Geological controls on the spatial variability of groundwater recharge and salinity in a regional-scale basalt aquifer in western Victoria

摘要

Airborne geophysical images have been used in combination with analyses of inert and reactive tracers in groundwaters to study the impact of aquifer lithology on the distribution of preferential recharge areas and recharge rates in a regional scale basalt aquifer in the eastern Hopkins catchment, western Victoria. Groundwater quality within this aquifer ranges from fresh water suitable for human consumption to saline brines. The results of the study show that the freshest groundwaters are generally found in close proximity to volcanoes, and that these groundwaters are mostly modern as a result of preferential recharge through the younger basalts and major eruption points (recharge rates up to about 50 mm/year). Recharge rates decrease to less than 1 mm/year through the thick clay-rich soil profiles of the older basalts, and groundwaters in these aquifers are therefore older and more saline.