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Koohbor B., Fahs M., Ataie-Ashtiani B., Belfort B., Simmons C. T., Younes Anis. (2019). Uncertainty analysis for seawater intrusion in fractured coastal aquifers : effects of fracture location, aperture, density and hydrodynamic parameters. Journal of Hydrology, 571, 159-177. ISSN 0022-1694

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Lien direct chez l'éditeur doi:10.1016/j.jhydrol.2019.01.052

Titre
Uncertainty analysis for seawater intrusion in fractured coastal aquifers : effects of fracture location, aperture, density and hydrodynamic parameters
Année de publication2019
Type de documentArticle référencé dans le Web of Science WOS:000462692100014
AuteursKoohbor B., Fahs M., Ataie-Ashtiani B., Belfort B., Simmons C. T., Younes Anis.
SourceJournal of Hydrology, 2019, 571, p. 159-177. ISSN 0022-1694
RésuméIn this study we use polynomial chaos expansion (PCE) to perform uncertainty analysis for seawater intrusion (SWI) in fractured coastal aquifers (FCAs) which is simulated using the coupled discrete fracture network (DFN) and variable-density flow (VDF) models. The DFN-VDF model requires detailed discontinuous analysis of the fractures. In real field applications, these characteristics are usually uncertain which may have a major effect on the predictive capability of the model. Thus, we perform global sensitivity analysis (GSA) to provide a preliminary assessment on how these uncertainties can affect the model outputs. As our conceptual model, we consider fractured configurations of the Henry Problem which is widely used to understand SWI processes. A finite element DFN-VDF model is developed in the framework of COMSOL Multiphysics (R). We examine the uncertainty of several SWI metrics and salinity distribution due to the incomplete knowledge of fracture characteristics. PCE is used as a surrogate model to reduce the computational burden. A new sparse PCE technique is used to allow for high polynomial orders at low computational cost. The Sobol' indices (SIs) are used as sensitivity measures to identify the key variables driving the model outputs uncertainties. The proposed GSA methodology based on PCE and SIs is useful for identifying the source of uncertainties on the model outputs with an affordable computational cost and an acceptable accuracy. It shows that fracture hydraulic conductivity is the first source of uncertainty on the salinity distribution. The imperfect knowledge of fracture location and density affects mainly the toe position and the total flux of saltwater entering the aquifer. Marginal effects based on the PCE are used to understand the effects of fracture characteristics on SWI. The findings provide a technical support for monitoring, controlling and preventing SWI in FCAs.
Plan de classementHydrologie [062] ; Sciences fondamentales / Techniques d'analyse et de recherche [020]
LocalisationFonds IRD [F B010075554]
Identifiant IRDfdi:010075554
Lien permanenthttp://www.documentation.ird.fr/hor/fdi:010075554

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