1,721,043 research outputs found
Groundwater flow patterns in a coastal fen exposed to drainage, rewetting and interaction with the Baltic Sea
No full texthttp://dx.doi.org/10.13039/501100001659 Deutsche Forschungsgemeinschaf
Redox changes during alternating saturated and unsaturated conditions below an artificial recharge pond
No full textModeling seasonal redox dynamics and the corresponding fate of the pharmaceutical residue phenazone during artificial recharge of groundwater
No full textReactive multicomponent transport modeling was used to investigate and quantify the factors that affect redox zonation and the fate of the pharmaceutical residue phenazone during artificial recharge of groundwater at an infiltration site in Berlin, Germany. The calibrated model and the corresponding sensitivity analysis demonstrated that temporal and spatial redox zonation at the study site was driven by seasonally changing, temperature-dependent organic matter degradation rates. Breakthrough of phenazone at monitoring wells occurred primarily during the warmer summer months, when anaerobic conditions developed. Assuming a redox-sensitive phenazone degradation behavior the model results provided an excellent agreement between simulated and measured phenazone concentrations. Therefore, the fate of phenazone was shown to be indirectly controlled by the infiltration water temperature through its effect on the aquifer's redox conditions. Other factors such as variable residence times appeared to be of less importance
Redox changes during alternating saturated and unsaturated conditions below an artificial recharge pond
No full textModelling the removal of p-TSA (para-toluenesulfonamide) during rapid sand filtration used for drinking water treatment
No full textA finite element model was set-up to determine degradation rate constants for p-TSA during rapid sand filtration (RSF). Data used for the model originated from a column experiment carried out in the filter hall of a drinking water treatment plant in Berlin (Germany). Aerated abstracted groundwater was passed through a 1.6 m long column-shaped experimental sand filter applying infiltration rates from 2 to 6 in h(-1). Model results were fitted to measured profiles and breakthrough curves of p-TSA for different infiltration rates using both first-order reaction kinetics and Michaelis-Menten kinetics. Both approaches showed that degradation rates varied both in space and time. Higher degradation rates were observed in the upper part of the column, probably related to higher microbial activity in this zone. Measured and simulated breakthrough curves revealed an adaption phase with lower degradation rates after infiltration rates were changed, followed by an adapted phase with more elevated degradation rates. Irrespective of the mathematical approach and the infiltration rate, degradation rates were very high, probably owing to the fact that filter sands have been in operation for decades, receiving high p-TSA concentrations with the raw water. (C) 2009 Elsevier Ltd. All rights reserved
Workflow, Scripts, and Data for paper "Phase-Averaged Tidal Boundary Condition for Transient, Regional-Scale Tidal Overheight in Numerical Groundwater Flow Models"
No full textData, scripts, and workflow for the manuscript
Haehnel, P., Greskowiak, J., and Massmann, G. (2022). Phase-Averaged Tidal Boundary Condition for Transient, Regional-Scale Tidal Overheight in Numerical Groundwater Flow Models. Water Resources Research (submitted).
This record provides the complete procedure of data preparation, model simulation, simulation post-processing, and analysis performed to obtain the results presented in the aforementioned publication.
A Python module 'mfpatbc', which provides a flopy comaptible implementation of the phase-averaged tidal boundary condition presented in the publication, is available at https://github.com/phaehnel/mfpatbc [made public if manuscript is accepted].
Brief summary of the record contents
figures.zip contains figures as present in the publication and corresponding scripts used to create them.
ICAM.zip contains workflow, data, scripts, and results of the paramater study on an idealized coastal aquifer model (ICAM). The ICAM is a cross-sectional model of a simple coastal aquifer, implemented in MODFLOW-NWT. The empirical correction function for the phase-averaged tidal boundary condition presented in the associated paper is derived from the simulation results of the parameter study.
LICENSE.txt contains license information for this record as well as all data and software from external sources which was required in the workflow and is provided in this record. References to the metadata of data and software from external sources are provided in 'Related identifiers'.
prepare_tide_data.zip contains tide gauge data from Wangerooge West, scripts and workflow to prepare them for further usage in the groundwater flow model of Spiekeroog.
SPK[X].zip contain workflow, data, scripts, and results for the real-world application of the developed phase-averaged tidal boundary condition. This is a transient, three-dimensional, and unconfined numerical groundwater flow model of the barrier island of Spiekeroog (Northern Germany), implemented in MODFLOW-2005. Is split up into multiple zip-files for size reasons.
tables.zip contains tables and data sets as present in the publication and corresponding scripts used to create them.
videos.zip contains movies present in the publications' supporting information and corresponding scripts used to create them.
zipsplit.idx lists the directory of all files within the folder 'SPK' files in the split zip-files 'SPK[X].zip'.
Folders 'ICAM', 'SPK', and 'prepare_tide_data' contain DOCUMENTATION.txt files that guide through the structure of the folder and shortly describe the contents. Metadata on data files is provided within these folders as well. Such files are named 'META_DATA.txt'. The zip-folders resemble the first level of the folder structure of the workflow. Make sure to merge the folders 'SPK[X].zip' as described below.
