Document Detail


Incorporating layer- and local-scale heterogeneities in numerical simulation of unsaturated flow and tracer transport.
MedLine Citation:
PMID:  19042055     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
This study characterizes layer- and local-scale heterogeneities in hydraulic parameters (i.e., matrix permeability and porosity) and investigates the relative effect of layer- and local-scale heterogeneities on the uncertainty assessment of unsaturated flow and tracer transport in the unsaturated zone of Yucca Mountain, USA. The layer-scale heterogeneity is specific to hydrogeologic layers with layerwise properties, while the local-scale heterogeneity refers to the spatial variation of hydraulic properties within a layer. A Monte Carlo method is used to estimate mean, variance, and 5th, and 95th percentiles for the quantities of interest (e.g., matrix saturation and normalized cumulative mass arrival). Model simulations of unsaturated flow are evaluated by comparing the simulated and observed matrix saturations. Local-scale heterogeneity is examined by comparing the results of this study with those of the previous study that only considers layer-scale heterogeneity. We find that local-scale heterogeneity significantly increases predictive uncertainty in the percolation fluxes and tracer plumes, whereas the mean predictions are only slightly affected by the local-scale heterogeneity. The mean travel time of the conservative and reactive tracers to the water table in the early stage increases significantly due to the local-scale heterogeneity, while the influence of local-scale heterogeneity on travel time gradually decreases over time. Layer-scale heterogeneity is more important than local-scale heterogeneity for simulating overall tracer travel time, suggesting that it would be more cost-effective to reduce the layer-scale parameter uncertainty in order to reduce predictive uncertainty in tracer transport.
Authors:
Feng Pan; Ming Ye; Jianting Zhu; Yu-Shu Wu; Bill X Hu; Zhongbo Yu
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.     Date:  2008-11-05
Journal Detail:
Title:  Journal of contaminant hydrology     Volume:  103     ISSN:  0169-7722     ISO Abbreviation:  J. Contam. Hydrol.     Publication Date:  2009 Jan 
Date Detail:
Created Date:  2009-01-12     Completed Date:  2009-05-29     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8805644     Medline TA:  J Contam Hydrol     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  194-205     Citation Subset:  IM    
Affiliation:
Division of Hydrologic Sciences, Desert Research Institute, Nevada System of Higher Education, Las Vegas, NV 89119, United States.
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MeSH Terms
Descriptor/Qualifier:
Computer Simulation
Monte Carlo Method
Nevada
Time Factors
Uncertainty
Water Movements*

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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