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Field investigation into unsaturated flow and transport in a fault: Model analyses

Journal of Contaminant Hydrology

By:
, , , ,
DOI: 10.1016/j.jconhyd.2004.02.004

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Abstract

Results of a fault test performed in the unsaturated zone of Yucca Mountain, Nevada, were analyzed using a three-dimensional numerical model. The fault was explicitly represented as a discrete feature and the surrounding rock was treated as a dual-continuum (fracture-matrix) system. Model calibration against seepage and water-travel-velocity data suggests that lithophysal cavities connected to fractures can considerably enhance the effective fracture porosity and therefore retard water flow in fractures. Comparisons between simulation results and tracer concentration data also indicate that matrix diffusion is an important mechanism for solute transport in unsaturated fractured rock. We found that an increased fault-matrix and fracture-matrix interface areas were needed to match the observed tracer data, which is consistent with previous studies. The study results suggest that the current site-scale model for the unsaturated zone of Yucca Mountain may underestimate radionuclide transport time within the unsaturated zone, because an increased fracture-matrix interface area and the increased effective fracture porosity arising from lithophysal cavities are not considered in the current site-scale model. ?? 2004 Published by Elsevier B.V.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Field investigation into unsaturated flow and transport in a fault: Model analyses
Series title:
Journal of Contaminant Hydrology
DOI:
10.1016/j.jconhyd.2004.02.004
Volume
74
Issue:
1-4
Year Published:
2004
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
39
Last page:
59
Number of Pages:
21