Analysis of tracer tomography using temporal moments of tracer breakthrough curves

Junfeng Zhu, Xing Cai, Tian Chyi Jim Yeh

Research output: Contribution to journalArticle

18 Scopus citations

Abstract

Hydraulic/partitioning tracer tomography (HPTT) was recently developed by Yeh and Zhu [Yeh T-CJ, Zhu J. Hydraulic/partitioning tracer tomography for characterization of dense nonaqueous phase liquid source zones, Water Resour Res 2007;43:W06435. doi:10.1029/2006WR004877.] for estimating spatial distribution of dense nonaqueous phase liquids (DNAPLs) in the subsurface. Since discrete tracer concentration data are directly utilized for the estimation of DNAPLs, this approach solves the hyperbolic convection-dispersion equation. Solution to the convection-dispersion equation however demands fine temporal and spatial discretization, resulting in high computational cost for an HPTT analysis. In this work, we use temporal moments of tracer breakthrough curves instead of discrete concentration data to estimate DNAPL distribution. This approach solves time independent partial differential equations of the temporal moments, and therefore avoids solving the convection-dispersion equation using a time marching scheme, resulting in a dramatic reduction of computational cost. To reduce numerical oscillations associated with convection dominated transport problems such as in inter-well tracer tests, the approach uses a finite element solver adopting the streamline upwind Petrov-Galerkin method to calculate moments and sensitivities. We test the temporal moment approach through numerical simulations. Comparing the computational costs between utilizing moments and discrete concentrations, we find that temporal moments significantly reduce the computation time. We also find that tracer moment data collected through a tomographic survey alone are able to yield reasonable estimates of hydraulic conductivity, as indicated by a correlation of 0.588 between estimated and true hydraulic conductivity fields in the synthetic case study.

Original languageEnglish (US)
Pages (from-to)391-400
Number of pages10
JournalAdvances in Water Resources
Volume32
Issue number3
DOIs
StatePublished - Mar 1 2009

Keywords

  • Hydraulic/tracer tomography
  • Parameter estimation
  • Source zone characterization
  • Temporal moments

ASJC Scopus subject areas

  • Water Science and Technology

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