Local and Global Sensitivity Analysis of a Reactive Transport Model Simulating Floodplain Redox Cycling
Abstract/Contents
- Abstract
- Reactive transport models (RTMs) are essential tools that simulate the coupling of advective, diffusive, and reactive processes in the subsurface, but their complexity makes them difficult to understand, develop and improve without accompanying statistical analyses. Although global sensitivity analysis (SA) can address these issues, the computational cost associated with most global SA techniques limits their use with RTMs. In this study, we apply distance-based generalized sensitivity analysis (DGSA), a novel and computationally efficient method of global SA, to a floodplain-scale RTM and compare DGSA results to those from local SA. Our test case focuses on the impact of 17 uncertain environmental parameters on spatially and temporally variable redox conditions within a floodplain aquifer. The input parameters considered include flow and diffusion rates, geochemical reaction rates, and the spatial distribution of sediment facies. Sensitivity was evaluated for three distinct components of the model response, encompassing both multidimensional and categorical output. Parameter rankings differ between local SA and DGSA, due to nonlinear effects of individual parameters and interaction effects between parameters. DGSA results show that fluid residence time, which is controlled by aquifer permeability, generally exerts a stronger control on redox conditions than do geochemical reaction rates. Sensitivity indices also demonstrate that sulfate reduction is key for establishing and maintaining reducing conditions throughout the aquifer. These results provide insights into the key drivers of heterogeneous redox processes within floodplain aquifers, as well as the main sources of uncertainty when modeling complex subsurface systems.
Description
| Type of resource | text |
|---|---|
| Publication date | November 9, 2022; November 9, 2021 |
Creators/Contributors
| Author | Perzan, Zach |
https://orcid.org/0000-0003-2676-2452
(unverified)
|
|---|---|---|
| Author | Babey, Tristan | |
| Author | Caers, Jef |
https://orcid.org/0000-0003-0262-9905
(unverified)
|
| Author | Bargar, John |
https://orcid.org/0000-0001-9303-4901
(unverified)
|
| Author | Maher, Kate |
https://orcid.org/0000-0002-5982-6064
(unverified)
|
Subjects
| Subject | Sensitivity theory (Mathematics) |
|---|---|
| Subject | Groundwater |
| Subject | Geochemistry |
| Subject | Geochemical modeling |
| Genre | Text |
| Genre | Article |
Bibliographic information
| Related item | |
|---|---|
| Location | https://purl.stanford.edu/tr920yf4428 |
Access conditions
- Use and reproduction
- User agrees that, where applicable, content will not be used to identify or to otherwise infringe the privacy or confidentiality rights of individuals. Content distributed via the Stanford Digital Repository may be subject to additional license and use restrictions applied by the depositor.
- License
- This work is licensed under a Creative Commons Attribution 4.0 International license (CC BY).
Preferred citation
- Preferred citation
- Perzan, Z., Babey, T., Caers, J., Bargar,J. R., & Maher, K. (2021). Local and global sensitivity analysis of a reactive transport model simulating floodplain redox cycling. Water Resources Research, 57, e2021WR029723. https://doi.org/10.1029/2021WR029723
Collection
Stanford University Open Access Articles
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- Contact
- zperzan@stanford.edu
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