In the Tintinara area, located south-east South Australia, airborne geophysics was recognized as<br>having potential to provide valuable biophysical data relevant to the management of irrigation<br>development and groundwater recharge reduction in the area. The groundwater of the area sustains<br>irrigation and other dryland agriculture. However the lifetime of this resource is limited by the leaching<br>of salt that has accumulated in the soil prior to land clearing and agricultural development. For some<br>areas, the groundwater may be saline and unusable for irrigation within ten to twenty years. The<br>presence or absence of a near surface clay unit can have an important influence on the rate and timing of<br>this deterioration by slowing recharge. Forward modelling suggested that a frequency domain helicopter<br>electromagnetic (HEM) system could map spatial variability associated with this unit. A survey was<br>conducted using the RESOLVE® HEM system and demonstrated that, through the use of a constrained<br>inversion approach, this unit could be mapped. This was confirmed with shallow drilling. We have<br>generated a product, namely clay thickness, which is now being used as an input into a hydrogeological<br>model to help predict recharge rates and influence management decisions in the area.
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