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To investigate subsurface features in the Lower Havel River floodplain, we conducted Electrical Resistivity Tomography (ERT) transects and Electromagnetic Induction (EMI) surveys at three different depths in 2023 and 2024. These near surface geophysical methods were complemented by 24 driving core drillings to relate the electrical properties with sedimentological characteristics. Additionally, five selected sediment cores were used for subsequent geochemical lab analyses (grain size, CNS, TOC, TIC). Electromagnetic induction (EMI) was measured with a CMD-Mini Explorer (GF Instruments s.r.o., Brno, Czech Republic) in June 2023 and June 2024. We used the vertical dipole (VDP) at coil spacings of 0.32 m (VDP1), 0.71 m (VDP2) and 1.18 m (VDP3), archieving effective penetration depths of 0.5 m (VDP1), 1.0 m (VDP2) and 1.8 m (VDP3). According to the manufacturer, 70% of the signal originate from above these depths. The EMI sensors measure the apparent electrical conductivity (ECa, in mS/m). Measurements were taken by carrying the instrument about 0.2 m above ground while being directly connected to D-GPS (Leica GPS1200) for positioning. The acquisition rate was five measurements per second. Data quality was checked by measuring a reference line before and after each measurement. The area investigated by EMI in June 2023 is located to the north and northeast of the Gülpe research station. It has a total area of 12.3 ha. The reference line was located in the southern part of the study area. No drift correction had to be applied due to good data quality. Reference lines and single outliers were removed. The area investigated by EMI in June 2024 is located southeast of the research station. The survey area there is 8.1 ha in size. The reference line for the measurements there was located in the north-westernmost area of the site. No drift correction had to be applied due to good data quality. Reference lines and single outliers were removed. The Electrical Resistivity Tomography (ERT) data were acquired by using a PC controlled DC resistivity meter system (RESECS, Geoserve, Kiel, Germany). In total, we measured four ERT transects. Two transects in June 2023, where transect 1 had a total length of 259 m with an electrode spacing of 0.5 m and transect 2 had a total length of 223 m with an electrode spacing of 1 m. The measurements in 2023 were carried out under extreme dry conditions. Two further transects were measured in June 2024 with an electrode spacing of 1m, transect 3 with a total length of 207 m and transect 4 with a total length of 239 m. We applied wenner alpha and dipol-dipol configuration. The coordinates and the height of the electrodes were measured with a D-GPS (2023: TOPCON HiPer II / 2024: Leica GPS1200). Sediment cores were recovered using a hand-held Cobra Pro (Atlas Copco) core drilling system with a 60 mm diameter open corer. One-meter segments were retrieved and assessed in the field for sedimentological features, including estimations of grain size, carbonate content, humus content, and redox features (AG Boden 2005, 2024). Colour descriptions were carried out using the Munsell Soil Color Chart. The exact positions of the drilling points were recorded using a differential GPS device (TOPCON HiPer II). The cores were photographed, documented and sampled at 5–10 cm intervals for subsequent laboratory analyses. Bulk samples from five selected cores (RK1, RK3, RK13, RK15, RK17) were freeze-dried, sieved (2 mm), and weighed. Total carbon (TC), total nitrogen (TN), and total sulfur (TS) contents were measured using a CNS analyzer (Vario EL cube, Elementar). Inorganic carbon (TIC) was determined using calcimeter measurements (Scheibler method, Eijkelkamp). Organic carbon (TOC) was calculated as TOC = TC − TIC. For the grain size analyses, sediment samples were first sieved to <2 mm and subsamples of 10 g were treated with 50 ml of 35% hydrogen peroxide (H₂O₂) and gently heated to remove organic matter. Following this, 10 ml of 0.4 N sodium pyrophosphate solution (Na₄P₂O₇) was added to disperse the particles, and the suspension was subjected to ultrasonic treatment for 45 minutes. The sand fraction was analysed by dry sieving and classified into four size classes: coarse sand (2000–630 µm), medium sand (630–200 µm), fine sand (200–125 µm), and very fine sand (125–63 µm). Finer fractions were determined using X-ray granulometry (XRG) with a SediGraph III 5120 (Micromeritics). These included coarse silt (63–20 µm), medium silt (20–6.3 µm), fine silt (6.3–2.0 µm), coarse clay (2.0–0.6 µm), medium clay (0.6–0.2 µm), and fine clay (<0.2 µm).
