Using 14C and 3H to understand groundwater flow and recharge in an aquifer window

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dc.contributor.authorAtkinson, APen_AU
dc.contributor.authorCartwright, Ien_AU
dc.contributor.authorGilfedder, BSen_AU
dc.contributor.authorCendón, DIen_AU
dc.contributor.authorUnland, NPen_AU
dc.contributor.authorHofmann, Hen_AU
dc.date.accessioned2015-12-28T04:10:47Zen_AU
dc.date.available2015-12-28T04:10:47Zen_AU
dc.date.issued2014-12-09en_AU
dc.date.statistics2015-12-28en_AU
dc.description.abstractKnowledge of groundwater residence times and recharge locations is vital to the sustainable management of groundwater resources. Here we investigate groundwater residence times and patterns of recharge in the Gellibrand Valley, southeast Australia, where outcropping aquifer sediments of the Eastern View Formation form an "aquifer window" that may receive diffuse recharge from rainfall and recharge from the Gellibrand River. To determine recharge patterns and groundwater flow paths, environmental isotopes (3H, 14C, δ13C, δ18O, δ2H) are used in conjunction with groundwater geochemistry and continuous monitoring of groundwater elevation and electrical conductivity. The water table fluctuates by 0.9 to 3.7 m annually, implying recharge rates of 90 and 372 mm yr−1. However, residence times of shallow (11 to 29 m) groundwater determined by 14C are between 100 and 10 000 years, 3H activities are negligible in most of the groundwater, and groundwater electrical conductivity remains constant over the period of study. Deeper groundwater with older 14C ages has lower δ18O values than younger, shallower groundwater, which is consistent with it being derived from greater altitudes. The combined geochemistry data indicate that local recharge from precipitation within the valley occurs through the aquifer window, however much of the groundwater in the Gellibrand Valley predominantly originates from the regional recharge zone, the Barongarook High. The Gellibrand Valley is a regional discharge zone with upward head gradients that limits local recharge to the upper 10 m of the aquifer. Additionally, the groundwater head gradients adjacent to the Gellibrand River are generally upwards, implying that it does not recharge the surrounding groundwater and has limited bank storage. 14C ages and Cl concentrations are well correlated and Cl concentrations may be used to provide a first-order estimate of groundwater residence times. Progressively lower chloride concentrations from 10 000 years BP to the present day are interpreted to indicate an increase in recharge rates on the Barongarook High. © Author(s) 2014.en_AU
dc.identifier.citationAtkinson, A. P., Cartrwight, I., Gilfedder, B. S., Cendón, D. I., Unland, N. P., & Hofmann, H. (2014). Using 14C and 3H to understand groundwater flow and recharge in an aquifer window. Hydrology and Earth System Sciences, 18(12), 4951–4964. doi:10.5194/hess-18-4951-2014en_AU
dc.identifier.govdoc6362en_AU
dc.identifier.issn1607-7938en_AU
dc.identifier.issue12en_AU
dc.identifier.journaltitleHydrology and Earth System Sciencesen_AU
dc.identifier.pagination4951-4964en_AU
dc.identifier.urihttps://doi.org/10.5194/hess-18-4951-2014en_AU
dc.identifier.urihttp://apo.ansto.gov.au/dspace/handle/10238/6503en_AU
dc.identifier.volume18en_AU
dc.language.isoenen_AU
dc.publisherCopernicus Publicationsen_AU
dc.subjectGround wateren_AU
dc.subjectAustraliaen_AU
dc.subjectAquifersen_AU
dc.subjectEnvironmenten_AU
dc.subjectRiversen_AU
dc.subjectChloridesen_AU
dc.titleUsing 14C and 3H to understand groundwater flow and recharge in an aquifer windowen_AU
dc.typeJournal Articleen_AU
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