Browsing by Author "Gran, Karen"

Now showing 1 - 5 of 5
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    Data for "Reducing High Flows and Sediment Loading through Increased Water Storage in an Agricultural Watershed of the Upper Midwest, USA"
    (2018-08-08) Mitchell, Nate A; Kumarasamy, Karthik; Cho, Se Jong; Belmont, Patrick; Dalzell, Brent; Gran, Karen; mitc0388@d.umn.edu; Mitchell, Nate A; University of Minnesota Duluth Geomorphology Lab
    Climate change, land clearing, and artificial drainage have increased the Minnesota River Basin’s (MRB) stream flows, enhancing erosion of channel banks and bluffs. Accelerated erosion has increased sediment loads and sedimentation rates downstream. High flows could be reduced through increased water storage (e.g., wetlands or detention basins), but quantifying the effectiveness of such a strategy remains a challenge. We used the Soil and Water Assessment Tool (SWAT) to simulate changes in river discharge from various water retention site (WRS) implementation scenarios in the Le Sueur watershed, a tributary basin to the MRB. We also show how high flow attenuation can address turbidity issues by quantifying the impact on near-channel sediment loading in the watershed’s incised reaches. WRS placement in the watershed, hydraulic conductivity (K), and design depth were varied across 135 simulations. The dominant control on site performance is K, with greater flow reductions allowed by higher seepage rates and less frequent overflowing. Deeper design depths enhance flow reductions from sites with low K values. Differences between WRS placement scenarios are slight, suggesting that site placement is not a first-order control on overall performance in this watershed. Flow reductions exhibit power-law scaling with exceedance probability, enabling us to create generalized relationships between WRS extent and flow reductions that accurately reproduce our SWAT results and allow for more rapid evaluation of future scenarios. Overall, we show that increasing water storage within the Le Sueur watershed can be an effective management option for high flow and sediment load reduction.
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    Geomorphic Change Detection and Site Documentation with Terrestrial Laser Scanning
    (2015-05-14) Gran, Karen
    Terrestrial laser scanning (TLS), also known as ground-based lidar, provides a way to rapidly collect high-resolution topographic data of a surface while minimizing disturbance. While aerial lidar data provides spatial resolutions in the 1-3 m range, TLS can provide data at cm-scale or even mm-scale resolution over a more limited area. This talk will focus on the basic workflow associated with collection and analysis of TLS data, the range of instruments available, and potential uses in archaeology. Examples cover a range of applications from site documentation to using repeat TLS scans to detect and quantify geomorphic change on a surface over time.
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    Le Sueur River Basin Sediment Characterization - chemical and physical properties of sediments collected 2015-2018
    (2019-02-14) Baker, Anna; Finlay, Jacques; Gran, Karen; Rorer, Michelle; Belo, Tessa; Atkins, Walter; Muramoto-Mathieu, Megumi; Yetter, Kara; Katherine, Kemmitt; abaker@usgs.gov; Baker, Anna
    These data were collected in support of the development of a watershed budget for sediment-derived phosphorus for the Le Sueur River Basin. This table presents the results of analyses of sediment total phosphorus and extractable dissolved phosphorus (soluble reactive phosphorus, SRP, or dissolved orthophosphate, DOP) and other chemical and physical parameters with potential influence over the phosphorus content of these sediments. This data set consists of 97 samples collected from erosional source areas including agricultural fields and ditches, near channel features such as bluffs, streambanks, and ravines, and from sinks such as channel beds and fluvial suspended sediment.
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    Management Option Simulation Model (MOSM) and supporting documents
    (2017) Cho, Se J.; Wilcock, Peter; Gran, Karen; Belmont, Patrick; Hobbs, Ben; Collaboratives for Sediment Source Reduction--Greater Blue Earth River Basin
    MOSM was developed in collaboration with scientists, engineers, and economists from three research universities (Johns Hopkins University, University of Minnesota (Twin Cities and Duluth), and Utah State University), and with a stakeholder group familiar with the watershed (agricultural producers, conservation groups, and members of state and local regulatory agencies). This collaborative development helped to identify relevant and plausible environmental management alternatives to include in the model, and guided development of the model structure, input data, and decision analysis. MOSM simulates movement of water and sediment across a watershed and evaluates the effects of various management option scenarios on sediment loading. It is a reduced-complexity watershed model where many components (i.e., spatial and temporal grids, and number of interacting state variables) and the degree of complexity (i.e., range of physical, chemical, and biological processes) have been reduced to include only those processes essential to represent sediment transport and surface water routing. MOSM is designed to be constrained by the best-available existing information, including stream gaging records, a complete watershed sediment budget, historical trends in the watershed, and independent measures of outputs, such as sediment fingerprinting and a suite of geomorphic change detection outputs.