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dc.contributor.authorCartwright, Ianen_US
dc.contributor.authorWerner, Adrian Den_US
dc.contributor.authorWoods, Juliette Aen_US
dc.date.accessioned2019-06-27T05:02:08Z
dc.date.available2019-06-27T05:02:08Z
dc.date.issued2019-01-24
dc.identifier.citationCartwright, I., Werner, A. D., & Woods, J. A. (2019). Using geochemistry to discern the patterns and timescales of groundwater recharge and mixing on floodplains in semi-arid regions. Journal of Hydrology, 570, 612–622. https://doi.org/10.1016/j.jhydrol.2019.01.023en_US
dc.identifier.issn0022-1694
dc.identifier.urihttp://hdl.handle.net/2328/39246
dc.description© 2019 Elsevier Ltd. This manuscript version is made available under the CC-BY-NC-ND 4.0 license: http://creativecommons.org/licenses/by-nc-nd/4.0/ This author accepted manuscript is made available following 24 month embargo from date of publication (January 2019) in accordance with the publisher’s archiving policyen_US
dc.description.abstractFloodplains may alternate between discharge zones for regional groundwater and areas of recharge from river water during high-flow events. Understanding the mechanisms and timescales of recharge on floodplains is important for their management and for the protection of fragile ecosystems. The floodplains of the River Murray host important ecosystems, particularly remnant eucalypt forests that are vulnerable to changes in inundation, rising regional water tables, and salt accumulation. This study addresses floodplain recharge and groundwater mixing on the Pike and Katarapko floodplains of South Australia. At Pike, 3H activities of groundwater in the low hydraulic conductivity Coonambidgal Formation that crops out on the floodplain are ∼0.25 TU. 3H activities of groundwater in the underlying higher hydraulic conductivity Monoman Formation decrease from ∼1 TU near the contact with the Coonambidgal Formation to <0.02 TU at >15 m depth. Groundwater 14C activities are between 40 and 95 pMC but are less well correlated with depth. The 3H or 14C activities do not vary systematically with distance from the surface water channels on the floodplains. These observations imply that groundwater recharge at Pike is dominantly through the floodplain rather than through the channel banks. In contrast to the regional groundwater where total dissolved solids (TDS) concentrations are commonly >35,000 mg/L, the TDS of groundwater on the floodplain is locally <500 mg/L. A correlation between 3H activities and TDS and the presence of groundwater with relatively low 14C activities but above detection 3H activities implies that recently recharged waters have mixed with regional groundwater in the floodplain sediments. The 3H activities in these mixed waters implies that mixing occurs over a few years. By contrast, at Katarapko, the highest 3H activities in the Monoman Formation groundwater (up to 2.35 TU) are closer to the Murray River, implying that recharge through the bank may occur. These contrasting patterns of recharge probably reflect local topographic controls. Understanding the recharge-discharge relationships are vital for managing proposed floodplain inundation programs aimed at improving ecosystem health.en_US
dc.language.isoenen_US
dc.publisherElsevieren_US
dc.relationhttp://purl.org/au-research/grants/arc/LP140100317en_US
dc.relationhttp://purl.org/au-research/grants/arc/FT150100403en_US
dc.rights© 2019 Elsevier Ltd.en_US
dc.subjectTritiumen_US
dc.subjectcarbon-14en_US
dc.subjectMurray Riveren_US
dc.subjectfloodplain rechargeen_US
dc.subjectPike floodplainen_US
dc.subjectsurficial clay unit.en_US
dc.subjectKatarapko floodplainen_US
dc.subjectriverbank rechargeen_US
dc.subjecthealth of floodplain ecosystemsen_US
dc.titleUsing geochemistry to discern the patterns and timescales of groundwater recharge and mixing on floodplains in semi-arid regionsen_US
dc.typeArticleen_US
dc.relation.grantnumberARC/LP140100317en_US
dc.relation.grantnumberARC/FT150100403en_US
dc.identifier.doihttps://doi.org/10.1016/j.jhydrol.2019.01.023en_US
dc.rights.holderElsevier Ltd.en_US
dc.rights.licenseCC-BY-NC-ND
local.contributor.authorOrcidLookupCartwright, Ian: https://orcid.org/0000-0001-5300-4716en_US
local.contributor.authorOrcidLookupWerner, Adrian D: https://orcid.org/0000-0002-1190-1301en_US
local.contributor.authorOrcidLookupWoods, Juliette A: https://orcid.org/0000-0002-3669-5049en_US


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