Evaluating the sensitivity of a subsurface multicomponent reactive transport model with respect to transport and reaction parameters

Caroline L. Tebes-Stevens, Felipe Espinoza, Albert J. Valocchi

Research output: Contribution to journalArticlepeer-review


The input variables for a numerical model of reactive solute transport in groundwater include both transport parameters, such as hydraulic conductivity and infiltration, and reaction parameters that describe the important chemical and biological processes in the system. These parameters are subject to uncertainty due to measurement error and due to the spatial variability of properties in the subsurface environment. This paper compares the relative effects of uncertainty in the transport and reaction parameters on the results of a solute transport model. This question is addressed by comparing the magnitudes of the local sensitivity coefficients for transport and reaction parameters. General sensitivity equations are presented for transport parameters, reaction parameters, and the initial (background) concentrations in the problem domain. Parameter sensitivity coefficients are then calculated for an example problem in which uranium(VI) hydrolysis species are transported through a two-dimensional domain with a spatially variable pattern of surface complexation sites. In this example, the reaction model includes equilibrium speciation reactions and mass transfer-limited non-electrostatic surface complexation reactions. The set of parameters to which the model is most sensitive includes the initial concentration of one of the surface sites, the formation constant (Kf) of one of the surface complexes and the hydraulic conductivity within the reactive zone. For this example problem, the sensitivity analysis demonstrates that transport and reaction parameters are equally important in terms of how their variability affects the model results.

Original languageEnglish (US)
Pages (from-to)3-27
Number of pages25
JournalJournal of Contaminant Hydrology
Issue number1-4
StatePublished - 2001


  • Contaminant transport
  • Groundwater
  • Hydraulic conductivity
  • Mathematical modeling
  • Sensitivity analysis
  • Sorption parameters

ASJC Scopus subject areas

  • Environmental Chemistry
  • Water Science and Technology


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