Characterization of the subsurface architecture and identification of potential groundwater paths in a clay-rich floodplain using multi-electrode resistivity imaging
- Authors: Guinea, Ander , Hollins, Suzanne , Meredith, Karina , Hankin, Stuart , Cendón, Dioni
- Date: 2018
- Type: Text , Journal article
- Relation: Hydrological Sciences Journal Vol. 63, no. 6 (2018), p. 909-925
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- Description: The interaction between surface water and groundwater in clay-rich fluvial environments can be complex and is generally poorly understood. Airborne electromagnetic surveys are often used for characterizing regional groundwater systems, but they are constrained by the resolution of the method. A resistivity imaging survey has been carried out in the Macquarie Marshes (New South Wales, Australia) in combination with water chemical sampling. The results have enabled the identification of buried palaeochannels and the location of potential recharge points. The data have been compared with previously published airborne electromagnetic data in the same area. Deeper less conductive features suggest that there is a potential connection between the Great Artesian Basin and groundwater contained within the shallow sand aquifer. Even though the chemistry of the groundwater samples does not indicate interaction with the Great Artesian Basin, the observed discontinuity in the saprolite implies potential for this to happen in other locations.
Geoelectrical characterization of hydrological processes in a buried braided river system
- Authors: Guinea, Ander , Hollins, Suzanne , Meredith, Karina , Hankin, Stuart , Cendón, Dioni
- Date: 2016
- Type: Text , Conference proceedings , Conference paper
- Relation: 22nd European Meeting of Environmental and Engineering Geophysics, Near Surface Geoscience 2016; Barcelona, Spain; 4th-8th September 2016
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- Description: The Macquarie Marshes (NSW, Australia) cover approximately 200 square km of the Macquarie River flood-plains. The marshes are one of the largest remaining inland semi-permanent wetlands in southeastern Australia. Diversity of fauna and flora has decreased in the wetlands while the flood-drought cycles controlling these ecosystems have been affected by recent human activity. An Electrical Resistivity Tomography survey has been carried out to provide insight into the surface water/ groundwater interactions occurring at the north-western part of the marshes and to identify potential recharge areas of the aquifer systems. In the resistivity sections three main units can be identified: 1. A top unit of low-resistivity (1 to 6 ohm.m) with about 5 meter thick on average. 2. A middle unit of higher electrical resistivity (6 to 20 ohm.m) that continues to a depth of approximately 20 metres and is discontinuous laterally. 3. A bottom unit below a depth of 20 to 25 metres with resistivity decreasing to values similar to those of the top unit. The resistivity results has allowed to identify clay dominated and sand dominated materials. The groundwater is recharged from surface water following sandy windows in the clay created by modern channels on the surface of the marshes.
- Description: 22nd European Meeting of Environmental and Engineering Geophysics, Near Surface Geoscience 2016