Simulating water-quality trends in public-supply wells in transient flow systems

Ground Water
By: , and 

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Abstract

Models need not be complex to be useful. An existing groundwater-flow model of Salt Lake Valley, Utah, was adapted for use with convolution-based advective particle tracking to explain broad spatial trends in dissolved solids. This model supports the hypothesis that water produced from wells is increasingly younger with higher proportions of surface sources as pumping changes in the basin over time. At individual wells, however, predicting specific water-quality changes remains challenging. The influence of pumping-induced transient groundwater flow on changes in mean age and source areas is significant. Mean age and source areas were mapped across the model domain to extend the results from observation wells to the entire aquifer to see where changes in concentrations of dissolved solids are expected to occur. The timing of these changes depends on accurate estimates of groundwater velocity. Calibration to tritium concentrations was used to estimate effective porosity and improve correlation between source area changes, age changes, and measured dissolved solids trends. Uncertainty in the model is due in part to spatial and temporal variations in tracer inputs, estimated tracer transport parameters, and in pumping stresses at sampling points. For tracers such as tritium, the presence of two-limbed input curves can be problematic because a single concentration can be associated with multiple disparate travel times. These shortcomings can be ameliorated by adding hydrologic and geologic detail to the model and by adding additional calibration data. However, the Salt Lake Valley model is useful even without such small-scale detail.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Simulating water-quality trends in public-supply wells in transient flow systems
Series title Ground Water
DOI 10.1111/gwat.12230
Volume 52
Issue S1
Year Published 2014
Language English
Publisher Wiley
Contributing office(s) Connecticut Water Science Center
Description 10 p.
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Ground Water
First page 53
Last page 62
Country United States
State Utah
Other Geospatial Salt Lake Valley