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Chloride Mass Balance recharge estimation, points dataset, McBride and Nulla basalt provinces

Created 17/10/2025

Updated 17/10/2025

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This dataset includes point estimates of groundwater recharge in mm/year. Recharge rates have been estimated at monitoring bore locations in the basaltic aquifers of the Nulla and McBride basalt provinces. Recharge estimates have been calculated using the “chloride mass balance” method. The chloride mass balance process assumes that the chloride ion is a conservative tracer in precipitation, evapotranspiration, recharge and runoff; and that all the chloride is from rainfall, instead of for example halite saturation or dissolution processes. So the volumetric water balance and the flux of chloride balance must both be true. Assuming that runoff and evapotranspiration are negligible (so approximated by zero), the equation is simplified: Water balance P=ET+R+Q Water balance multiplied by chloride concentrations (chloridefluxbalance) P∙Cl_ppt=ET∙Cl_ET+R∙Cl_gw+Q∙Cl_riv | ΔCl_reac≈0 Assumptions to simplify equation P∙Cl_ppt=R∙Cl_gw | Q≈0 & ET≈0 Rearranging for recharge rate (unknown) R=P∙(Cl_ppt)/(Cl_gw ) | Q≈0 & ET≈0 Where P = precipitation rate; ET = evapotranspiration rate; R = recharge rate; Q = runoff to streams; Clppt = concentration of Cl in precipitation; ClET = concentration of chloride in evapotranspiration; Clgw = concentration of Cl in groundwater; Clriv = concentration of chloride in river runoff; ΔClreac = change in chloride concentrations from reactions.

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Additional Info

Field Value
Title Chloride Mass Balance recharge estimation, points dataset, McBride and Nulla basalt provinces
Language eng
Licence Not Specified
Landing Page https://data.gov.au/data/en/dataset/46c38ade-0c86-47c7-99a3-c6a3501a7529
Contact Point
Geoscience Australia Data
clientservices@ga.gov.au
Reference Period 29/01/2020
Geospatial Coverage
Map data © OpenStreetMap contributors
{
  "coordinates": [
    [
      [
        143.5,
        -20.3
      ],
      [
        145.3,
        -20.3
      ],
      [
        145.3,
        -17.7
      ],
      [
        143.5,
        -17.7
      ],
      [
        143.5,
        -20.3
      ]
    ]
  ],
  "type": "Polygon"
}
Data Portal Geoscience Australia

Data Source

This dataset was originally found on Geoscience Australia "Chloride Mass Balance recharge estimation, points dataset, McBride and Nulla basalt provinces". Please visit the source to access the original metadata of the dataset:
https://ecat.ga.gov.au/geonetwork/srv/eng/csw/dataset/chloride-mass-balance-recharge-estimation-points-dataset-mcbride-and-nulla-basalt-provinces