The canary or the coalmine? Isotopic evidence of drying climate versus groundwater outflow as the cause for recent losses from Thirlmere Lakes, NSW

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dc.contributor.authorPeterson, MAen_AU
dc.contributor.authorCendón, DIen_AU
dc.contributor.authorHughes, CEen_AU
dc.contributor.authorCrawford, Jen_AU
dc.contributor.authorHankin, SIen_AU
dc.contributor.authorKrogh, Men_AU
dc.contributor.authorCowley, KLen_AU
dc.contributor.authorCohen, TJen_AU
dc.contributor.authorAndersen, MSen_AU
dc.contributor.authorAnibas, Cen_AU
dc.contributor.authorGlamore, Wen_AU
dc.contributor.authorChen, SYen_AU
dc.contributor.authorTimms, Wen_AU
dc.contributor.authorMcMillan, Ten_AU
dc.date.accessioned2021-08-30T07:28:19Zen_AU
dc.date.available2021-08-30T07:28:19Zen_AU
dc.date.issued2019-11-24en_AU
dc.date.statistics2021-08-16en_AU
dc.description.abstractThe Thirlmere Lakes Research Program (TLRP) is a collaboration investigating water loss mechanisms in recent drying of five adjacent lakes, located 75 km south-west of Sydney. Some stakeholders and previous studies have perceived a correlation with local longwall coal mining history and suspect deep fracture outflow. Others suggest the lakes are simply responding to a drier climate, serving as the canary in the broader climate-change ‘coal mine’. ANSTO has applied recurrent isotopic and chemical monitoring of the lakes and adjacent groundwater over two years to unravel some of the mystery of their recent water losses. Each lake behaved uniquely, but they shared some common trends. Steady enrichment of stable water isotopes, 2H and 18O, indicates the dominance of evaporation, with minimal losses to groundwater or through transpiration. Lake Cl/Br ratios were very low and clustered in three groups, two trending away from initial ratios indicative of groundwater input. 3H and 14C show recent rainfall and/or runoff as the main contributors to lake waters, with apparent ages in the adjacent shallow groundwater up to several decades. High levels of 222Rn from shallow bores suggest a close association between the peats enclosing the lakes and 238 U from ancient erosion, or proximity of an underlying shale lens. The only deep piezometer (72-84 m) near the lakes showed negligible contributions from the lakes or recent surface water. The trends in isotopic and chemical parameters infer that evaporation is sufficient to explain recent water losses from most of these perched lakes. Trends in some lakes hint that these had previous inputs from groundwater. While the historical variability of groundwater input to the lakes remains unknown, there is no current evidence of major losses to groundwater. Thirlmere Lakes will exist only intermittently under dry climate conditions. © The Authorsen_AU
dc.identifier.citationPeterson, M. A., Cendón, D. Hughes, C., Crawford, J., Hankin, S., Krogh, M., Cowley, K. L., Cohen, T., Andersen, S., Anibas, C., Glamore, W., Shenyang, C., Timms, W., & McMillan, T. (2019). The canary or the coalmine? Isotopic evidence of drying climate versus groundwater outflow as the cause for recent losses from Thirlmere Lakes, NSW. Paper presented to the Australasian Groundwater Conference, "Groundwater in a Changing World", 24 - 27 November 2019, Brisbane Convention and Exhibition Centre, Queensland. Retrieved from: http://www.groundwater.com.au/documents/agc2019-book-of-abstracts-updated.pdfen_AU
dc.identifier.conferenceenddate27 November 2019en_AU
dc.identifier.conferencenameAustralasian Groundwater Conference, 'Groundwater in a Changing World'en_AU
dc.identifier.conferenceplaceBrisbane, Queenslanden_AU
dc.identifier.conferencestartdate24 November 2019en_AU
dc.identifier.isbn978-1-925562-35-4en_AU
dc.identifier.urihttp://www.groundwater.com.au/documents/agc2019-book-of-abstracts-updated.pdfen_AU
dc.identifier.urihttps://apo.ansto.gov.au/dspace/handle/10238/11558en_AU
dc.language.isoenen_AU
dc.publisherNational Centre for Groundwater Research And Training, & Australian Chapter International Association Of Hydrogeologistsen_AU
dc.subjectLakesen_AU
dc.subjectNew South Walesen_AU
dc.subjectMiningen_AU
dc.subjectUnderground miningen_AU
dc.subjectAquifersen_AU
dc.subjectWatershedsen_AU
dc.subjectGeologic fracturesen_AU
dc.subjectClimatic changeen_AU
dc.subjectStable isotopesen_AU
dc.subjectEvaporationen_AU
dc.subjectRain wateren_AU
dc.titleThe canary or the coalmine? Isotopic evidence of drying climate versus groundwater outflow as the cause for recent losses from Thirlmere Lakes, NSWen_AU
dc.typeConference Abstracten_AU
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