Browsing by Author "Behar, Hannah"

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    Data for Impacts of beaver dams on low-flow hydrology and hydraulics, Knife River, Minnesota
    (2021-06-07) Gran, Karen B; Behar, Hannah; Burgeson, Emma; Dymond, Salli; Dumke, Josh; Teasley, Rebecca; kgran@d.umn.edu; Gran, Karen B
    These data were collected as part of a two-year investigation into the impacts of beaver dam removal on low-flow hydrology and hydraulics in the Knife River, Minnesota, USA. Eight sub-basins were monitored for two years, organized as four pairs of sub-basins. The study focused on small headwater sub-basins, with areas ranging from 1.58 to 6.4 km2. In 2018, all of the study basins had active beaver dams. In 2019, the beavers were removed and dams notched in half of the sub-basins, one half of each of the four pairs. Data collection continued throughout the 2019 season measuring impacts post-dam removal.
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    Modeling Stream Thermal Dynamics: The Influence of Beaver Dams in a Minnesota Watershed
    (2020-08) Behar, Hannah
    Beaver dams are known to alter the thermal regime of ponds, streams, and adjacent subsurface waters. Downstream of a dam, stream temperature is influenced by increased exchange with the hyporheic zone, which may cool and buffer the stream’s diel temperature cycles. Concurrently, reduced shading in the beaver forage zone is likely to increase heat flux at the stream-atmosphere boundary. The dynamics of these processes can be analyzed to understand how stream temperature is affected on diel time scales, as well as longitudinally at distances downstream from the dam. At two beaver dam-impacted stream sites in the Knife River Watershed in Minnesota, USA, I monitored in-stream and shallow subsurface flow and temperature during low-flow summer conditions. I used a dye tracer test, vertical heat transport modelling, and soil characterization to estimate flux through the streambed at multiple locations. Temperature, stream flow, and atmospheric data were also collected throughout the summer from the two sites. A one-dimensional model of longitudinal stream temperature, calibrated to in-stream temperature measurements, was developed to determine which physical parameters and heat flux components have the greatest influence on stream temperature. The model was then used to demonstrate how these changes persist downstream, as well as to simulate stream temperature under potential future site conditions. These findings increase scientific understanding of stream temperature regime in the context of beaver dam-altered watersheds.