TY - JOUR

T1 - Magnetic resonance tomography constrained by ground-penetrating radar for improved hydrogeophysical characterization

AU - Jiang, Chuandong

AU - Igel, Jan

AU - Dlugosch, Raphael

AU - Müller-petke, Mike

AU - Günther, Thomas

AU - Helms, Julian

AU - Lang, Jörg

AU - Winsemann, Jutta

N1 - Funding Information: C. Jiang was supported by the International Postdoctoral Exchange Fellowship Program of China (no. 20160057) and National Natural Science Foundation of China (no. 201604083). We would like to thank the State Authority for Mining, Energy and Geology in Lower Saxony, Germany, for the drillings; D. Epping, V. Kipke, R. Meyer, and P. Skiba for supporting the geophysical field surveys; and the German Federal Institute for Geosciences and Natural Resources and C. Müller for carrying out the grain-size analyses. We thank C. Brandes and F. Binot for the discussion on geology.

PY - 2020/11/1

Y1 - 2020/11/1

N2 - Geophysical methods can characterize aquifer systems noninvasively and are particularly helpful to image the complex depositional architecture of the subsurface. Among these, ground-penetrating radar (GPR) is an effective tool for detailed investigations of shallow subsurface geometry, but it provides only limited information on hydraulic properties. Magnetic resonance tomography (MRT) provides parameters such as water content (porosity) and relaxation time/hydraulic conductivity, but it 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 have incorporated GPR reflectors as structural information into the ERT and MRT data inversion. We test the methodology on a synthetic example and find improved imaging properties compared to standard inversion, particularly at greater depths, where the resolution is limited. We apply the methodology to a test site that is characterized by a complex depositional architecture. The Quaternary deposits consist of interbedded meltwater deposits (aquifers) and till (aquitards), overlain by aeolian deposits. To image the subsurface depositional architecture in three dimensions, a 200 × 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 develop a workflow to combine GPR, MRT, and ERT, leading the way to high-resolution hydrogeologic models that can be used for groundwater studies.

AB - Geophysical methods can characterize aquifer systems noninvasively and are particularly helpful to image the complex depositional architecture of the subsurface. Among these, ground-penetrating radar (GPR) is an effective tool for detailed investigations of shallow subsurface geometry, but it provides only limited information on hydraulic properties. Magnetic resonance tomography (MRT) provides parameters such as water content (porosity) and relaxation time/hydraulic conductivity, but it 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 have incorporated GPR reflectors as structural information into the ERT and MRT data inversion. We test the methodology on a synthetic example and find improved imaging properties compared to standard inversion, particularly at greater depths, where the resolution is limited. We apply the methodology to a test site that is characterized by a complex depositional architecture. The Quaternary deposits consist of interbedded meltwater deposits (aquifers) and till (aquitards), overlain by aeolian deposits. To image the subsurface depositional architecture in three dimensions, a 200 × 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 develop a workflow to combine GPR, MRT, and ERT, leading the way to high-resolution hydrogeologic models that can be used for groundwater studies.

UR - http://www.scopus.com/inward/record.url?scp=85111383954&partnerID=8YFLogxK

U2 - 10.1190/geo2020-0052.1

DO - 10.1190/geo2020-0052.1

M3 - Article

VL - 85

SP - JM13-JM26

JO - Geophysics

JF - Geophysics

SN - 0016-8033

IS - 6

ER -