HR: 14:00h
AN: H13D-03    [Abstracts]
TI: Inverting Electromagnetic Data to Identify Soil Hydraulic Properties in Northern New South Wales, Australia
AU: * Vanags, C P
EM: cvanags@student.usyd.edu.au
AF: The University of Sydney, A03 Ross Street Building The University of Sydney, Sydney, NSW 2006 Australia
AU: Vervoort, R W
EM: w.vervoort@acss.usyd.edu.au
AF: The University of Sydney, A03 Ross Street Building The University of Sydney, Sydney, NSW 2006 Australia
AB: Pressure on water resources in Northern New South Wales, Australia has increased interest in water use efficiency, with variations in soil hydraulic properties being the main focus for management. Recent studies have shown that the clay-dominated alluvial plains commonly contain buried streams (often referred to as "palaeochannels" or "relict streams") which appear to have dramatic effects on subsurface water movement. Groundwater simulations are required for evaluating management options on potential sites; however their use is limited by a sparse 3-dimensional data set in Australia. Electromagnetic induction methods (EM) are a useful way to augment soil survey information, but they are traditionally limited to mapping lateral variations due to the nature of the equipment. In this research we use a combination of EM instruments at different frequencies and heights above the surface to delineate field-scale vadose zone heterogeneities which are likely to affect water movement. This paper compares various techniques for inverting the electromagnetic data including multiple linear regression, Tikhonov regularization, and 1-D inversion with lateral constraints. We will subsequently show how the different inversion techniques affect the behavior of a 2-D groundwater model based on 11 transects located within two differing management schemes. The results will help to explain effective sampling and measurement schemes for hydrological investigations in highly conductive areas with contrasting soil textures.
DE: 0604 Antenna arrays
DE: 0694 Instrumentation and techniques
DE: 0910 Data processing
DE: 3260 Inverse theory
SC: Hydrology [H]
MN: 2005 Joint Assembly