Continuum-based DFN-consistent numerical framework for the simulation of oxygen infiltration into fractured crystalline rocks

We present an enhanced continuum-based approach for the modelling of groundwater flow coupled with reactive transport in crystalline fractured rocks. In the proposed formulation, flow, transport and geochemical parameters are represented onto a numerical grid using Discrete Fracture Network (DFN) de...

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Bibliographic Details
Published in:Journal of contaminant hydrology 2017-05, Vol.200, p.60-69
Main Authors: Trinchero, Paolo, Puigdomenech, Ignasi, Molinero, Jorge, Ebrahimi, Hedieh, Gylling, Björn, Svensson, Urban, Bosbach, Dirk, Deissmann, Guido
Format: Article
Language:English
Subjects:
DFN-derived parameters
Groundwater - chemistry
High performance reactive transport modelling
Hydrology - methods
Iron - chemistry
Minerals - chemistry
Models, Theoretical
Oxidation-Reduction
Oxygen - analysis
Oxygen - chemistry
Oxygen intrusion
Sweden
Water Movements
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Summary:We present an enhanced continuum-based approach for the modelling of groundwater flow coupled with reactive transport in crystalline fractured rocks. In the proposed formulation, flow, transport and geochemical parameters are represented onto a numerical grid using Discrete Fracture Network (DFN) derived parameters. The geochemical reactions are further constrained by field observations of mineral distribution. To illustrate how the approach can be used to include physical and geochemical complexities into reactive transport calculations, we have analysed the potential ingress of oxygenated glacial-meltwater in a heterogeneous fractured rock using the Forsmark site (Sweden) as an example. The results of high-performance reactive transport calculations show that, after a quick oxygen penetration, steady state conditions are attained where abiotic reactions (i.e. the dissolution of chlorite and the homogeneous oxidation of aqueous iron(II) ions) counterbalance advective oxygen fluxes. The results show that most of the chlorite becomes depleted in the highly conductive deformation zones where higher mineral surface areas are available for reactions. •A framework for reactive transport modelling in fractured media is presented.•Flow, transport and geochemical parameters are derived from an underlying DFN.•The infiltration of oxygenated water in a heterogeneous fractured medium is studied.•The results show that oxygen penetration is strongly controlled by the underlying DFN.•The results are compared with field evidence from Poços de Caldas (Brazil).
ISSN:0169-7722
1873-6009
DOI:10.1016/j.jconhyd.2017.04.001