Geological heterogeneity and variations in groundwater composition can result in material properties and water concentrations varying over several orders of magnitude within small distances. Despite this reality of groundwater investigations, traditional hydrogeological assessments are generally restricted to point measurements of the subsurface at boreholes and, highly uncertain extrapolation is necessary to develop a conceptual model of the hydrogeology.
Geophysical methods can provide a spatially extensive complement to traditional hydrogeological investigations in locations where contrasts of the appropriate physical property exist in the subsurface. In academic and niche consulting environments, geophysical methods have been applied to improve groundwater understanding for decades. However, wider adoption of geophysics by the hydrogeological community is limited due to lack of technical knowledge, cost, equipment availability, and project budgets and time lines.
The purpose of this talk is to provide an overview of common geophysical methods used for groundwater investigations; highlight the pros/cons, relevant physical properties, and initiate a discussion on how greater application of geophysical methods can further our understanding of groundwater in Australia.
Two examples of geophysical groundwater investigations will be presented from both consulting and academic studies, ranging from low cost non-intrusive studies to high resolution time-lapse imaging of groundwater changes. The studies highlight the potential application of multiple geophysical methods and time-lapse geophysical monitoring, to provide insights into groundwater systems that are not otherwise available.