ELECTRICAL RESISTIVITY EVALUATION OF SOUTH AUSTRALIAN MOUND SPRINGS

Mound Springs in South Australia provide the primary discharge mechanism for waters of the Great Artesian Basin (GAB) in the area. The GAB is the largest groundwater basin in Australia covering 22% of the continent. These springs are an important resource both for the environment and the Australian people, but their hydraulics are poorly defined. The springs have a range of morphologies and discharge rates and can include extensive tails (groundwater-dependent wetlands associated with the springs) and hundreds of springs in a given spring complex. Electrical Resistivity Imaging was used to evaluate mound spring subsurface characteristics. The results demonstrate that GAB water can appear as conductors or resistors in the subsurface and that the spring complexes have multiple discharge locations evident in the ERI data that are not easily observed at the surface. The hydrogeologic conceptual model developed from the ERI data provides a basis for hydraulic modeling of the mound springs.