Date of Completion

4-25-2019

Embargo Period

4-24-2021

Keywords

Groundwater, CFD, Flow modeling, Porous media, Contaminant transport, Geophysics, Hyporheic zone, Mass transfer

Major Advisor

Amvrossios C. Bagtzoglou

Co-Major Advisor

Martin A. Briggs

Associate Advisor

Frederick D. Day-Lewis

Associate Advisor

Zoi Dokou

Field of Study

Environmental Engineering

Degree

Doctor of Philosophy

Open Access

Open Access

Abstract

The importance of the exchange between surface water (SW) and groundwater (GW) is well known among researchers because of its effects on multiple processes including contaminant transport, biogeochemical reactions, and remediation techniques. Thorough understanding of this exchange can be challenging due to the various factors that can impact GW-SW exchange dynamics; especially considering the possibility of sediment heterogeneity in porous media. In the presence of sediment heterogeneity, pores with different levels of connectivity are expected. Pores that are well connected create “mobile” zones, while poorly connected pores create “less-mobile” zones. Conventional fluid sampling techniques are primarily sensitive to the mobile zones, given the pumping mechanism of sampling. On the other hand, geoelectrical measurements are sensitive to both mobile and less-mobile zones. Therefore, a combination of fluid sampling and geoelectrical measurements in the presence of an ionic tracer can provide a much improved assessment of mobile and less-mobile zones and the exchange between these two porosity domains. We have incorporated this combined approach in numerical simulations and field studies of sediment/water interfaces in naturally occurring porous media such as a lake and an urban stream. Our results illustrate that this approach can provide a quantitative assessment of less-mobile porosity exchange dynamics, including their flow dependent behavior. Further, we also provide an investigation of the dependency of less-mobile zones on stream bedform attributes.

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