Fractured Rock Geophysical Studies In The Clare Valley, South Australia

Groundwater in the Clare Valley, South Australia is drawn from fractured rock aquifers.<br>Acquiring reliable groundwater sources in fractured rock aquifers is complicated by the<br>irregular distribution of fractures, causing large spatial variation in bore yield. With the rapid<br>development of new vineyards of recent years expected to continue, the issue of sustainable<br>resource management is of utmost importance. The primary object of this paper is to develop<br>existing geophysical field techniques and data interpretation to assist in defining preferential<br>flow paths due to hydraulically conductive fractures, and thus assist defining capture zones of<br>irrigation bores in the Clare Valley.<br>Detailed surface azimuthal resistivity surveys utilising DC resistivity and EM induction<br>methods were performed at a number of locations to determine electronic (and thus<br>hydraulic) anisotropy and heterogeneity. Strong electrical anisotropies were detected with<br>both methods. A mise a la masse survey was also carried out at one site with a down hole<br>current source and a roving potential electrode.<br>The success of the project has been two-fold. Firstly, the geophysical methods employed<br>have shown excellent potential to provide important information in the determination of<br>capture zones of irrigation bores when combined with other hydrogeological information.<br>Secondly, improvements in geophysical field methods and data interpretation have been<br>developed, with the potential to be applied to future studies of fractured rock aquifers.