TY - GEN

T1 - High resolution 3D imaging of subsurface using towed transient electromagnetic system - TTEM

T2 - 1st Indian Near Surface Geophysics Conference and Exhibition, INSG 2019

AU - Pedersen, Jesper

AU - Maurya, Pradip

AU - Christiansen, Anders Vest

AU - Auken, Esben

N1 - Funding Information: This research was supported by Innovation Fund Denmark, project rOpen and MapField, Central Region Denmark, and the InterReg project Topsoil. In addition, Aarhus University Centre for Water Technology (WATEC) has contributed. Publisher Copyright: © 2019 1st Indian Near Surface Geophysics Conference and Exhibition. All rights reserved.

PY - 2019

Y1 - 2019

N2 - Near surface geophysical methods are increasingly applied as a mapping tool in the areas of infrastructure, water supply, artificial infiltration, farming, waste deposits, construction, etc. A new towed geophysical transient electromagnetic system (tTEM) has been developed at Aarhus University (Maurya and Auken, in this conference) with a target zone of top 100 m of the subsurface. The development has been driven by the fact that geophysical methods capable of imaging this zone has limited efficiency when it comes to create full 3D images or they do not have sufficient imaging depth. In this paper, we present three case studies where the tTEM system was used for mapping the subsurface at hectare scale.In the first case, we used tTEM for mapping raw materials in the northern Jutland, Denmark. The survey was carried out to map possible sand and gravel deposits. In the tTEM models the gravel deposits show up as very high resistive bodies in the top 30 m. The deposits have significant lateral variation on a scale much less than hundred meter. In the second case study, the tTEM was used to map the thickness of a protecting clay layer above the groundwater aquifer in Vildbjerg, a town in central part of Denmark. Results shows that the top capping clay layer has sufficient thickness (>15 m) to protect the underlying aquifer from a pesticide pollution in the area. Finally, in the third case study, we used the tTEM system for mapping geology in the vicinity of a landfill. The inversion results reveal a hitherto unknown shallow buried valley-like feature within 30 m of the surface that was not identified from older, regional TEM surveys and that can be crucial for predicting the water flow. In the presentation, we will also present the comparison of the tTEM inversion result against the well-known electrical resistivity (ERT) method and borehole information.

AB - Near surface geophysical methods are increasingly applied as a mapping tool in the areas of infrastructure, water supply, artificial infiltration, farming, waste deposits, construction, etc. A new towed geophysical transient electromagnetic system (tTEM) has been developed at Aarhus University (Maurya and Auken, in this conference) with a target zone of top 100 m of the subsurface. The development has been driven by the fact that geophysical methods capable of imaging this zone has limited efficiency when it comes to create full 3D images or they do not have sufficient imaging depth. In this paper, we present three case studies where the tTEM system was used for mapping the subsurface at hectare scale.In the first case, we used tTEM for mapping raw materials in the northern Jutland, Denmark. The survey was carried out to map possible sand and gravel deposits. In the tTEM models the gravel deposits show up as very high resistive bodies in the top 30 m. The deposits have significant lateral variation on a scale much less than hundred meter. In the second case study, the tTEM was used to map the thickness of a protecting clay layer above the groundwater aquifer in Vildbjerg, a town in central part of Denmark. Results shows that the top capping clay layer has sufficient thickness (>15 m) to protect the underlying aquifer from a pesticide pollution in the area. Finally, in the third case study, we used the tTEM system for mapping geology in the vicinity of a landfill. The inversion results reveal a hitherto unknown shallow buried valley-like feature within 30 m of the surface that was not identified from older, regional TEM surveys and that can be crucial for predicting the water flow. In the presentation, we will also present the comparison of the tTEM inversion result against the well-known electrical resistivity (ERT) method and borehole information.

KW - 3D Imaging

KW - Electromagnetics

KW - HydroGeophysics

KW - Resistivity

KW - TEM

UR - http://www.scopus.com/inward/record.url?scp=85116221770&partnerID=8YFLogxK

U2 - 10.3997/2214-4609.201979040

DO - 10.3997/2214-4609.201979040

M3 - Article in proceedings

AN - SCOPUS:85116221770

T3 - 1st Indian Near Surface Geophysics Conference and Exhibition

SP - 245

EP - 250

BT - 1st Indian Near Surface Geophysics Conference and Exhibition

PB - European Association of Geoscientists and Engineers, EAGE

Y2 - 28 November 2019 through 29 November 2019

ER -