Insights into recharge processes and speleothem proxy archives from long-term monitoring networks of cave drip water hydrology

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dc.contributor.authorBaker, AAen_AU
dc.contributor.authorTreble, PCen_AU
dc.contributor.authorHartmann, Aen_AU
dc.contributor.authorCuthbert, MOen_AU
dc.contributor.authorMarkowska, Men_AU
dc.contributor.authorBerthelin, Ren_AU
dc.contributor.authorTadros, CVen_AU
dc.contributor.authorLeopold, Men_AU
dc.contributor.authorHankin, SIen_AU
dc.date.accessioned2024-04-02T06:22:45Zen_AU
dc.date.available2024-04-02T06:22:45Zen_AU
dc.date.issued2020-05-04en_AU
dc.date.statistics2023-05-08en_AU
dc.description.abstractSince 2010 we have established cave drip water hydrological monitoring networks in four contrasting climate zones (Mediterranean, montane, semi-arid and sub-tropical) across continental Australia. Deploying over one hundred automated drip loggers, we combine these long-term monitoring datasets with climate and water isotope data, lidar mapping, electrical resistivity imaging and karst hydrological modelling to provide insights into recharge processes and the impact of hydrological variability on speleothem proxy archives. We identify increases in drip discharge and compare the timing of those events to antecedent climate conditions (rainfall, evapotranspiration). We find rainfall recharge thresholds vary with climate. At our montane site, recharge occurs after 13 to 31 mm rainfall events, depending on antecedent conditions. At the semi-arid site, recharge occurs after 40 mm rainfall events, and at our sub-tropical sites, recharge occurs following all instances where > 93 mm / week of precipitation occurs, with lower precipitation thresholds (down to 33 mm / week) possible depending on antecedent conditions and at sites with limited vegetation cover. We use these recharge thresholds to constrain simple soil moisture balance models to better understand soil and karst storage volumes. Combined with electrical resistivity imaging, we can relate recharge to the caves to subsurface water flow paths and karst water stores. At our montane and Mediterranean climate sites, relatively consistent drip water isotopic composition confirms the presence of well-mixed water stores. This allows us to quantify the extent of speleothem oxygen isotope variability due to fractionation associated with changes in drip rate. We identify significant differences in long-term mean drip rates between different drip sites within a cave, and significant differences in event-based drip rate responses within a cave. Drip hydrological variability helps explain the within-cave variability of speleothem oxygen isotope composition observed at both sites, and helps identify the primary drip water oxygen isotope signal. At our semi-arid site, drip water isotopic composition is dominated by epikarst evaporation and our drip water monitoring demonstrates that recharge events are infrequent (~1.6 per year). Using both observational and modelling data, we quantify the relative importance of evaporative fractionation in the epikarst and fractionation during calcite precipitation. Using modern speleothem samples, we demonstrate that the oxygen isotope signal in this water limited environment reflects the balance between the oxygen isotope composition of recharge and its subsequent fractionation in the soil, epikarst and cave. © Author(s) 2020. This work is distributed under the Creative Commons Attribution 4.0 Licence.en_AU
dc.identifier.citationBaker, A., Treble, P., Hartmann, A., Cuthbert, M., Markowska, M., Berthelin, R., Tadros, C., Leopold, M., & Hankin, S. (2020). Insights into recharge processes and speleothem proxy archives from long-term monitoring networks of cave drip water hydrology. Presentation to the EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1686. Retrieved from: https://doi.org/10.5194/egusphere-egu2020-1686en_AU
dc.identifier.conferenceenddate2020-05-08en_AU
dc.identifier.conferencenameEGU General Assembly 2020en_AU
dc.identifier.conferenceplaceOnlineen_AU
dc.identifier.conferencestartdate2020-05-04en_AU
dc.identifier.otherEGU2020-1686en_AU
dc.identifier.urihttps://doi.org/10.5194/egusphere-egu2020-1686en_AU
dc.identifier.urihttps://apo.ansto.gov.au/handle/10238/15544en_AU
dc.language.isoenen_AU
dc.publisherCopernicus GmbHen_AU
dc.relation.urihttps://doi.org/10.5194/egusphere-egu2020-1686en_AU
dc.subjectCavesen_AU
dc.subjectWateren_AU
dc.subjectHydrologyen_AU
dc.subjectAustraliaen_AU
dc.subjectClimatesen_AU
dc.subjectRainen_AU
dc.subjectMonitoringen_AU
dc.titleInsights into recharge processes and speleothem proxy archives from long-term monitoring networks of cave drip water hydrologyen_AU
dc.typeConference Abstracten_AU
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