Browsing by Author "Hill, Craig"
Now showing 1 - 6 of 6
Results Per Page
Sort Options
Item Aquatic Habitat Mapping in the St. Louis River Estuary(University of Minnesota Duluth, 2020-06) Reschke, Carol; Hill, CraigThe goal of this project has been to use data from recent aquatic vegetation sampling in the St. Louis River estuary to refine aquatic habitat maps for four restoration sites and four reference sites that can serve as models for restoration design and management. These aquatic habitat maps are designed for use by resource managers working to restore impaired habitats. St. Louis River estuary restoration plans are part of the multi-agency St. Louis River Area of Concern Remedial Action Plan (RAP) to restore fish and wildlife habitats and remove impairments that led to listing the St. Louis River as a Great Lakes Area of Concern (MPCA and WDNR 2013). This 12,000-acre freshwater estuary was designated an Area of Concern in the 1980s because legacy contaminants and disturbances led to nine key impairments, including loss of fish and wildlife habitat. Current restoration plans rely on aquatic habitat maps prepared for the 2002 Lower St. Louis River Habitat Plan (Appendix 1, Map 1); the original aquatic habitat polygons were drawn using minimal data on aquatic vegetation (SLRCAC 2002). The classification of aquatic habitats used in the 2002 Habitat Plan was qualitative, based primarily on the extensive expertise of local fisheries biologists. Since 2008, biologists in Minnesota and Wisconsin have conducted field surveys yielding over 3000 samples for aquatic and wetland vegetation in 23 key restoration and reference sites within the estuary. The objectives of this project were to 1) identify restoration site mapping priorities and appropriate reference sites, and compile existing data on aquatic vegetation, water depths, and wind fetch as characterized by relative exposure index (REI) for the estuary; 2) run hydrodynamic models for at least four scenarios of river discharge and Lake Superior water levels and extract data on water velocities and temperatures at vegetation sample sites; 3) use multivariate analyses to classify aquatic habitats based on aquatic and wetland plant communities and associated environmental data, and prepare habitat maps and supporting data for four restoration sites and four reference sites; and 4) share progress on this project with estuary resource managers at least five times during the project period, at meetings of the St. Louis River Estuary Habitat Work Group.Item Hydrokinetic turbine array performance and geomorphic effects under different siting strategies and sediment transport conditions: topography, flow velocity and array performance measurements(2019-06-27) Musa, Mirko; Hill, Craig; Guala, Michele; mguala@umn.edu; Guala, Michele; Saint Anthony Falls Laboratory, CEGE, University of MinnesotaHydrokinetic energy can be extracted efficiently from naturally occurring water flows. Although representing a continuous and ubiquitous source of kinetic energy, rivers in particular are delicate environments, sensitive to external disturbances. Asymmetric installation of in-stream hydrokinetic energy converters have proven to actively interact with sediment transport and bedforms characteristics, triggering non-local geomorphic effects that resemble river instabilities known as forced-bars. This data-set comprises a series of measurements of channel topography evolution, flow velocity around the turbines and array performance under different configurations.Item Interactions Between Channel Topography and Hydrokinetic Turbines: Sediment Transport, Turbine Performance, and Wake Characteristics(2015-08) Hill, CraigAccelerating marine hydrokinetic (MHK) renewable energy development towards commercial viability requires investigating interactions between the engineered environment and its surrounding physical and biological environments. Complex and energetic hydrodynamic and morphodynamic environments desired for such energy conversion installations present difficulties for designing efficient yet robust sustainable devices, while permitting agency uncertainties regarding MHK device environmental interactions result in lengthy and costly processes prior to installing and demonstrating emerging technologies. A research program at St. Anthony Falls Laboratory (SAFL), University of Minnesota, utilized multi-scale physical experiments to study the interactions between axial-flow hydrokinetic turbines, turbulent open channel flow, sediment transport, turbulent turbine wakes, and complex hydro-morphodynamic processes in channels. Model axial-flow current-driven three-bladed turbines (rotor diameters, dT = 0.15m and 0.5m) were installed in open channel flumes with both erodible and non-erodible substrates. Device-induced local scour was monitored over several hydraulic conditions and material sizes. Synchronous velocity, bed elevation and turbine performance measurements provide an indication into the effect channel topography has on device performance. Complimentary experiments were performed in a realistic meandering outdoor research channel with active sediment transport to investigate device interactions with bedform migration and secondary turbulent flow patterns in asymmetric channel environments. The suite of experiments undertaken during this