Hydrochemical assessment of a freshwater resource on Rottnest Island, Western Australia

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dc.contributor.authorWells, Een_AU
dc.contributor.authorMeredith, KTen_AU
dc.contributor.authorBaker, AAen_AU
dc.contributor.authorPost, VEAen_AU
dc.contributor.authorAndersen, MSen_AU
dc.date.accessioned2016-04-04T06:40:49Zen_AU
dc.date.available2016-04-04T06:40:49Zen_AU
dc.date.issued2015-11-03en_AU
dc.date.statistics2016-03-04en_AU
dc.description.abstractThis project investigated the groundwater hydrochemical processes within an Island aquifer system on Rottnest Island, located ~18 km west of Perth, WA. A freshwater lens on the Island supplies around 25% of the Island’s potable water requirements, however there is limited information regarding the dynamics of the lens and its resilience to ongoing abstraction and reduced recharge. Understanding the hydrochemical processes and residence times of the groundwater is essential for making use of the system sustainable. Groundwater samples were collected quarterly from 12 production bores to obtain seasonal information and from 15 monitoring bores biannually to monitor the mixing zone. Rainfall samples were collected on a weekly basis. The chemical composition of water samples were analysed by ion chromatography and inductively coupled plasma-mass spectrometry, while and stable water isotopes (SWIs) were analysed by isotope ratio mass spectrometry. Tritium was analysed by liquid scintillation after being distilled and electrolytically enriched. hydrochemical analysis shows varied water types and suggests a mixing trend between a fresh and saline end-member. Samples range in composition from fresh Ca-Na-Mg-3-Cl to saline Na-Cl groundwaters with increasing electrical conductivity (EC). The mixing trend is also observed in the SWIs results, with the values becoming more enriched with increasing EC. Fresh water within the lens was found to be ‘young’ and recharged within the last 10 to 30 years. While the fresh groundwater beneath Rottnest Island was found to be recently recharged and is arguably a sustainable resource, the hydrochemical results highlight the importance of a long-term management strategy to ensure that the mixing zone below thefreshwater lens does not increase to a point where the freshwater source is no longer viable. The declining winter rainfall in the Perth region, resulting in reduced recharge to the lens, makes the management of this resource even more essential. ©The Authors.en_AU
dc.identifier.citationWells, E., Meredith, K., Baker, A., Post, P., & Andersen, M. (2015). Hydrochemical assessment of a freshwater resource on Rottnest Island, Western Australia. Paper presented at the Australian Groundwater Conference, 3-5 November 2015, The Shine Dome, Canberra, Australia, (pp. 101). Retrieved from: https://www.iah.org.au/wp-content/uploads/2019/09/AGC2015-Book-of-Abstracts.pdfen_AU
dc.identifier.conferenceenddate5 November 2015en_AU
dc.identifier.conferencenameAustralian Ground Water Conference, 2015en_AU
dc.identifier.conferenceplaceThe Shien Dome, Canberra, Australia.en_AU
dc.identifier.conferencestartdate3 November 2015en_AU
dc.identifier.govdoc6415en_AU
dc.identifier.urihttps://www.iah.org.au/wp-content/uploads/2019/09/AGC2015-Book-of-Abstracts.pdfen_AU
dc.identifier.urihttp://apo.ansto.gov.au/dspace/handle/10238/6677en_AU
dc.language.isoenen_AU
dc.publisherNational Centre for Groundwater Research and Trainingen_AU
dc.subjectWestern Australiaen_AU
dc.subjectFresh wateren_AU
dc.subjectGround wateren_AU
dc.subjectAquifersen_AU
dc.subjectTritiumen_AU
dc.subjectRainen_AU
dc.titleHydrochemical assessment of a freshwater resource on Rottnest Island, Western Australiaen_AU
dc.typeConference Presentationen_AU
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