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Aquares Resistivity Surveys for Freshwater – Ground-Water Assessments

The proprietary acquisition and processing of Aquares Resistivity does not rely on either finite element or predefined layers, resulting in improved vertical and horizontal resolutions when compared to classical resistivity methods.

The improvement in vertical resolution between classical and Aquares resistivity is clearly seen here. From the Classical resistivity results (above) only a single aquifer can be seen, however from the Aquares results two aquifers can be defined.

Below is an example of classical and Aquares resistivity acquired along the same line, as part of a ground-water assessment. It can be clearly seen from the Aquares results (below) that there are two distinct plumes, not a single plume seen from the classically acquired and processed results (above). Here A resistivity survey was carried out across the Laak river near Tessenderlo in Belgium (september 2004). The aim of the survey was to map a saltwater contamination and to define the origin of the contamination. A previous resistivity survey carried out on exactly the same location and processed using finite element methods concluded that the Laak river carrying salt waste water from the Tessenderlo Chemical plant was responsible for infiltrating saltwater into the aquifer below

As this conclusion was incompatible with piezometric observations showing the general piezometric level of the aquifer to be higher than the Laak river level and observations regarding the silt sediments effectively sealing the riverbed, a second resistivity survey was requested using the Aquares resistivity method in order to avoid the horizontal and vertical smoothing effects of finite elements inversion.

The results of this survey are seen in the lower example . The same colour scale is used to visualise both survey results.

The Aquares results (below) see two distinct contamination plumes. The first plume at deeper levels shows an extremely low resistivity structure dipping towards the south. It was shown to be linked to a leaky salt water basin located north of the river. The salt water infiltrating at this basin is carried southward with the main groundwater current underneath the Laak river.
On top of the deep very low resistivity structure a shallower structure with slightly higher resistivities is clearly distinguished underneath the swamp south of the Laak river. This
low resistivity anomaly undoubtedly originates from the yearly Laak river inundations flooding the swamp with it’s salt water which than infiltrates into the subsurface.