Groundwater flow and geochemical evolution in the Central Flinders Ranges, South Australia

Abstract

The chemical characteristics of water in the Oratunga Area, Central Flinders Ranges, South Australia have been used to evaluate and determine the processes controlling water chemistry in addition to the sources of ions. The isotopic analysis results show that the groundwater is mainly meteoric. Based on the rock and water chemistry, ionic ratios, hydrochemical facies and saturation indices, the chemical evolution has been studied. The chemistry of groundwater revealed two types of water. Thus, in high topographic areas, low TDS, bicarbonate and mixed water types are dominated and support a rapid and direct recharge. While in the low topographic areas, high TDS and chloride compositions are the most common attributed to the accumulation of ions and groundwater evolution. Analysis of the ion concentration, head data and saturation indices shows a compositional trend that can be studied as an evolutionary system. The ionic ratios and hydrogeochemical modelling using NETPATH was used to quantify and verify the different hydrochemical processes. The resulting data shows that calcite dissolution/precipitation and cation exchange reactions are the major processes affecting groundwater chemical evolution of the groundwater in the basin. This study has provided a basis for a better understanding of the hydrogeologic setting in areas of a little data.

Keywords: Australia; Flinders Ranges; Groundwater flow; Hydrochemistry; Modelling; Recharge; Stable isotopes.