Seminar

Groundwater plays an important role in supporting economic activity in South Australia and is sourced mainly from Tertiary sedimentary aquifers. In the city of Adelaide, abstraction has led to declining water levels and concerns exist over seawater intrusion along the coast. This presentation will provide an overview of the research that was conducted to characterise seawater intrusion and salinity sources in the main production aquifers of the greater Adelaide region. A regionally-extensive hypersaline groundwater body has been identified. Isotopic investigations have shown that this hypersaline groundwater most-likely has a meteoric origin and is at least 20,000 years old. Tidal investigations have further been conducted to characterise the hydraulic properties of several aquifers. The results show tidal influence up to 6 km inland, and important vertical variability of the propagation of the signal. Tidal fluctuations unconnected to marine tides appear to influence the water levels in certain parts of the system. Attention will also be paid to the offshore extension of the aquifer systems and the potential for the occurrence of low-salinity groundwater beneath the sea floor.