research program at SAFL in multiple channels with stationary and mobile substrates under a variety of turbine configurations provides an in-depth investigation into how axial-flow hydrokinetic devices respond to turbulent channel flow and topographic complexity, and how they impact local and far-field sediment transport characteristics. Results provide the foundation for investigating advanced turbine control strategies for optimal power production in non-stationary environments, while also providing a robust data-set for computational model validation for further investigating the interactions between energy conversion devices and the physical environment.Item Physical Model Study of Marmot Dam Removal: Cofferdam Notch Location and Resulting Fluvial Responses(St. Anthony Falls Laboratory, 2007-09) Marr, Jeffrey D.G.; Hill, Craig; Johnson, Sara; Grant, Gordon; Campbell, Karen; Mohseni, OmidThis report summarizes observations made for a set of experiments conducted using the physical model of the Sandy River and Marmot Dam constructed for Portland General Electric (PGE). The experiments focused on the location of the cofferdam notch and its impact on the immediate sediment remobilization, knickpoint location and trajectory, volume of removal, and location of stranded sediment. The motivation for the study was to provide insights on how and if the position of a cofferdam notch will have an impact on how the site fails and how the reservoir sediments are remobilized. Based on early experiments with the model, PGE expressed concern that some failure scenarios resulted in abandonment of large terraces of sediment near the dam site, posing potential public safety issues. One goal of these experiments was to determine if cofferdam notch location could be positioned to minimize the volume of sediment stranded in terraces. Eight model scenarios were completed for this study. Seven of the scenarios examined a failure discharge of 2500 cfs (cubic feet per second), the minimum failure design discharge. Within these seven scenarios, we examined three notch positions; river right (north bank of river), center, and river left (south bank of river). In an eighth scenario we examined a river right notch location and failure at a high discharge of 5500 cfs. Sediment mixtures used in the model were scaled to sediment core data of the Sandy River reservoir sediment. The data and observations indicate that at the minimum design failure discharge of 2500 cfs, notch position does impact the location of cofferdam failure as well as the location of the first major knickpoint and its trajectory. The data suggest that a river left notch position minimizes the extent of stranded sediment terraces and a river right notch tends to result in larger terraces. A center notch position yielded similar results to the river right notch. At a discharge of 5500 cfs, results suggest that notch position is less important than at lower discharge rates, as the knickpoint is more or less bank to bank and is able to mobilize sediment more effectively.Item Scaled Hydrokinetic Turbine Array installed in a laboratory channel and flood-like sediment transport conditions: topography, flow velocity and array model performance(2019-06-26) Musa, Mirko; Hill, Craig; Sotiropoulos, Fotis; Guala, Michele; mguala@umn.edu; Guala, Michele; Saint Anthony Falls Laboratory, CEGE, University of MinnesotaThe data represent sediment flux, spatio-temporally resolved topographic scans, flow velocity and voltage from the hydrokinetic turbine array experiments presented in the referenced scientific article published on Nature Energy (see reference). Hydrokinetic Energy represents a viable source of renewable energy that harness the kinetic energy of natural currents. Our experiments show that this technology can be deployed efficiently in large sandy rivers (e.g. Mississippi River), without compromising the geomorphic equilibrium of the stream and the structural safety of the turbine foundation, even in the presence of large migrating dunes.Item StreamLab06: Overview of Experiments, Instrumentation, and Data collection(St. Anthony Falls Laboratory, 2010-11) Marr, Jeff; Wilcock, Peter; Hondzo, Miki; Foufoula-Georgiou, Efi; Johnson, Sarah; Hill, Craig; Leonardson, Rebecca; Nelson, Peter; Venditti, Jeremy; O'Connor, Ben; Ellis, Christopher R.; Mullin, James; Jefferson, Anne; Clark, JeffThis report summarizes the StreamLab06 experimental research program conducted in the St. Anthony Falls Laboratory (SAFL) Main Channel facility from April through October 2006. The experiments were funded through the National Center for Earth-surface Dynamics and involved a host of researchers, graduate students, visitors, and undergraduate students. The experiments were organized into seven phases of work. The first two phases of the project involved testing of conventional and surrogate bedload monitoring technologies (Marr et. al. 2007). The last five phases involved interdisciplinary research of sediment transport and ecohydraulics. This report focuses on the later phases of the project and does not include the bedload monitoring technologies. This report contains information on the organization of the experiments, the methodologies and protocols used to collect data, the types of data collected, data structure and format, and information on data storage and access.