Impact of velocity correlation and distribution on transport in fractured media: Field evidence and theoretical model

TitleImpact of velocity correlation and distribution on transport in fractured media: Field evidence and theoretical model
Publication TypeJournal Article
Year of Publication2015
AuthorsKang, PK, Le Borgne, T, Dentz, M, Bour, O, Jung, N-H
JournalWater Resources Research
Volume51
Issue2
Pagination940 - 959
Date PublishedJan-02-2015
AbstractFlow and transport through fractured geologic media often leads to anomalous (non-Fickian)transport behavior, the origin of which remains a matter of debate: whether it arises from variability in frac-ture permeability (velocity distribution), connectedness in the flow paths through fractures (velocity correla-tion), or interaction between fractures and matrix. Here we show that this uncertainty of distribution- versuscorrelation-controlled transport can be resolved by combining convergent and push-pull tracer testsbecause flow reversibility is strongly dependent on velocity correlation, whereas late-time scaling of break-through curves is mainly controlled by velocity distribution. We build on this insight, and propose a Lagran-gian statistical model that takes the form of a continuous time random walk (CTRW) with correlated particlevelocities. In this framework, velocity distribution and velocity correlation are quantified by a Markov pro-cess of particle transition times that is characterized by a distribution function and a transition probability.Our transport model accurately captures the anomalous behavior in the breakthrough curves for bothpush-pull and convergent flow geometries, with the same set of parameters. Thus, the proposed correlatedCTRW modeling approach provides a simple yet powerful framework for characterizing the impact of veloc-ity distribution and correlation on transport in fractured media.
URLhttp://doi.wiley.com/10.1002/2014WR015799
DOI10.1002/2014WR015799
Short TitleWater Resour. Res.

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