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Data and code repository for Experimental validation of graph-based modeling for coupled transport in fractured rocks


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Created: Jun 06, 2025 at 6:48 p.m. (UTC)
Last updated: Oct 15, 2026 at 7:39 p.m. (UTC) (Metadata update)
Published date: Oct 15, 2026 at 7:39 p.m. (UTC)
DOI: 10.4211/hs.b42bb8bcb54c4df3b1678557121a71c7
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Abstract

Fractures significantly influence flow and transport in subsurface geological systems. Coupled processes such as colloid transport, water-rock interactions, and fracture-matrix exchange complicate flow and transport modeling. Quantifying these coupled processes remains difficult due to the discrete and variable fracture geometry across rock lithologies and limitations of traditional experimental techniques. This study addresses these challenges by integrating pulse-tracer experiments, positron emission tomography (PET) imaging, and graph-based modeling to characterize colloid transport, radioactive decay, and fracture-matrix diffusion. Fluorodeoxyglucose (18F-FDG) was utilized as a radiotracer for flow-through experiments in fractured Niagaran dolomite, Berea sandstone, and Sierra granite cores under single-phase flow conditions. Radiolabeled 64Cu-kaolinite was then used for quantifying colloid transport in the fractured Sierra granite. PET imaging provided high-resolution, spatially resolved observations of tracer and colloid distributions within the cores at the millimeter scale. Experimental data were subsequently used to validate a discrete graph fracture network (DGFN) model that relies on a modified time domain random-walk (TDRW) particle tracking algorithm to incorporate matrix diffusion and first-order kinetics. Results demonstrate that the model is capable of accurately representing fracture-matrix interactions and first-order kinetics such as radioactive decay and irreversible colloid attachment. The approach efficiently captures complex transport phenomena without requiring a high-fidelity representation of fracture geometry, highlighting its potential as a computationally effective alternative to conventional simulation methods. While previous studies validated graph-based modeling for conservative solute transport, this study represents one of the first comparisons with observational data, highlighting the capability of representing coupled transport processes involving fracture-matrix exchanges, radioactive decay, and colloidal transport.

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README.md

Model and Figure Data — Experimental validation of graph-based modeling for coupled transport in fractured rocks

This archive contains the model outputs, experimental comparison data, source imaging data, and figure-generating notebooks associated with the manuscript [Experimental validation of graph-based modeling for coupled transport in fractured rocks]. It accompanies the open-source dgfn package, which implements the graph-based flow and transport modeling methods used here.

  • Software: dgfn (Discrete Graph Fracture Network), available on PyPI.
  • Install: pip install dgfn
  • Project page: https://pypi.org/project/dgfn/
  • Version used for this study: dgfn 0.1.0

What's in this archive

Figure and analysis notebooks

Notebook Purpose Requires dgfn?
DGFN_core_fits.ipynb The core-flood fitting workflow: builds graph networks for each rock core, calibrates apertures, runs TDRW transport, and fits modeled breakthrough curves (BTCs) to the experimental data. Produces the *_results.csv files. Yes
DGFN_method_figures.ipynb Generates the methodology / schematic figures illustrating the graph construction, flow solution, and transport algorithm. Yes
Paper_figures_of_model_data_comparison.ipynb Reads the result CSVs from the core fitting notebook and produces the exact experiment-vs-model comparison figures in the paper. Does not call dgfn directly — it operates on the precomputed result files so the user can avoid installing dgfn if desired. No

Model–experiment comparison data (breakthrough curves)

Each of these CSVs contains one experimental breakthrough curve and its fitted model, with the following columns:

Column Description
Time Time since injection start [seconds].
Inj_norm Normalized injected (inlet) concentration, C/C0 [-].
Prod_norm Normalized produced (outlet) concentration, C/C0 [-].
model Modeled outlet concentration from the dgfn TDRW fit, interpolated onto the experimental Time grid [-].
File Experiment
granite_point5ml_exp_model_results.csv Granite fracture, 0.5 mL/min, conservative tracer.
granite_1ml_exp_model_results.csv Granite fracture, 1.0 mL/min, conservative tracer.
granite_kao_exp_model_results.csv Granite fracture with kaolinite colloids, 0.5 mL/min.
dolomite_exp_model_results.csv Dolomite core, conservative tracer.
dolomite_exp_model_w_decay_results.csv Dolomite core including first-order (18F) decay.
berea_exp_model_results.csv Berea sandstone core, conservative tracer.
berea_exp_model_w_decay_results.csv Berea sandstone core including first-order (18F) decay.

These files are produced with the DGFN_core_fits.ipynb notebook.

Particle deposition data

File Description
granite_kao_deposition.csv Spatial map of kaolinite colloid deposition locations from the granite-kaolinite simulation. Columns: time [s], x, y, z [m] — the time and 3-D coordinate at which each deposited particle was filtered out of the flow field. Used to generate the deposition-map figure.

Source imaging data

File Description
22Nov2022_90min_90frames_60s_1mL_loop_graniteKaolinite2_64Cu_68_44_159_90_32b.raw Raw 4-D PET imaging dataset (64Cu tracer) of the granite-kaolinite core flood from which the granite graph network was derived. Dimensions encoded in the filename: 68 x 44 x 159 voxels x 90 time frames, 32-bit; 90 min acquisition, 60 s/frame, 1 mL injection loop. This is a headerless binary; see "Reading the .raw file" below.

How to reproduce the figures

  1. Install the model code and dependencies. Python 3.9+ recommended.

bash pip install dgfn cmcrameri jupyter

dgfn pulls in its own dependencies (numpy, scipy, pandas, networkx, matplotlib, scikit-learn). cmcrameri provides the scientific colormaps used in the figure notebooks, and jupyter is needed to run them.

  1. To regenerate the comparison figures only (fastest path — uses the precomputed result CSVs, no modeling required): launch Jupyter and run Paper_figures_of_model_data_comparison.ipynb. It reads the *_results.csv files in this archive.

  2. To re-run the full modeling workflow (rebuilds the fits from scratch): run DGFN_core_fits.ipynb. Note that this notebook requires the files in the core_breakthrough_curve_data folder (the experimental tracer CSVs with raw rad2/rad3 columns) and the graph_node_data_cores.xlsx graph-definition spreadsheet.

  3. To regenerate the method/schematic figures: (requires dgfn install) run DGFN_method_figures.ipynb.


Citation

If you use these data or the dgfn software, please cite Sutton, Duvvuri, and Zahasky (2026) Experimental validation of graph-based modeling for coupled transport in fractured rocks in Water Resources Research.


Credits

Funding Agencies

This resource was created using funding from the following sources:
Agency Name Award Title Award Number
National Science Foundation None EAR 2437912
American Chemical Society None 66040-DNI9
National Science Foundation None 2002412
Geological Society of America Graduate Student Research Grant None

Contributors

People or Organizations that contributed technically, materially, financially, or provided general support for the creation of the resource's content but are not considered authors.

Name Organization Address Phone Author Identifiers
Christopher Zahasky UW-Madison Department of Geoscience Wisconsin, US

How to Cite

Sutton, C. (2026). Data and code repository for Experimental validation of graph-based modeling for coupled transport in fractured rocks, HydroShare, https://doi.org/10.4211/hs.b42bb8bcb54c4df3b1678557121a71c7

This resource is shared under the Creative Commons Attribution CC BY.

http://creativecommons.org/licenses/by/4.0/
CC-BY

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