In light of anticipated further development in regional areas and subsequent increases in demand for water, a better understanding of South Australia’s non-prescribed groundwater resources is required. There is also uncertainty of the impacts associated with a changing climate on the groundwater resources, existing developments and groundwater dependent ecosystems. As the lead agency for water resources management in South Australia, DEWNR undertakes groundwater assessments aimed at identifying new sources of water and improving our understanding of developed resources to ensure they are appropriately managed.
The Willochra Basin extends north from Melrose in the Flinders Ranges. Good quality groundwater (<1000 mg/L) in the southern half of the basin has been developed for town water supply, lucerne irrigation and stock and domestic supplies. However, the extent and recharge rate of good quality groundwater has remained uncertain. In this study, water level, salinity, hydrochemistry and radiocarbon age data were acquired to improve the conceptual understanding of the basins’ hydrogeology and groundwater recharge processes.
Potentiometric contours and salinity maps have been refined. Hydrogeochemistry data and radiocarbon age dating have helped elucidate recharge processes and groundwater flow paths. Major ion analysis suggests recharge to the fractured rock aquifers in the streambed of Spring Creek, and from there it then flows into the basins’ confined aquifer. All lines of evidence support a revised conceptual model of contemporary recharge of good quality water in the current climate.
The results of this study have reshaped the conceptualisation of recharge processes and groundwater flow paths of Willochra Basin. The identification of contemporary streambed recharge implies climate dependency on sustainable groundwater resource development. The sustainability of future extractions should be evaluated in light of the new knowledge.