An investigation of the hidden precious water resources of Dampier Peninsula using airborne electromagnetic method

Abstract

An airborne electromagnetic (AEM) survey was carried out over the Dampier Peninsula, North of Broome, WA during September-October, 2012. The key objectives of this geophysical survey funded by the Department of Water was (i) to obtain a better understanding of the nature of the contact between the base of the Broome Sandstone and the underlying siltstone; (ii) to identify areas of water retentive clay layers in the near surface, (iii) to create a map of the water table; (iv) to study the detailed geometry of the near shore saline intrusion; and thus (v) assist the conceptualisation of the hydrogeology and determine the quantity and quality of available groundwater resources for the benefit of local communities, government and industry. The survey was conducted using SkyTEM, a helicopter-borne time domain AEM system. The processed AEM data for each of the survey lines were examined and inverted using the industry standard inversion techniques. The results were then compared with available bore-hole geophysical logging as well as the regional geophysical, geological and hydrogeological data. Apart from successfully mapping the depth to water table for the whole project area, this survey has clearly delineated the thickness of Broome Sandstone, shallow impermeable layers within the Broome Sandstone and areas of possible saline sea water intrusions. The survey has also successfully identified a WNW-ESE trending lineament (a basement high) and couple of NW-SE trending structural features (such as fault structures) from the central part of the survey region. The regional geophysical data images obtained from Department of Mines & Petroleum supports this finding.