Hydrochemical Processes in the Alluvial Aquifer of the Gwydir River (Northern New South Wales, Australia)

The hydrochemistry of the Narrabri Formation, the shallow aquifer system of the alluvial fan of the Gwydir River (NSW, Australia), is analyzed to better understand the hydrogeological processes involved in aquifer recharge, and to set up future management options that preserve the quantity and quality of water resources. Results show that groundwater hydrochemistry in this alluvial aquifer is mainly controlled by silicate weathering and cation exchange. However, salt remobilization in specific sedimentary layers within this alluvial fan deposit may locally increase groundwater salinity. Mixing between stream leakage and aquifer groundwater controls the hydrochemistry of water resources and produces a decrease in its salinity, which is beneficial for human uses.