Effects of intraborehole flow on groundwater age distribution

Hydrogeology Journal
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Abstract

Environmental tracers are used to estimate groundwater ages and travel times, but the strongly heterogeneous nature of many subsurface environments can cause mixing between waters of highly disparate ages, adding additional complexity to the age-estimation process. Mixing may be exacerbated by the presence of wells because long open intervals or long screens with openings at multiple depths can transport water and solutes rapidly over a large vertical distance. The effect of intraborehole flow on groundwater age was examined numerically using direct age transport simulation coupled with the Multi-Node Well Package of MODFLOW. Ages in a homogeneous, anisotropic aquifer reached a predevelopment steady state possessing strong depth dependence. A nonpumping multi-node well was then introduced in one of three locations within the system. In all three cases, vertical transport along the well resulted in substantial changes in age distributions within the system. After a pumping well was added near the nonpumping multi-node well, ages were further perturbed by a flow reversal in the nonpumping multi-node well. Results indicated that intraborehole flow can substantially alter groundwater ages, but the effects are highly dependent on local or regional flow conditions and may change with time.

Publication type Article
Publication Subtype Journal Article
Title Effects of intraborehole flow on groundwater age distribution
Series title Hydrogeology Journal
DOI 10.1007/s10040-006-0139-8
Volume 15
Issue 4
Year Published 2007
Language English
Contributing office(s) Toxic Substances Hydrology Program
Description 11 p.
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Hydrogeology Journal
First page 633
Last page 643
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