Document Detail

Estimation of local scale dispersion from local breakthrough curves during a tracer test in a heterogeneous aquifer: the Lagrangian approach.
MedLine Citation:
PMID:  11848265     Owner:  NLM     Status:  MEDLINE    
The local scale dispersion tensor, Dd, is a controlling parameter for the dilution of concentrations in a solute plume that is displaced by groundwater flow in a heterogeneous aquifer. In this paper, we estimate the local scale dispersion from time series or breakthrough curves, BTCs, of Br concentrations that were measured at several points in a fluvial aquifer during a natural gradient tracer test at Krauthausen. Locally measured BTCs were characterized by equivalent convection dispersion parameters: equivalent velocity, v(eq)(x) and expected equivalent dispersivity, [lambda(eq)(x)]. A Lagrangian framework was used to approximately predict these equivalent parameters in terms of the spatial covariance of log(e) transformed conductivity and the local scale dispersion coefficient. The approximate Lagrangian theory illustrates that [lambda(eq)(x)] increases with increasing travel distance and is much larger than the local scale dispersivity, lambda(d). A sensitivity analysis indicates that [lambda(eq)(x)] is predominantly determined by the transverse component of the local scale dispersion and by the correlation scale of the hydraulic conductivity in the transverse to flow direction whereas it is relatively insensitive to the longitudinal component of the local scale dispersion. By comparing predicted [lambda(eq)(x)] for a range of Dd values with [lambda(eq)(x)] obtained from locally measured BTCs, the transverse component of Dd, DdT, was estimated. The estimated transverse local scale dispersivity, lambda(dT) = DdT/U1 (U1 = mean advection velocity) is in the order of 10(1)-10(2) mm, which is relatively large but realistic for the fluvial gravel sediments at Krauthausen.
Jan Vanderborght; Harry Vereecken
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of contaminant hydrology     Volume:  54     ISSN:  0169-7722     ISO Abbreviation:  J. Contam. Hydrol.     Publication Date:  2002 Jan 
Date Detail:
Created Date:  2002-02-18     Completed Date:  2002-07-30     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  8805644     Medline TA:  J Contam Hydrol     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  141-71     Citation Subset:  IM    
Laboratory for Soil and Water, Katholieke Universiteit Leuven, Belgium.
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MeSH Terms
Chemistry, Physical
Geologic Sediments / chemistry
Models, Theoretical*
Physicochemical Phenomena
Water Movements*
Reg. No./Substance:

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