A multi-tracer approach to constraining artesian groundwater discharge into an alluvial aquifer

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dc.contributor.authorIverach, CPen_AU
dc.contributor.authorCendón, DIen_AU
dc.contributor.authorMeredith, KTen_AU
dc.contributor.authorWilcken, KMen_AU
dc.contributor.authorHankin, SIen_AU
dc.contributor.authorAndersen, MSen_AU
dc.contributor.authorKelly, BFJen_AU
dc.date.accessioned2021-12-02T05:27:14Zen_AU
dc.date.available2021-12-02T05:27:14Zen_AU
dc.date.issued2017-11-28en_AU
dc.date.statistics2021-11-14en_AU
dc.description.abstractUnderstanding pathways of recharge to alluvial aquifers is important for maintaining sustainable access to groundwater resources. Water balance modelling is often used to proportion recharge components and guide sustainable groundwater allocations. However, it is not common practice to use hydrochemical evidence to inform and constrain these models. Here we compare geochemical versus water balance model estimates of artesian discharge into an alluvial aquifer, and demonstrate why multi-tracer geochemical analyses should be used as a critical component of water budget assessments. We selected a site in Australia where the Great Artesian Basin (GAB), the largest artesian basin in the world, discharges into the Lower Namoi Alluvium (LNA), an extensively modelled aquifer, to convey the utility of our approach. Water stable isotopes (δ18O and δ2H) and the concentrations of Na+ and HCO3− suggest a continuum of mixing in the alluvial aquifer between the GAB (artesian component) and surface recharge, whilst isotopic tracers (3H, 14C, and 36Cl) indicate that the alluvial groundwater is a mixture of groundwaters with residence times of < 70 years and groundwater that is potentially hundreds of thousands of years old, which is consistent with that of the GAB. In addition, Cl− concentrations provide a means to calculate a percentage estimate of the artesian contribution to the alluvial groundwater. In some locations, an artesian contribution of up to 70 % is evident from the geochemical analyses, a finding that contrasts with previous regional-scale water balance modelling estimates that attributed 22 % of all inflow for the corresponding zone within the LNA to GAB discharge. Our results show that hydrochemical investigations need to be undertaken as part of developing the conceptual framework of a catchment water balance model, as they can improve our understanding of recharge pathways and better constrain artesian discharge to an alluvial aquifer. © Author(s) 2017. This work is distributed under the Creative Commons Attribution 4.0 Licence.en_AU
dc.description.sponsorshipThis research was funded by the Cotton Research and Development Corporation (CRDC). Charlotte Iverach was supported by scholarships from the Australian Government, ANSTO, and CRDC.en_AU
dc.identifier.citationIverach, C. P., Cendón, D. I., Meredith, K. T., Wilcken, K. M., Hankin, S. I., Andersen, M. S., & Kelly, B. F. J. (2017). A multi-tracer approach to constraining artesian groundwater discharge into an alluvial aquifer. Hydrology and Earth System Sciences 21(11), 5953–5969. doi:10.5194/hess-21-5953-2017, 2017.en_AU
dc.identifier.issn1607-7938en_AU
dc.identifier.issue11en_AU
dc.identifier.journaltitleHydrology and Earth System Sciencesen_AU
dc.identifier.pagination5953-5969en_AU
dc.identifier.urihttps://doi.org/10.5194/hess-21-5953-2017en_AU
dc.identifier.urihttps://apo.ansto.gov.au/dspace/handle/10238/12322en_AU
dc.identifier.volume21en_AU
dc.language.isoenen_AU
dc.publisherEuropean Geosciences Unionen_AU
dc.subjectTracer techniquesen_AU
dc.subjectGround wateren_AU
dc.subjectAquifersen_AU
dc.subjectArtesian basinsen_AU
dc.subjectGeochemistryen_AU
dc.subjectWateren_AU
dc.subjectAustraliaen_AU
dc.subjectStable isotopesen_AU
dc.subjectSimulationen_AU
dc.subjectWatershedsen_AU
dc.titleA multi-tracer approach to constraining artesian groundwater discharge into an alluvial aquiferen_AU
dc.typeJournal Articleen_AU
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