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Multiscale Hyporheic Exchange Through Strongly Heterogeneous Sediments

Pryshlak, Timothy Theodozij
http://orcid.org/0000-0002-5958-9978
http://rave.ohiolink.edu/etdc/view?acc_num=osu1429803457

Abstract Details

2015, Master of Science, Ohio State University, Earth Sciences.
Hydraulic conductivity (K) heterogeneity and channel morphology both control surface water-groundwater exchange (hyporheic exchange), which influences stream ecosystem processes and biogeochemical cycles. Here I show that K heterogeneity is the dominant control on exchange rates, residence times, and patterns in hyporheic zones with sharp lithologic contrasts. I simulated hyporheic exchange in a representative low-gradient stream with 300 different bimodal K fields composed of sand and silt. K realizations span five sets of sand-silt ratios and two sets of low and high K contrasts (one and three orders of magnitude). K heterogeneity increases interfacial fluxes by orders of magnitude relative to homogeneous cases, drastically changes the shape of residence time distributions, and decreases median residence times. The positioning of highly permeable sand bodies controls patterns of interfacial flux and flow paths. These results are remarkably different from previous studies of smooth, continuous K fields that indicate only moderate effects on hyporheic exchange. The results also show that hyporheic residence times are least predictable when sand body connectivity is low. As sand body connectivity increases, the expected residence time distribution (ensemble average for a given sand-silt ratio) remains approximately constant, but the uncertainty around the expectation decreases. Including strong heterogeneity in hyporheic models is imperative for understanding hyporheic fluxes and solute transport. In streams with bimodal sediments, characterizing stark facies contrasts is more critical for predicting hyporheic exchange metrics than characterizing channel morphology.
Audrey Sawyer, Dr. (Advisor)
Michael Wilkins, Dr. (Committee Member)
Franklin Schwartz, Dr. (Committee Member)
88 p.
Geology; Hydrology
Hyporheic Zone; hyporheic exchange; hydraulic conductivity; heterogeneity; surface water-groundwater exchange

Recommended Citations

Citations

  • Pryshlak, T. T. (2015). Multiscale Hyporheic Exchange Through Strongly Heterogeneous Sediments [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1429803457

    APA Style (7th edition)

  • Pryshlak, Timothy. Multiscale Hyporheic Exchange Through Strongly Heterogeneous Sediments. 2015. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1429803457.

    MLA Style (8th edition)

  • Pryshlak, Timothy. "Multiscale Hyporheic Exchange Through Strongly Heterogeneous Sediments." Master's thesis, Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1429803457

    Chicago Manual of Style (17th edition)

osu1429803457
754
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This open access ETD is published by The Ohio State University and OhioLINK.