%A Williams,Thomas %A Sanglas,Jordi %A Trinchero,Paolo %A Gai,Guanqun %A Painter,Scott L. %A Selroos,Jan-Olof %D 2021 %J Frontiers in Earth Science %C %F %G English %K groundwater modelling,Radionuclide transport,Discrete fracture network,DFN,upscaling,downscaling %Q %R 10.3389/feart.2020.586247 %W %L %M %P %7 %8 2021-February-02 %9 Original Research %# %! Recovering transport effects of heterogeneity %* %< %T Recovering the Effects of Subgrid Heterogeneity in Simulations of Radionuclide Transport Through Fractured Media %U https://www.frontiersin.org/articles/10.3389/feart.2020.586247 %V 8 %0 JOURNAL ARTICLE %@ 2296-6463 %X Groundwater flow and contaminant transport through fractured media can be simulated using Discrete Fracture Network (DFN) models which provide a natural description of structural heterogeneity. However, this approach is computationally expensive, with the large number of intersecting fractures necessitated by many real-world applications requiring modeling simplifications to be made for calculations to be tractable. Upscaling methods commonly used for this purpose can result in some loss of local-scale variability in the groundwater flow velocity field, resulting in underestimation of particle travel times, transport resistance and retention in transport calculations. In this paper, a transport downscaling algorithm to recover the transport effects of heterogeneity is tested on a synthetic Brittle Fault Zone model, motivated by the problem of large safety assessment calculations for geological repositories of spent nuclear fuel. We show that the variability in the local-scale velocity field which is lost by upscaling can be recovered by sampling from a library of DFN transport paths, accurately reproducing DFN transport statistic distributions and radionuclide breakthrough curves in an upscaled model.