluation. Department of Mines, Report 66/45, Government of South Australia, AdelaideGoogle Scholar
  13. Narayan KA, Schleeberger C, Bristow KL (2007) Modelling seawater intrusion in the Burdekin Delta Irrigation Area, North Queensland, Australia. Agric Water Manage 89:217–228CrossRefGoogle Scholar
  14. Ordens CM, Werner AD, Post VEA, Hutson JL, Simmons CT, Irvine BM (2012) Groundwater recharge to a sedimentary aquifer in the topographically closed Uley South Basin, South Australia. Hydrogeol J 20:61–72CrossRefGoogle Scholar
  15. Seidel A (2008) Seawater intrusion on the Southern Eyre Peninsula, South Australia: a first-order assessment. Unpublished honours thesis, Flinders University, Adelaide, 69 ppGoogle Scholar
  16. Ward JD, Hutson J, Howe B, Fildes S, Werner AD, Ewenz C (2009), A modelling framework for the assessment of recharge processes and climate change: Eyre Peninsula. Report developed through the Eyre Peninsula Groundwater, Allocation and Planning Project, Eyre Peninsula Natural Resources Management Board, 53 pp. http://www.epnrm.sa.gov.au/Portals/4/Water/Recharge%20and%20Climate%20Change%20Final%20Report.pdf
  17. Ward JD, Werner AD, Howe B (2009) Saltwater intrusion in Southern Eyre Peninsula. Report developed through the Eyre Peninsula Groundwater, Allocation and Planning Project, Government of South Australia, Eyre Peninsula Natural Resources Management Board, Eyre Peninsula, 56 ppGoogle Scholar
  18. Watson TA, Werner AD, Simmons CT (2010) Transience of seawater intrusion in response to sea level rise. Water Resour Res 46:W12533. doi: 10.1029/2010WR009564 CrossRefGoogle Scholar
  19. Werner AD (2010a) A groundwater flow model of Uley South Basin, South Australia. Draft report prepared for the Eyre Peninsula Natural Resource Management Board by Flinders University, Adelaide, 105 ppGoogle Scholar
  20. Werner AD (2010b) A review of seawater intrusion and its management in Australia. Hydrogeol J 18:281–285CrossRefGoogle Scholar
  21. Werner AD, Gallagher MR (2006) Characterisation of sea-water intrusion in the Pioneer Valley, Australia using hydrochemistry and three-dimensional numerical modelling. Hydrogeol J 14:1452–1469CrossRefGoogle Scholar
  22. Werner AD, Alcoe DW, Ordens CM, Hutson JL, Ward JD, Simmons CT (2011) Current practice and future challenges in coastal aquifer management: flux-based and trigger-level approaches with application to an Australian case study. Water Resour Manage 25:1831–1853CrossRefGoogle Scholar
  23. Zulfic D, Harrington N, Evans S (2007) Uley basin groundwater modelling project. Groundwater flow model, vol 2. Department of Water, Land and Biodiversity Conservation, Report DWLBC 2007/04, Government of South Australia, Adelaide, 128 ppGoogle Scholar

Copyright information

© Springer Science+Business Media Dordrecht 2013

Authors and Affiliations

  1. 1.National Centre for Groundwater and Research and TrainingFlinders UniversityAdelaideAustralia
  2. 2.School of the EnvironmentFlinders UniversityAdelaideAustralia

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