Geophysical Imaging of Hyporheic Mixing Dynamics Within Compound Bar Deposits
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| Language: | English |
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University of Cincinnati / OhioLINK
2021
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| Online Access: | http://rave.ohiolink.edu/etdc/view?acc_num=ucin1617109253147661 |
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ndltd-OhioLink-oai-etd.ohiolink.edu-ucin16171092531476612021-10-01T05:11:02Z Geophysical Imaging of Hyporheic Mixing Dynamics Within Compound Bar Deposits McGarr, Jeffery T. Geology hyporheic exchange electromagnetic induction electrical resistivity imaging compound bar heterogeneity geophysics Interactions between surface water and groundwater (hyporheic exchange) influence water quality and control numerous physical, chemical, and biological processes. Despite its importance, hyporheic exchange and the associated dynamics of solute mixing are often difficult to characterize due to spatial (e.g., sedimentary heterogeneity) and temporal (e.g., river stage fluctuation) variabilities. This study coupled geophysical techniques with physical and chemical sediment analyses to quantify hyporheic exchange dynamics in a compound bar deposit within a gravel-dominated river system in southwestern Ohio. Electromagnetic induction (EMI) was used to quantify variability in electrical conductivity within the compound bar. A zone of high electrical conductivity was clearly identified as a fine-grained cross-bar channel fill. Differences in the physical and geochemical characteristics of such channel fills play an important role in hyporheic flow dynamics and nutrient processing. EMI informed locations of electrode placement for time-lapse electrical resistivity imaging surveys to examine changes in electrical resistivity driven by hyporheic exchange, revealing preferential flow paths through high-permeability sediments. Grain size analyses confirmed interpretations of geophysical data, and loss on ignition and x-ray fluorescence identified more favorable locations for enhanced geochemical and microbial activity as cross-bar channel fills identified through EMI measurements. These findings provide fundamental insights into hyporheic exchange, and the technical framework presented in this study has implications for improving future studies of hyporheic dynamics and numerical model development through more accurate representation of geomorphologic features and sediment heterogeneity. 2021-09-29 English text University of Cincinnati / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=ucin1617109253147661 http://rave.ohiolink.edu/etdc/view?acc_num=ucin1617109253147661 restricted--full text unavailable until 2022-03-30 This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws. |
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NDLTD |
| language |
English |
| sources |
NDLTD |
| topic |
Geology hyporheic exchange electromagnetic induction electrical resistivity imaging compound bar heterogeneity geophysics |
| spellingShingle |
Geology hyporheic exchange electromagnetic induction electrical resistivity imaging compound bar heterogeneity geophysics McGarr, Jeffery T. Geophysical Imaging of Hyporheic Mixing Dynamics Within Compound Bar Deposits |
| author |
McGarr, Jeffery T. |
| author_facet |
McGarr, Jeffery T. |
| author_sort |
McGarr, Jeffery T. |
| title |
Geophysical Imaging of Hyporheic Mixing Dynamics Within Compound Bar Deposits |
| title_short |
Geophysical Imaging of Hyporheic Mixing Dynamics Within Compound Bar Deposits |
| title_full |
Geophysical Imaging of Hyporheic Mixing Dynamics Within Compound Bar Deposits |
| title_fullStr |
Geophysical Imaging of Hyporheic Mixing Dynamics Within Compound Bar Deposits |
| title_full_unstemmed |
Geophysical Imaging of Hyporheic Mixing Dynamics Within Compound Bar Deposits |
| title_sort |
geophysical imaging of hyporheic mixing dynamics within compound bar deposits |
| publisher |
University of Cincinnati / OhioLINK |
| publishDate |
2021 |
| url |
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1617109253147661 |
| work_keys_str_mv |
AT mcgarrjefferyt geophysicalimagingofhyporheicmixingdynamicswithincompoundbardeposits |
| _version_ |
1719486502293995520 |