Airborne Electromagnetic, Magnetic, and Radiometric Surveys at the German North Sea Coast Applied to Groundwater and Soil Investigations

Siemon, B.; Seht, M. Ibs-von; Steuer, A.; Deus, Nico; Wiederhold, H.

doi:10.3390/rs12101629

Cited by 16 publications

(9 citation statements)

References 64 publications

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“…Remote sensing and airborne geophysical techniques represent the most suitable means to investigate peatlands at a large scale (>10 km 2 ). Several recent studies have successfully used airborne electromagnetic (AEM) methods to estimate peatland thickness and extent [14][15][16][17]. Likewise, different proximal or ground-based geophysical sensors have been accurately applied to map peat properties at smaller scales.…”

Section: Introductionmentioning

confidence: 99%

Mapping of Peat Thickness Using a Multi-Receiver Electromagnetic Induction Instrument

Beucher¹,

Koganti²,

Iversen³

et al. 2020

Remote Sensing

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Peatlands constitute extremely valuable areas because of their ability to store large amounts of soil organic carbon (SOC). Investigating different key peat soil properties, such as the extent, thickness (or depth to mineral soil) and bulk density, is highly relevant for the precise calculation of the amount of stored SOC at the field scale. However, conventional peat coring surveys are both labor-intensive and time-consuming, and indirect mapping methods based on proximal sensors appear as a powerful supplement to traditional surveys. The aim of the present study was to assess the use of a non-invasive electromagnetic induction (EMI) technique as an augmentation to a traditional peat coring survey that provides localized and discrete measurements. In particular, a DUALEM-421S instrument was used to measure the apparent electrical conductivity (ECa) over a 10-ha field located in Jutland, Denmark. In the study area, the peat thickness varied notably from north to south, with a range from 3 to 730 cm. Simple and multiple linear regressions with soil observations from 110 sites were used to predict peat thickness from (a) raw ECa measurements (i.e., single and multiple-coil predictions), (b) true electrical conductivity (σ) estimates calculated using a quasi-three-dimensional inversion algorithm and (c) different combinations of ECa data with environmental covariates (i.e., light detection and ranging (LiDAR)-based elevation and derived terrain attributes). The results indicated that raw ECa data can already constitute relevant predictors for peat thickness in the study area, with single-coil predictions yielding substantial accuracies with coefficients of determination (R2) ranging from 0.63 to 0.86 and root mean square error (RMSE) values between 74 and 122 cm, depending on the measuring DUALEM-421S coil configuration. While the combinations of ECa data (both single and multiple-coil) with elevation generally provided slightly higher accuracies, the uncertainty estimates for single-coil predictions were smaller (i.e., smaller 95% confidence intervals). The present study demonstrates a high potential for EMI data to be used for peat thickness mapping.

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Section: Introductionmentioning

confidence: 99%

Mapping of Peat Thickness Using a Multi-Receiver Electromagnetic Induction Instrument

Beucher¹,

Koganti²,

Iversen³

et al. 2020

Remote Sensing

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“…The high EC of clay leads to the general challenge of distinguishing freshwater saturated clays from brackish water saturated sands that may have very similar EC values. Gamma radiation of potassium, thorium and uranium at the surface helps to distinguish between clayey and sandy sediments (Siemon et al, 2020), as does an acoustic impedance contrast that seismic methods can show.…”

Section: Geophysical Methodsmentioning

confidence: 99%

A State-Of-The-Art Perspective on the Characterization of Subterranean Estuaries at the Regional Scale

et al. 2021

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Subterranean estuaries the, subsurface mixing zones of terrestrial groundwater and seawater, substantially influence solute fluxes to the oceans. Solutes brought by groundwater from land and solutes brought from the sea can undergo biogeochemical reactions. These are often mediated by microbes and controlled by reactions with coastal sediments, and determine the composition of fluids discharging from STEs (i.e., submarine groundwater discharge), which may have consequences showing in coastal ecosystems. While at the local scale (meters), processes have been intensively studied, the impact of subterranean estuary processes on solute fluxes to the coastal ocean remains poorly constrained at the regional scale (kilometers). In the present communication, we review the processes that occur in STEs, focusing mainly on fluid flow and biogeochemical transformations of nitrogen, phosphorus, carbon, sulfur and trace metals. We highlight the spatio-temporal dynamics and measurable manifestations of those processes. The objective of this contribution is to provide a perspective on how tracer studies, geophysical methods, remote sensing and hydrogeological modeling could exploit such manifestations to estimate the regional-scale impact of processes in STEs on solute fluxes to the coastal ocean.

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“…BGR conducted airborne surveys covering the entire study area, simultaneously recording electromagnetic, magnetic, and radiometric data (Siemon et al 2020). The electromagnetic data used here were acquired in 2000 for the Cuxhaven area (Siemon et al 2013), in 2001 for the Bremerhaven area (Siemon et al 2011(Siemon et al ), in 2004 for the Hadelner Marsch area (Siemon et al 2017(Siemon et al ) and in 2008(Siemon et al -2010 for the Glückstadt area (Steuer et al 2013), all available at Produktcenter BGR (2017).…”

Section: Assigning Formation Factor To Hem Data At Different Depthsmentioning

confidence: 99%

Coastal groundwater systems: mapping chloride distribution from borehole and geophysical data

Rahman¹,

Zhao²,

Wiederhold

et al. 2021

Grundwasser - Zeitschrift der Fachsektion Hydrogeologie

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Information on chloride (Cl) distribution in aquifers is essential for planning and management of coastal zone groundwater resources as well as for simulation and validation of density-driven groundwater models. We developed a method to derive chloride concentrations from borehole information and helicopter-borne electromagnetic (HEM) data for the coastal aquifer in the Elbe-Weser region where observed chloride and electrical conductivity data reveal that the horizontal distribution of salinity is not uniform and does not correlate with the coastline. The integrated approach uses HEM resistivity data, borehole petrography information, grain size analysis of borehole samples as well as observed chloride and electrical conductivity to estimate Cl distribution. The approch is not straightforward due to the complex nature of the geology where clay and silt are present. Possible errors and uncertainties involved at different steps of the method are discussed.

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Airborne Electromagnetic, Magnetic, and Radiometric Surveys at the German North Sea Coast Applied to Groundwater and Soil Investigations

Cited by 16 publications

References 64 publications

Mapping of Peat Thickness Using a Multi-Receiver Electromagnetic Induction Instrument

Mapping of Peat Thickness Using a Multi-Receiver Electromagnetic Induction Instrument

A State-Of-The-Art Perspective on the Characterization of Subterranean Estuaries at the Regional Scale

Coastal groundwater systems: mapping chloride distribution from borehole and geophysical data

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