Electromagnetic induction (EMI) was measured with a CMD-Mini Explorer (GF Instruments s.r.o., Brno, Czech Republic) in June 2023. We used the vertical dipole (VDP) at coil spacings of 0.32 m (VDP1), 0.71 m (VDP2) and 1.18 m (VDP3), archieving effective penetration depths of 0.5 m (VDP1), 1.0 m (VDP2) and 1.8 m (VDP3). According to the manufacturer, 70% of the signal originate from above these depths. The EMI sensors measure the apparent electrical conductivity (ECa, in mS/m). Measurements were taken by carrying the instrument about 0.2 m above ground while being directly connected to D-GPS (Leica GPS1200) for positioning. The acquisition rate was five measurements per second. Data quality was checked by measuring a reference line before and after each measurement. The area investigated by EMI in June 2023 is located to the north and northeast of the Gülpe research station. It has a total area of 12.3 ha. The reference line was located in the southern part of the study area. No drift correction had to be applied due to good data quality. Reference lines and single outliers were removed. The data set contains the EMI data with an intercoil spacing of 0.71 m.
Electromagnetic induction (EMI) was measured with a CMD-Mini Explorer (GF Instruments s.r.o., Brno, Czech Republic) in June 2024. We used the vertical dipole (VDP) at coil spacings of 0.32 m (VDP1), 0.71 m (VDP2) and 1.18 m (VDP3), archieving effective penetration depths of 0.5 m (VDP1), 1.0 m (VDP2) and 1.8 m (VDP3). According to the manufacturer, 70% of the signal originate from above these depths. The EMI sensors measure the apparent electrical conductivity (ECa, in mS/m). Measurements were taken by carrying the instrument about 0.2 m above ground while being directly connected to D-GPS (Leica GPS1200) for positioning. The acquisition rate was five measurements per second. Data quality was checked by measuring a reference line before and after each measurement. The area investigated by EMI in June 2024 is located southeast of the research station. The survey area there is 8.1 ha in size. The reference line for the measurements there was located in the north-westernmost area of the site. No drift correction had to be applied due to good data quality. Reference lines and single outliers were removed. The data set contains the EMI data with an intercoil spacing of 0.32 m.
Electromagnetic induction (EMI) was measured with a CMD-Mini Explorer (GF Instruments s.r.o., Brno, Czech Republic) in June 2024. We used the vertical dipole (VDP) at coil spacings of 0.32 m (VDP1), 0.71 m (VDP2) and 1.18 m (VDP3), archieving effective penetration depths of 0.5 m (VDP1), 1.0 m (VDP2) and 1.8 m (VDP3). According to the manufacturer, 70% of the signal originate from above these depths. The EMI sensors measure the apparent electrical conductivity (ECa, in mS/m). Measurements were taken by carrying the instrument about 0.2 m above ground while being directly connected to D-GPS (Leica GPS1200) for positioning. The acquisition rate was five measurements per second. Data quality was checked by measuring a reference line before and after each measurement. The area investigated by EMI in June 2024 is located southeast of the research station. The survey area there is 8.1 ha in size. The reference line for the measurements there was located in the north-westernmost area of the site. No drift correction had to be applied due to good data quality. Reference lines and single outliers were removed. The data set contains the EMI data with an intercoil spacing of 1.18 m.
Electromagnetic induction (EMI) was measured with a CMD-Mini Explorer (GF Instruments s.r.o., Brno, Czech Republic) in June 2024. We used the vertical dipole (VDP) at coil spacings of 0.32 m (VDP1), 0.71 m (VDP2) and 1.18 m (VDP3), archieving effective penetration depths of 0.5 m (VDP1), 1.0 m (VDP2) and 1.8 m (VDP3). According to the manufacturer, 70% of the signal originate from above these depths. The EMI sensors measure the apparent electrical conductivity (ECa, in mS/m). Measurements were taken by carrying the instrument about 0.2 m above ground while being directly connected to D-GPS (Leica GPS1200) for positioning. The acquisition rate was five measurements per second. Data quality was checked by measuring a reference line before and after each measurement. The area investigated by EMI in June 2024 is located southeast of the research station. The survey area there is 8.1 ha in size. The reference line for the measurements there was located in the north-westernmost area of the site. No drift correction had to be applied due to good data quality. Reference lines and single outliers were removed. The data set contains the EMI data with an intercoil spacing of 0.71m.
