Helicopter electromagnetic and magnetic geophysical survey data, Swedeburg and Sprague study areas, eastern Nebraska, May 2009

Smith, Bruce D.; Abraham, Jared D.; Cannia, James C.; Minsley, Burke J.; Ball, Lyndsay B.; Steele, Gregory V.; Deszcz-Pan, Maria

doi:10.3133/ofr20101288

Cited by 2 publications

(3 citation statements)

References 15 publications

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“…The FDEM system used in the present study was the RESOLVE system [53], which operated between 0.2 and 140 kHz and was towed approximately 30 m beneath a helicopter at a height of 30 m above ground. Survey speed was approximately 30 m/s and soundings were made every 3 m along flight lines, which were spaced ~280 m apart [53,54]. The survey footprint of the system is approximately 100 m, but footprint size varies with frequency, survey altitude, and resistivity [55,56].…”

Section: Airborne Electromagnetic (Aem) Methodsmentioning

confidence: 99%

“…The survey footprint of the system is approximately 100 m, but footprint size varies with frequency, survey altitude, and resistivity [55,56]. Geophysical inversion of this dataset [53,54] was accomplished using a regularized least-squares inversion algorithm in the program EM1DFM [57,58]. This 1D, layered-earth model fits a response to the data by minimizing the objective function (Φ) given as follows:…”

Section: Airborne Electromagnetic (Aem) Methodsmentioning

confidence: 99%

“…GCV was chosen only after evaluating multiple inversions of the same data using different methods for determining β [57]. Further details on the procedures used to select inversion parameters are in a published report [54]. Resistivity-depth models containing 25 layers were produced for each sounding point in the study area ( Figure 3).…”

Section: Airborne Electromagnetic (Aem) Methodsmentioning

confidence: 99%

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Combining Hydraulic Head Analysis with Airborne Electromagnetics to Detect and Map Impermeable Aquifer Boundaries

Korus

2018

Water

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Impermeable aquifer boundaries affect the flow of groundwater, transport of contaminants, and the drawdown of water levels in response to pumping. Hydraulic methods can detect the presence of such boundaries, but these methods are not suited for mapping complex, 3D geological bodies. Airborne electromagnetic (AEM) methods produce 3D geophysical images of the subsurface at depths relevant to most groundwater investigations. Interpreting a geophysical model requires supporting information, and hydraulic heads offer the most direct means of assessing the hydrostratigraphic function of interpreted geological units. This paper presents three examples of combined hydraulic and AEM analysis of impermeable boundaries in glacial deposits of eastern Nebraska, USA. Impermeable boundaries were detected in a long-term hydrograph from an observation well, a short-duration pumping test, and a water table map. AEM methods, including frequency-domain and time-domain AEM, successfully imaged the impermeable boundaries, providing additional details about the lateral extent of the geological bodies. Hydraulic head analysis can be used to verify the hydrostratigraphic interpretation of AEM, aid in the correlation of boundaries through areas of noisy AEM data, and inform the design of AEM surveys at local to regional scales.

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Section: Airborne Electromagnetic (Aem) Methodsmentioning

confidence: 99%

Section: Airborne Electromagnetic (Aem) Methodsmentioning

confidence: 99%

Section: Airborne Electromagnetic (Aem) Methodsmentioning

confidence: 99%

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Combining Hydraulic Head Analysis with Airborne Electromagnetics to Detect and Map Impermeable Aquifer Boundaries

Korus

2018

Water

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Three‐dimensional architecture and hydrostratigraphy of cross‐cutting buried valleys using airborne electromagnetics, glaciated Central Lowlands, Nebraska, USA

et al. 2016

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Buried valleys are characteristic features of glaciated landscapes, and their deposits host important aquifers worldwide. Understanding the stratigraphic architecture of these deposits is essential for protecting groundwater and interpreting sedimentary processes in subglacial and ice-marginal environments. The relationships between depositional architecture, topography and hydrostratigraphy in dissected, pre-Illinoian till sheets is poorly understood. Boreholes alone are inadequate to characterize the complex geology of buried valleys, but airborne electromagnetic surveys have proven useful for this purpose. A key question is whether the sedimentary architecture of buried valleys can be interpreted from airborne electromagnetic profiles. This study employs airborne electromagnetic resistivity profiles to interpret the threedimensional sedimentary architecture of cross-cutting buried valleys in a ca 400 km 2 area along the western margin of Laurentide glaciation in North America. A progenitor bedrock valley is succeeded by at least five generations of tunnel valleys that become progressively younger northward. Tunnel-valley infills are highly variable, reflecting under-filled and over-filled conditions. Under-filled tunnel valleys are expressed on the modern landscape and contain fine sediments that act as hydraulic barriers. Over-filled tunnel valleys are not recognized in the modern landscape, but where they are present they form hydraulic windows between deep aquifer units and the land surface. The interpretation of tunnel-valley genesis herein provides evidence of the relationships between depositional processes and glacial landforms in a dissected, pre-Illinoian till sheet, and contributes to the understanding of the complex physical hydrology of glacial aquifers in general.

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Helicopter electromagnetic and magnetic geophysical survey data, Swedeburg and Sprague study areas, eastern Nebraska, May 2009

Cited by 2 publications

References 15 publications

Combining Hydraulic Head Analysis with Airborne Electromagnetics to Detect and Map Impermeable Aquifer Boundaries

Combining Hydraulic Head Analysis with Airborne Electromagnetics to Detect and Map Impermeable Aquifer Boundaries

Three‐dimensional architecture and hydrostratigraphy of cross‐cutting buried valleys using airborne electromagnetics, glaciated Central Lowlands, Nebraska, USA

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