Publikationsdatum:
2020-08-12
Beschreibung:
Geophysical methods can characterize aquifer systems non-invasively and are particularly helpful to image the complex depositional structure of the subsurface.Among these, ground-penetrating radar (GPR) is an effective tool for detailed investigations of shallow subsurface geometry, but provides only limited information on hydraulic properties.Magnetic resonance tomography (MRT) provides the parameters such as water content (porosity) and relaxation time/hydraulic conductivity, but suffers from resolution limits. Furthermore, it requires knowledge of subsurface electrical resistivity, which can be obtained by electrical resistivity tomography (ERT) also suffering from resolution limits.To overcome the limitations in resolution, we incorporate GPR reflectors as structural information into the ERT and MRT data inversion.We test the methodology on a synthetic example and show improved imaging properties compared to standard inversion, particularly at larger depth, where resolution is limited.We apply the methodology to a test site that is characterized by a complex depositional structure. The Quaternary deposits consist of interbedded meltwater deposits (aquifers) and till (aquitards), overlain by aeolian deposits. To image the subsurface depositional structure in 3D, a 200 m × 250 m area was surveyed by GPR.The use of GPR constraints clearly improves the resolution and zonation of the subsurface image which is validated by drill-core analyses. We suggest a workflow to combine GPR, MRT and ERT, leading the way to high-resolution hydrogeological models that can be used for groundwater studies.
Print ISSN:
0016-8033
Digitale ISSN:
1942-2156
Thema:
Geologie und Paläontologie
,
Physik
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