Electromagnetic induction (EMI) was measured with a CMD-Mini Explorer (GF Instruments s.r.o., Brno, Czech Republic) in June 2023. We used the vertical dipole (VDP) at coil spacings of 0.32 m (VDP1), 0.71 m (VDP2) and 1.18 m (VDP3), archieving effective penetration depths of 0.5 m (VDP1), 1.0 m (VDP2) and 1.8 m (VDP3). According to the manufacturer, 70% of the signal originate from above these depths. The EMI sensors measure the apparent electrical conductivity (ECa, in mS/m). Measurements were taken by carrying the instrument about 0.2 m above ground while being directly connected to D-GPS (Leica GPS1200) for positioning. The acquisition rate was five measurements per second. Data quality was checked by measuring a reference line before and after each measurement. The area investigated by EMI in June 2023 is located to the north and northeast of the Gülpe research station. It has a total area of 12.3 ha. The reference line was located in the southern part of the study area. No drift correction had to be applied due to good data quality. Reference lines and single outliers were removed. The data set contains the EMI data with an intercoil spacing of 1.18 m.
Electromagnetic induction (EMI) was measured with a CMD-Mini Explorer (GF Instruments s.r.o., Brno, Czech Republic) in June 2023. We used the vertical dipole (VDP) at coil spacings of 0.32 m (VDP1), 0.71 m (VDP2) and 1.18 m (VDP3), archieving effective penetration depths of 0.5 m (VDP1), 1.0 m (VDP2) and 1.8 m (VDP3). According to the manufacturer, 70% of the signal originate from above these depths. The EMI sensors measure the apparent electrical conductivity (ECa, in mS/m). Measurements were taken by carrying the instrument about 0.2 m above ground while being directly connected to D-GPS (Leica GPS1200) for positioning. The acquisition rate was five measurements per second. Data quality was checked by measuring a reference line before and after each measurement. The area investigated by EMI in June 2023 is located to the north and northeast of the Gülpe research station. It has a total area of 12.3 ha. The reference line was located in the southern part of the study area. No drift correction had to be applied due to good data quality. Reference lines and single outliers were removed. The data set contains the EMI data with an intercoil spacing of 0.32 m.
Electromagnetic induction (EMI) was measured with a CMD-Mini Explorer (GF Instruments s.r.o., Brno, Czech Republic) in May 2018 and June 2019. We used the vertical dipole (VDP) at coil spacings of 0.32 m (VDP1), 0.71 m (VDP2) and 1.18 m (VDP3). With the existing coil spacings, effective penetration depths of 0.5 m (VDP1), 1.0 m (VDP2) and 1.8 m (VDP3) could be achieved. According to the manufacturer, 70 % of the signal originate from above these depths. The EMI sensors measured the apparent electrical conductivity (ECa, in mS/m). Measurements were taken by carrying the instrument about 0.2 m above the ground while being directly connected to D-GPS (Leica GPS1200) for positioning. The acquisition rate was five measurements per second. Data quality was checked by measuring a reference line before and after each measurement. The maximum offset of the EMI values between the two time points was 1.5 mS/m. We corrected the data and removed the reference lines and single outliers. The data set contains the EMI data with an intercoil spacing of 0.71 m (VDP2).
