Apparent dispersion in transient groundwater flow

Water Resources Research
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Abstract

This paper investigates the effects of large-scale temporal velocity fluctuations, particularly changes in the direction of flow, on solute spreading in a two-dimensional aquifer. Relations for apparent longitudinal and transverse dispersivity are developed through an analytical solution for dispersion in a fluctuating, quasi-steady uniform flow field, in which storativity is zero. For transient flow, spatial moments are evaluated from numerical solutions. Ignored or unknown transients in the direction of flow primarily act to increase the apparent transverse dispersivity because the longitudinal dispersivity is acting in a direction that is not the assumed flow direction. This increase is a function of the angle between the transient flow vector and the assumed steady state flow direction and the ratio of transverse to longitudinal dispersivity. The maximum effect on transverse dispersivity occurs if storativity is assumed to be zero, such that the flow field responds instantly to boundary condition changes.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Apparent dispersion in transient groundwater flow
Series title Water Resources Research
DOI 10.1029/WR026i010p02339
Volume 26
Issue 10
Year Published 1990
Language English
Publisher American Geophysical Union
Contributing office(s) Pennsylvania Water Science Center
Description 13 p.
First page 2339
Last page 2351