The hydrogeology of the Melbourne Area is complex. The area includes the Tertiary Port Phillip Basin and the underlying and surrounding older predominantly Siluro-Ordovician bedrock and Devonian granitic rocks. The Port Phillip Basin contains a system of aquifers separated by aquitards. The aquifers are varyingly hydraulically interconnected. The Werribee and Bridgewater formations are the most productive aquifers. Important aquifers occur in the Brighton Group, basalts of both the Older Volcanics and Newer Volcanics, and deltaic deposits of the Werribee and Yarra rivers.
Knowledge of groundwater occurrence, aquifer types and hydraulic parameters, and groundwater chemistry is critical for most if not all civil engineering projects. This paper provides an overview of the hydrogeology of the Melbourne area. The location of major aquifers (and aquitards) is broadly mapped, aquifer types are identified and hydraulic parameters and groundwater chemistry in the different hydrostratigraphic units summarized. It is emphasized that the information provided is very generalized and that more detailed information based on local and site specific investigations are required to fully assess the impact of groundwater on proposed civil engineering projects and the impact of proposed projects on groundwater.