Age and origin of fresh groundwater in the southwest Murray basin

By using a combination of isotopic and chemical techniques, the fresh groundwater in the Southwest Murray Basin has been shown to originate from palaeo-recharge during a relatively wet period approximately 4,000-8,000 years ago. The area of freshwater resulted from direct recharge through the sandy soils of the Big and Little Deserts. Historically, the recharge rate has been greater in the Little Desert than the Big Desert and continued to be high until about 4,000 years ago. For areas to the north of the Big Desert, there is no evidence of high recharge during the last 20,000 years.