• Login
    View Item 
    •   Home
    • Theses & Dissertations
    • 2019 - Mines Theses & Dissertations
    • View Item
    •   Home
    • Theses & Dissertations
    • 2019 - Mines Theses & Dissertations
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Browse

    All of Mines RepositoryCommunitiesPublication DateAuthorsTitlesSubjectsThis CollectionPublication DateAuthorsTitlesSubjects

    My Account

    Login

    Mines Links

    Arthur Lakes LibraryColorado School of Mines

    Statistics

    Display Statistics

    Electrical imaging of hyporheic exchange from channel-spanning logjams

    • CSV
    • RefMan
    • EndNote
    • BibTex
    • RefWorks
    Thumbnail
    Name:
    Doughty_mines_0052N_11728.pdf
    Size:
    1.347Mb
    Format:
    PDF
    Download
    Author
    Doughty, Megan
    Advisor
    Singha, Kamini
    Date issued
    2019
    Keywords
    hydrology
    logjam
    hyporheic
    electrical resistivity
    
    Metadata
    Show full item record
    URI
    https://hdl.handle.net/11124/173062
    Abstract
    Human impacts such as timber harvesting, engineered channels, beaver removal, and urbanization can alter the inherent characteristics and features of streams, which affect their natural physical and chemical states. One such feature substantially diminished by anthropogenic changes is the development of blockages from fallen trees and loose wood in streams. These logjams increase hydraulic resistance and create hydraulic head gradients along the streambed that drive groundwater-surface water exchange. This exchange occurs in saturated sediment under and around a stream, called the hyporheic zone, where surface water and groundwater mix. Hyporheic exchange has an important influence on a stream’s ecosystem, because it transfers dissolved oxygen, solutes, and nutrients into the subsurface as well as mediates temperature fluctuations. Here, we focus on quantifying the changes in hyporheic exchange flow (HEF) due to channel-spanning logjams. Field measurements and numerical modeling using MODFLOW and MT3D were used in this study to explore logjam-induced hyporheic exchange. The traditional methods for characterizing HEF, such as in-stream and well monitoring, fail to capture the complex hyporheic processes because they only provide point measurements. Electrical resistivity imaging (ERI), a surface-based geophysical method, was used to monitor the transport of solutes into the hyporheic zone during an in-stream tracer test supplemented by in-stream monitoring. ERI provides spatial and temporal data on the distribution of subsurface bulk electrical resistivity. We ran ERI at two reaches in Little Beaver Creek, CO: one with a single logjam and the second at a control reach with no logjams. Our results show that 1) higher HEF occurred at the reach with a logjam than the one without, and that 2) higher discharge rates associated with spring snowmelt increase the extent and magnitude of HEF, while 3) lower flows may increase the residence time in the hyporheic zone. The numerical modeling in MODFLOW and MT3D supports the finding that logjams increase the extent and rate of HEF. This research has implications for quantifying the controls of natural stream heterogeneity, the transport of sediment, the health of the stream’s ecosystem, and improving stream restoration and conservation efforts.
    Rights
    Copyright of the original work is retained by the author.
    Collections
    2019 - Mines Theses & Dissertations

    entitlement

     
    DSpace software (copyright © 2002 - 2023)  DuraSpace
    Quick Guide | Contact Us
    Open Repository is a service operated by 
    Atmire NV
     

    Export search results

    The export option will allow you to export the current search results of the entered query to a file. Different formats are available for download. To export the items, click on the button corresponding with the preferred download format.

    By default, clicking on the export buttons will result in a download of the allowed maximum amount of items.

    To select a subset of the search results, click "Selective Export" button and make a selection of the items you want to export. The amount of items that can be exported at once is similarly restricted as the full export.

    After making a selection, click one of the export format buttons. The amount of items that will be exported is indicated in the bubble next to export format.