3 results
Now showing1 - 3 of 3
- Some of the metrics are blocked by yourconsent settings
Item type:Research Data, Access status: with files , Erosion experiments with homogenized cohesive sediment samples from the Port of Hamburg - Erosion rates and erosion thresholds(2025-02-10); ; ; The data set was collected within the context of the research project ELMOD - “Simulation and analysis of the hydrological and morphological development of the Tidal Elbe for the period from 2013 to 2018”. In total, 34 erosion experiments have been conducted with homogenized cohesive sediment samples collected at two sites in the Port of Hamburg. The samples have been diluted to specific densities between 1050 - 1250 kg/m³ for the experiments. During the erosion experiments, a maximum of 13 loadsteps with a duration of 15 minutes each and bed shear stresses between 0.03 - 0.40 N/m² has been applied. The experimental procedure and the utilized erosion device (C-GEMS) are describe in detail in Witt et al, 2024 (https://doi.org/10.3389/fmars.2024.1386081). The data set consists of: 1. The (raw) experimental data collected in 34 erosion experiments with cohesive sediment samples from two locations in the Port of Hamburg (Norderelbe (NE) and Suederelbe (SE), see Witt et al, 2024). 2. The erosion thresholds (TauC) derived from the experimental data, following the methodology presented in Witt et al, 2024 (SSC-method). 3. The Python-Code used to derive the erosion thresholds from the raw data. 4. The grain size distribution (GSD) of the sediment samples from location NE and SE. 5. Visualizations of i) exemplary evolutions of the suspended sediment concentration (SSC) and erosion rates (ER) measured in selected experiments and ii) the derived erosion thresholds vs. the bulk density of the sediment samples for all experiments. Additional information: To 1: The files Experiments_raw_(NE).csv and Experiments_raw_(SE).csv contain the raw SSC-data of the experiments. During the experiments with the C-GEMS, the SSC was recorded in a frequency of 0.2 Hz by a Hach Solitax sc probe. The background SSC (measured before the start of each experiment) has already been substracted from the values included in the files, thus the values describe the increase in SSC in relation to the beginning of the experiments. Column "Time [s]" is the experimental duration, "Tau [N/m²]" is the nominal applied bed shear stress (*,more information below) and e.g. column "NE1-2_3-1100" contains the SSC-data (in mg/l) for one experiment with sediment from site NE and a homogeneous density of 1100 kg/m³. The term NE1-2_3 describes the exact sediment sample used for all experiments from site NE (the same applies for SE accordingly). The number in brackets following the described nomenclature, describes the number of the repetition experiment. For sediments from site SE densities from 1050 kg/m³ to 1200 kg/m³ and for sediments from site NE densities from 1100 kg/m³ to 1250 kg/m³ have been tested. The intervall between the tested desities was 25 kg/m³ each. For each tested density at least two repetitions have been conducted. For single experiments with sediment from site NE more repetitions have been carried out (up to 7). The water used for the experiments was site specific water collected in the Elbe. More information in Witt et al, 2024. *Two setups of the C-GEMS were used. For setup 2 the nominal applied bed shear stress has to be multiplied by the factor of 1.22. This applies to all experiments with repitition number "(2)" and additionally experiments NE1-2_3-1150 (4) and NE1-2_3-1150 (6). The relationship described above has already been taken into account in the further analyses and provided python-code. To 2: The files TauC_(NE).csv and TauC_(SE).csv contain the erosion threshold for each experiment derived by applying the SSC-method presented in Witt et al, 2024. Column "Density [kg/m³]" describes the density of the tested sample, column "TauC [N/m²]" the derived erosion threshold and "R^2" the coefficient of determination derived from the log-log regression of loadstep averaged SSC (see Witt et al, 2024). To 3: The files Calculation_TauC_SSC_(NE).py and Calculation_TauC_SSC_(SE).py contain the python-code, which was used for post-processing of the raw-data and calculation of the erosion thresholds. Python version 3.12.3 was used. The files need to be executed in the same folder as the respective raw-data file (or the path has to be adjusted in the code accordingly). If needed (e.g. for visualization), also files with moving-averages (60s) of the measured SSC and ER or load-step averaged values for SSC and ER can be written to separate files. To do so, the resp. lines in the code need to be un-commented. To 4: Files GSD_NE.txt and GSD_SE.txt contain information on the grain size distribution of the sediment samples from sites NE and SE. The GSD were derived by a combined hydrometer and sieve analysis. To 5: File Examples_SSC_ER_evolutions_(SE+NE).jpeg gives an impression of the results of the erosion experiments in terms of the SSC and ER evolutions for selected experiments with samples from both NE and SE site. File Visualization_Erosion_Threshold_(SE+NE).png visualizes the derived erosion thresholds for experiments with samples from both sites.Data Type: Experimental Data44 123 - Some of the metrics are blocked by yourconsent settings