Required software
Scripts are written in Python (Version 3.7.7) and R (Version 4.1.2). Some geospatial tasks were performed with QGIS (Version 3.20.1). Groundwater flow simulations were performed with MODFLOW-NWT (Version 1.2.0) and MODFLOW-2005 (Version 1.12.0) with flopy (Version 3.3.3). MODFLOW binary executables compiled on a Ubuntu 20.04 system are included in this record. Should you require other ones, consider https://github.com/MODFLOW-USGS/executables or https://github.com/modflowpy/pymake.
Merging zip-files for folder 'SPK'
The folder containing the workflow of the Spiekeroog model was split into multiple zip-files. They are named 'SPK[X].zip' where [X] = 1, 2, 3, … . On Windows, you may merge them into the original folder by extracting all the zip-files 'SPK[X].zip' into the same folder. Make sure that this folder is named 'SPK', otherwise certain scripts may not work.
On Linux, you may use the terminal and something like
cat SPK*.zip > SPK.zip
unzip SPK.zip
or do it manually as described for Windows.Project funding was provided by the Federal Ministry of Education and Research of Germany (BMBF project WAKOS, funding reference number 01LR2003E)
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Dynamic bioreactor hyporheic zone - CO2 production and attenuation of trace organic compounds in streambeds
No full textDie hyporheische Zone (HZ) ist ein zentraler Bestandteil von Flussökosystemen und spielt eine entscheidende Rolle für die Wasserqualität. Sie bezeichnet den Bereich im Flussbett, der alle Porenwasserfließpfade umfasst, die an der Sedimentoberfläche beginnen und enden. Die HZ fungiert als „Bioreaktor“, der organischen Kohlenstoff umwandelt und organische Spurenstoffe (TrOCs) abbaut. Ziel der vorliegenden Dissertation ist es, den Einfluss dynamischer Faktoren auf die HZ besser zu verstehen. Untersucht wird, wie Flussregime die Bewegung des Flusssediments, den hyporheischen Austausch und biogeochemische Prozesse beeinflussen. Darüber hinaus werden der Einfluss der saisonalen Variabilität sowie die Zusammensetzung gelöster organischer Substanzen auf den Abbau von TrOCs betrachtet. Diese Ziele wurden in fünf Studien behandelt. Die Ergebnisse zeigen, dass die Fortbewegung von Bettformen einen tiefgreifenden Einfluss auf den hyporheischen Austausch, die Verteilung von O₂ und CO₂ sowie auf die Atmungsraten in Flussbetten hat. Bereits sehr langsame Bewegungen führen zu deutlich höheren Atmungsraten im Vergleich zu unbewegten Sedimenten. Obwohl für dynamische Abflussregime insgesamt höhere Atmungsraten erwartet wurden, reduzieren die deutlich niedrigeren Raten in den unbewegten Phasen die insgesamt verbrauchte O₂- und produzierte CO₂-Menge. Angesichts des starken Einflusses der Bewegung von Sedimentstrukturen auf die Atmungsraten sollte die zukünftige Forschung untersuchen, wie Abflussregime und Bettformbewegungen den Abbau von TrOCs beeinflussen. Die Dissertation zeigt, dass der Abbau von TrOCs überwiegend in der HZ stattfindet. Entgegen den Erwartungen wurden TrOCs im Winter besser abgebaut. Dies lässt sich durch längere Aufenthaltszeiten des Porenwassers im Flussbett infolge eines eingeschränkten hyporheischen Austauschs erklären. Längere Aufenthaltszeiten und ein lokaler starker Abbau im Flussbett führen jedoch nicht zwingend zu einem hohen Gesamtabbau im Flusssystem.The hyporheic zone (HZ) is a valuable component of stream ecosystems, playing a critical role in regulating streamwater quality through various processes. It is defined as the zone of the streambed containing all porewater flow paths that begin and end at the sediment-water interface. The HZ is a "bioreactor” that transforms organic carbon (C) and attenuates trace organic compounds (TrOCs). The aim of the present thesis is to better understand the influence of dynamic factors on HZs by understanding how flow regimes influence sediment migration, hyporheic exchange, and biogeochemical processes. Additionally, it investigates how seasonal variability and dissolved organic matter composition affect TrOC attenuation. These objectives were addressed through five research studies. The results demonstrate that bedform celerity profoundly affects hyporheic exchange, the distribution of O2 and CO2, and respiration rates in streambeds. Especially, even slow bedform movements result in markedly higher respiration rates compared to non-moving sediments, emphasizing the need to consider moving sediments in future studies. Although dynamic flow regimes were expected to show overall higher respiration rates, the much lower rates observed during the non-moving periods of dynamic flows reduced the total amount of O2 consumed and CO2 produced. Given the strong influence of moving bedforms on respiration rates, future research should investigate how flow regimes and bedform movement affect TrOC attenuation. This thesis showed that the attenuation of TrOCs occurred predominately in the HZ rather than in streamwater. Contrary to expectations, TrOCs were better attenuated in winter assumably due to higher residence times of porewater in the streambed. However, longer residence times and locally high attenuation in streambeds do not necessarily translate to high overall stream attenuation. A limited HZ would only contribute little to the total attenuation of TrOCs in stream systems
Supplimentary videos of the published article "Investigating the occurance of flow instabilities in coastal unconfined aquifers using sand tank experiments"
No full text- …
