Book/Dissertation / PhD Thesis

FZJ-2017-04645

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png High resolution imaging and modeling of aquifer structure

Güting, N. (Corresponding author)FZJ*

2017
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich
ISBN: 978-3-95806-253-5

Please use a persistent id in citations: http://hdl.handle.net/2128/15713  urn:nbn:de:0001-2017120719

Abstract: Predictive modeling of groundwater flow and solute transport can help to protect groundwater resources and to remediate contaminated sites. It is challenging, however,to develop realistic groundwater models because it is difficult to characterize and model the complex heterogeneity of geologic media. In this work, we propose an approach that combines high resolution geophysical imaging and multiple-point statistical modeling to estimate the 3-D structure of aquifers. Our study is carried out at the Krauthausen site, Germany, where 15 cross-boreholeground-penetrating radar (GPR) data sets were acquired in an all uvial sand and gravel aquifer. To analyze the GPR data, we apply a recently developed full-waveform inversion approach that is preferable, in terms of spatial resolution, over traditional ray based inversion approaches. By stitching together the inverted tomograms from adjacent crosshole planes, we are able to image, with a decimeter-scale resolution, the aquifer’s electrical properties (dielectric permittivity and electrical conductivity) along vertical cross-sections up to 50 m long and 10 m deep. Comparison of the GPR results with co-located direct-push profiles shows a strong correlation between the porosity derived from GPR dielectric permittivity and the porosity derived from direct-push neutron logs. We can show that the dielectric permittivity obtained from full-wave form inversion more accurately reconstructs sharp contrasts and fine-scale variations in porositythan the dielectric permittivity obtained from traditional ray-based inversion. One problem with using GPR for hydrogeological site characterization is that GPR yields electrical properties which are only indirectly linked to hydraulic properties. We present two approaches to estimate hydrogeological facies from the GPR results. The first approach, based on k-means cluster analysis, is applied to GPR data from five adjacent crosshole planes. Cluster analysis of the GPR results suggests three facies. Densely spaced cone penetration tests, located along the GPR transect, confirm the number of facies and their spatial distribution in the aquifer cross-section. Grain size distributions and flowmeter data, available from one of the boreholes, show that the derived facies boundaries correlate with changes in grain size and porosity, and to a lesser extent with changes in hydraulic conductivity.[...]

Note: Ruhr-Universität Bochum, Diss., 2017

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Contributing Institute(s):

1. Agrosphäre (IBG-3)

Research Program(s):

1. 255 - Terrestrial Systems: From Observation to Prediction (POF3-255) (POF3-255)

Appears in the scientific report 2017

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Database coverage:
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