Advective transport in heterogeneous aquifers: Are proxy models predictive?
2015 (English)In: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 51, no 12, 9577-9594 p.Article in journal (Refereed) PublishedText
We examine the prediction capability of two approximate models (Multi-Rate Mass Transfer (MRMT) and Continuous Time Random Walk (CTRW)) of non-Fickian transport, by comparison with accurate 2-D and 3-D numerical simulations. Both nonlocal in time approaches circumvent the need to solve the flow and transport equations by using proxy models to advection, providing the breakthrough curves (BTC) at control planes at any x, depending on a vector of five unknown parameters. Although underlain by different mechanisms, the two models have an identical structure in the Laplace Transform domain and have the Markovian property of independent transitions. We show that also the numerical BTCs enjoy the Markovian property. Following the procedure recommended in the literature, along a practitioner perspective, we first calibrate the parameters values by a best fit with the numerical BTC at a control plane at x(1), close to the injection plane, and subsequently use it for prediction at further control planes for a few values of sigma(2)(gamma) <= 8. Due to a similar structure and Markovian property, the two methods perform equally well in matching the numerical BTC. The identified parameters are generally not unique, making their identification somewhat arbitrary. The inverse Gaussian model and the recently developed Multi-Indicator Model (MIM), which does not require any fitting as it relates the BTC to the permeability structure, are also discussed. The application of the proxy models for prediction requires carrying out transport field tests of large plumes for a long duration.
Place, publisher, year, edition, pages
American Geophysical Union (AGU), 2015. Vol. 51, no 12, 9577-9594 p.
IdentifiersURN: urn:nbn:se:kth:diva-182180DOI: 10.1002/2015WR017118ISI: 000368421500010ScopusID: 2-s2.0-84958729627OAI: oai:DiVA.org:kth-182180DiVA: diva2:903754
QC 201602162016-02-162016-02-162016-02-16Bibliographically approved