Numerical modeling of water dynamics in Railway embankments

Description

This dataset contains input parameters for numerical modeling using HYDRUS to simulate water flow under railway embankments. It was generated to investigate water flow dynamics and distribution in railway embankments, with implications for the transport of herbicides affecting tracks and underlying structures. Numerical experiments using a univariate approach assessed how embankment and site-specific factors influence water content and flow patterns. Key parameters included hydraulic properties (saturated/residual water content, Van Genuchten parameters, and hydraulic conductivity), recharge rate, groundwater level, horizontal impermeable layers, and embankment thickness. The data for the reference model was based on drilling information from the funder and the hydraulic parameters estimated with the help of ROSETTA (Hydrus tool). The results were later visualized and post-processed in ParaView by importing the VTK files from Hydrus. Analysis of percolation fronts and flow paths identified groundwater levels and the Van Genuchten parameter (α) as the most influential factors. The simulations mimicked soil with and without moisture conditions (i.e. 30 days of average recharge rates in Germany). All the folders contain the input files for each scenario for the soil moisture conditions. To run the simulations without soil moisture conditions, exchange the file Atmosph.in for the file in the folder amts_dry. Brief description of the following parameters that were inspected (values of the parameters are written on the file name): 1. α (Van Genuchten Shape Parameter) - (1/m) controls the air entry value of the soil-water retention curve. 2. 𝑛 (Van Genuchten Pore-Size Distribution Parameter) - (dimensionless) defines the pore-size distribution's impact on the soil-water retention curve. 3. IMP - lower permeable Layer refers to a less permeable horizontal layer introduced at multiple depths (m) in the simulation domain. 4. GW - Groundwater Levels (m) indicates the depth or position of the groundwater table relative to the embankment structure. 5. qs - The saturated water content (dimensionless) represents the maximum volumetric water content of the soil, corresponding to full saturation. 6. qr - The residual water content (dimensionless) indicates the volumetric water content below which water movement ceases due to adhesion forces. 7. Kf - Saturated hydraulic conductivity (m/s) measures the soil's ability to transmit water under fully saturated conditions. 8. EMB - Embankment Thickness (m) defines the height or vertical extent of the embankment structure. It directly influences the overall storage capacity and the flow path lengths within the embankment, affecting water content distribution and hydraulic response.

Steps to reproduce

The models were run in a batch, using input files in the .in format, and setting up a batch process. Following the next steps: 1. Prepare the .in Files The .in files in Hydrus contain key input parameters such as Soil properties (e.g., Selector.in, Soil.in). 2. Setting Up Batch Files A batch file (.bat) allows you to automate running Hydrus for multiple configurations or input files without manual intervention. Writing the Batch File: Locate the Hydrus executable (e.g., H1D_CALC.EXE for Hydrus-2D). Usually found in the installation folder (e.g., C:\Hydrus-2D\). Create a .bat file to run simulations. 3. Modify the .in Files for Batch Simulations If running multiple configurations: Copy the original set of .in files to new directories for each simulation. Update specific parameters in the .in files as needed. The results were visualized using matplotlib and ParaView. To post-process Hydrus simulation data in ParaView, start by exporting the required output data from Hydrus, such as concentration or water content profiles, typically as CSV or VTK files. Open ParaView and load your file using the "Open" button. If the data is in tabular format, use the "Table to Points" filter to visualize the spatial distribution of data points. For 3D data, load the VTK file directly. Apply filters such as "Contour" to visualize isosurfaces, "Slice" to examine cross-sections, or "Volume Rendering" for 3D representations. Adjust color mapping to represent your variable of interest (e.g., concentration or saturation) and customize legends for better clarity. Use the "Animation View" to explore temporal changes if time steps are included, and export images or animations for reporting.

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