The dataset was used to explore the spatial distribution of fluvial deposits in the area of the Ahr valley floor southwest of Mayschoß. The objective of this investigation was to extrapolate the findings of a chronological classification of an embedded floodplain cross-section, thereby underscoring the significance of fluvial geomorphological records in reconstructing past high-magnitude flood events. In detail, we used geophysical prospection methods (Electromagnetic Induction and Electrical Resistivity Tomography) to map the distribution and thickness of floodplain sediments as both methods provide proxy information on grain size distribution. Electromagnetic induction (EMI) was measured with a CMD-Mini Explorer and a CMD Explorer (both GF Instruments s.r.o., Brno, Czech Republic) in June 2022. We used the vertical dipole (VDP) at coil spacings of 0.32 m (VDP1, CMD Mini Explorer), 0.71 m (VDP2, CMD Mini Explorer), 1.18 m (VDP3, CMD Mini Explorer), 1.48 m (VDP4, CMD Explorer), 2.82 m (VDP5, CMD Explorer) and 4.49 m (VDP6, CMD Explorer). With the existing coil spacings, effective penetration depths of 0.5 m (VDP1), 1.0 m (VDP2) and 1.8 m (VDP3) for the CMD Mini Explorer and 2.2 m (VDP4), 4.2 m (VDP5) and 6.7 m (VDP6) for the CMD Explorer could be achieved. According to the manufacturer, 70 % of the signal originate from above these depths. The EMI sensors measured the apparent electrical conductivity (ECa, in mS/m). Measurements were taken by carrying the instrument about 0.2 m (CMD Mini Explorer) respectively 0.9 m (CMD Explorer) above the ground while being directly connected to Differential -GPS (Leica GPS1200) for positioning. The acquisition rate was five measurements per second. Data quality was checked by measuring a reference line before and after each measurement. The maximum offset of the EMI values between the two time points was 1.2 mS/m. A correction of the data was not necessary. We removed the reference lines and single outliers. In addition, two interference areas were removed from all EMI data sets. (1) a L-shapped area, running from north to the center and then to east, in which an underground power cable runs. (2) an area on the north-eastern part of the measurement area. Information on the location and extent of the removed interference areas can be found in the enclosed explanation of the EMI measurements. The Electrical Resistivity Tomography (ERT) data were acquired by using a PC controlled DC resistivity meter system (RESECS, GeoServe, Kiel, Germany) in October 2022. We measured a total of four transects with an electrode spacing 1 m. Transect 1 has a total length of 255 m, transect 2 a total length of 207 m, transect 3 a total length of 136 m and transect 4 a total length of 158 m. For all transects we applied a Wenner alpha and Dipole-Dipole configuration. The coordinates and the height of the electrodes were measured with a Differential-GPS (Leica GPS1200). Further information on the measurement setup and data structure can be found in the explanation of the specific ERT transects.
Electromagnetic induction (EMI) was measured with a CMD-Mini Explorer and a CMD Explorer (both GF Instruments s.r.o., Brno, Czech Republic) in June 2022. We used the vertical dipole (VDP) at coil spacings of 0.32 m (VDP1, CMD Mini Explorer), 0.71 m (VDP2, CMD Mini Explorer), 1.18 m (VDP3, CMD Mini Explorer), 1.48 m (VDP4, CMD Explorer), 2.82 m (VDP5, CMD Explorer) and 4.49 m (VDP6, CMD Explorer). With the existing coil spacings, effective penetration depths of 0.5 m (VDP1), 1.0 m (VDP2) and 1.8 m (VDP3) for the CMD Mini Explorer and 2.2 m (VDP4), 4.2 m (VDP5) and 6.7 m (VDP6) for the CMD Explorer could be achieved. According to the manufacturer, 70 % of the signal originate from above these depths. The EMI sensors measured the apparent electrical conductivity (ECa, in mS/m). Measurements were taken by carrying the instrument about 0.2 m (CMD Mini Explorer) respectively 0.9 m (CMD Explorer) above the ground while being directly connected to Differential -GPS (Leica GPS1200) for positioning. The acquisition rate was five measurements per second. Data quality was checked by measuring a reference line before and after each measurement. The maximum offset of the EMI values between the two time points was 1.2 mS/m. A correction of the data was not necessary. We removed the reference lines and single outliers. In addition, two interference areas were removed from all EMI data sets. (1) a L-shapped area, running from north to the center and then to east, in which an underground power cable runs. (2) an area on the north-eastern part of the measurement area. Information on the location and extent of the removed interference areas can be found in the enclosed explanation of the EMI measurements. The data set contains the EMI data with an intercoil spacing of 2.82 m (VDP5, CMD Explorer).
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