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Title: Elements of complexity in subsurface modeling, exemplified with three case studies

Abstract

There are complexity elements to consider when applying subsurface flow and transport models to support environmental analyses. Modelers balance the benefits and costs of modeling along the spectrum of complexity, taking into account the attributes of more simple models (e.g., lower cost, faster execution, easier to explain, less mechanistic) and the attributes of more complex models (higher cost, slower execution, harder to explain, more mechanistic and technically defensible). In this paper, modeling complexity is examined with respect to considering this balance. The discussion of modeling complexity is organized into three primary elements: 1) modeling approach, 2) description of process, and 3) description of heterogeneity. Three examples are used to examine these complexity elements. Two of the examples use simulations generated from a complex model to develop simpler models for efficient use in model applications. The first example is designed to support performance evaluation of soil vapor extraction remediation in terms of groundwater protection. The second example investigates the importance of simulating different categories of geochemical reactions for carbon sequestration and selecting appropriate simplifications for use in evaluating sequestration scenarios. In the third example, the modeling history for a uranium-contaminated site demonstrates that conservative parameter estimates were inadequate surrogates for complex,more » critical processes and there is discussion on the selection of more appropriate model complexity for this application. All three examples highlight how complexity considerations are essential to create scientifically defensible models that achieve a balance between model simplification and complexity.« less

Authors:
 [1];  [1];  [1];  [1];  [1];  [1]
  1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE Office of Fossil Energy (FE)
OSTI Identifier:
1390420
Report Number(s):
PNNL-SA-128996
Journal ID: ISSN 1431-2174; 830403000
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Hydrogeology Journal
Additional Journal Information:
Journal Volume: 25; Journal Issue: 6; Journal ID: ISSN 1431-2174
Publisher:
Springer
Country of Publication:
United States
Language:
English
Subject:
numerical modeling; conceptual models; groundwater protection; heterogeneity solute transport

Citation Formats

Freedman, Vicky L., Truex, Michael J., Rockhold, Mark, Bacon, Diana H., Freshley, Mark D., and Wellman, Dawn M. Elements of complexity in subsurface modeling, exemplified with three case studies. United States: N. p., 2017. Web. doi:10.1007/s10040-017-1564-6.
Freedman, Vicky L., Truex, Michael J., Rockhold, Mark, Bacon, Diana H., Freshley, Mark D., & Wellman, Dawn M. Elements of complexity in subsurface modeling, exemplified with three case studies. United States. https://doi.org/10.1007/s10040-017-1564-6
Freedman, Vicky L., Truex, Michael J., Rockhold, Mark, Bacon, Diana H., Freshley, Mark D., and Wellman, Dawn M. 2017. "Elements of complexity in subsurface modeling, exemplified with three case studies". United States. https://doi.org/10.1007/s10040-017-1564-6.
@article{osti_1390420,
title = {Elements of complexity in subsurface modeling, exemplified with three case studies},
author = {Freedman, Vicky L. and Truex, Michael J. and Rockhold, Mark and Bacon, Diana H. and Freshley, Mark D. and Wellman, Dawn M.},
abstractNote = {There are complexity elements to consider when applying subsurface flow and transport models to support environmental analyses. Modelers balance the benefits and costs of modeling along the spectrum of complexity, taking into account the attributes of more simple models (e.g., lower cost, faster execution, easier to explain, less mechanistic) and the attributes of more complex models (higher cost, slower execution, harder to explain, more mechanistic and technically defensible). In this paper, modeling complexity is examined with respect to considering this balance. The discussion of modeling complexity is organized into three primary elements: 1) modeling approach, 2) description of process, and 3) description of heterogeneity. Three examples are used to examine these complexity elements. Two of the examples use simulations generated from a complex model to develop simpler models for efficient use in model applications. The first example is designed to support performance evaluation of soil vapor extraction remediation in terms of groundwater protection. The second example investigates the importance of simulating different categories of geochemical reactions for carbon sequestration and selecting appropriate simplifications for use in evaluating sequestration scenarios. In the third example, the modeling history for a uranium-contaminated site demonstrates that conservative parameter estimates were inadequate surrogates for complex, critical processes and there is discussion on the selection of more appropriate model complexity for this application. All three examples highlight how complexity considerations are essential to create scientifically defensible models that achieve a balance between model simplification and complexity.},
doi = {10.1007/s10040-017-1564-6},
url = {https://www.osti.gov/biblio/1390420}, journal = {Hydrogeology Journal},
issn = {1431-2174},
number = 6,
volume = 25,
place = {United States},
year = {Mon Apr 03 00:00:00 EDT 2017},
month = {Mon Apr 03 00:00:00 EDT 2017}
}

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