Item type:Research Data, Access status: with files , Time-dependent density profiles of cohesive sediment samples from the Port of Hamburg(2024-08-26); ; ; The data set was collected within the context of the research project ELMOD - “Simulation and analysis of the hydrological and morphological development of the Tidal Elbe for the period from 2013 to 2018”. The aim was to: i) obtain information on the settling and consolidation behavior of the site-specific coehsive sediment and ii) create a data set for the calibration of numerical models. The dataset consists of time-dependent density profiles of six cohesive sediment samples, collected in the Elbe estuary in the area of the Port of Hamburg. The sediment of three samples each was collected on the "Suederelbe" (SE) and the "Norderelbe" (NE). The exact sampling positions are shown in Figure 1 in the following related publication: https://doi.org/10.3389/fmars.2024.1386081. The grain size distributions (GSD) of the sediment samples are included in the dataset. The sediment samples were diluted in the laboratory to densities between 1035 kg/m³ and 1080 kg/m³. The samples were thoroughly homogenized in a 20 cm diameter settling column, by mixing the suspension for 10 minutes with a stirring machine. After 15 minutes of settling the first density profile was taken. For this purpose, a small amount of suspension (~5 ml) was extracted from defined heights in the settling column (every 5 cm). This procedure was performed by inserting thin alloy tubes from the top of the suspension and aspirating the suspension with a syringe from the desired depth. Since this procedure disturbs the sediment sample/suspension above the extraction depth, the subsamples are taken from top to bottom. The densities of the subsamples are measured using an Anton Paar DMA 35 density meter. After the density measurement the subsamples are returned to the settling column. Since the whole sample is disturbed after a complete density profile has been taken, the sample is homogenized again using the same procedure (10 minutes stirring) and the next profile can be taken after e.g. 30 minutes of settling. The described procedure was first presented in https://doi.org/10.3389/feart.2022.916056. In order to improve the data quality, slight modifications of the procedure have been introduced for the collection and evaluation of the presented data set: From the suspension/water surface to the lutocline, the density is set to the measured water density, since the variations in this area are < 1 g/l. To capture the area of the lutocline, where the largest gradients of the density profiles occur, the first subsample was taken 1 cm below the lutocline for each profile. Subsequent subsamples were taken at the fixed depths, 5 cm apart. For the updated version of the dataset, the profiles for 24h settling time for NE-sediment with initial densities of 1050 kg/m³ and 1065 kg/m³ have been repeated and corrected. The results of the previous version suggested irregularities in the recording of these two single profiles, since the integration of the measured densities over the settling column height showed an unusual deviation, compared to the other profiles of the same density. To test the repeatability of the results, the measurement of the 24h profile of sample NE1-8 with an initial density of ~1042 kg/m³ was repeated five times (sample homogenized and allowed to settle for 24h each time). The file NE1-8_1042_24h_Repetitions_DensityProfiles.csv contains the single density profiles of the five repetitions. Examplary explanation of the nomenclature of the files: GSD_NE1-8.txt -> Grain size distribution data for sample NE1-8 (NE1-8 indicates the eighth sample taken during campaign NE1) NE1-8_1035_DensityProfiles.csv -> Time-dependent density profiles of sample NE1-8 with an initial density of 1035 kg/m³. The initial height of the suspension is given in the .csv file (70-80 cm). NE1-8_1042_24h_Repetitions_DensityProfiles.csv -> Repetitions of the density profile of sample NE1-8 with an initial density of ~1042 kg/m³ after 24 hours of settling/consolidation.Data Type: Experimental Data39 90 - Some of the metrics are blocked by yourconsent settings
Item type:Research Data, Access status: with files , Lab prepared sediment samples from the weser estuary - density profiles, settling & grain size curve(2021-03-05); ; In 2019, sediment cores were taken from the Weser estuary at Weser-Km 63,5 (Blexer Bogen) during slackwater and subsequently processed in the laboratory for settling and sedimentation studies. Density profiles were established on these laboratory-prepared samples (homogene initial concentration) according to defined time intervals. This allows the assessment of the temporal density development and supports the optimization of numerical consolidation models. The data set is supplemented by a grading curve of the sediment at the beginning of the experiment.Data Type: Dataset236 177