MC Buoy

Real-time Oceanographic Buoy for Lake Michigan

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MC Buoy

NDBC Buoy 45170 measures meteorological parameters as well as surface and subsurface lake temperatures, wave height, and wave direction.

In collaboration with Illinois-Indiana Sea Grant and the Höök Lab at Purdue, our lab has co-deployed and maintained NDBC Buoy 45170 since it was launched in 2012. This Lake Michigan buoy, located about 2 miles offshore from Michigan City, IN, measures standard meteorological parameters (wind speed, air temperature, etc.) as well as surface and subsurface lake temperatures, wave height, and wave direction. The buoy reports data in real time to both the NDBC buoy website as well as a dedicated Sea Grant website. It is typically deployed in early May and retrieved as late as November (fair weather days are hard to come by in November!). This buoy currently provides the only wave measurements along Indiana’s shoreline, which are the largest waves in Lake Michigan. Troy Lab members participate in the annual deployment, retrieval, and maintenance of the buoy as a valuable learning experience about what goes into oceanographic buoy data collection.

Collaborators

Illinois-Indiana Sea Grant; Tomas Höök, Purdue University; Limnotech

UAV SURVEY

Shoreline Surveys to Support Resilient Beaches

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UAV SURVEY

Performing a shoreline survey using Purdue’s LiDAR-equipped unmanned aerial vehicle

Also motivated by the recent high water levels in the Laurentian Great Lakes, this project aims to collect and disseminate timely shoreline data and analysis to Indiana shoreline managers and residents. For this project, we will be performing shoreline surveys using Purdue’s LiDAR-equipped unmanned aerial vehicle, as well as analyzing existing historical LiDAR data to assess Indiana’s shoreline changes in the context of historical changes.

Funding

Lake Michigan Coastal Program, Indiana Department of Natural Resources / NOAA

Collaborators

Ayman Habib, Purdue University

BevShores2019

An Integrated Physical-Social-Community (PSC) Approach for Sustainable Shore Protection, Beach Integrity, and Bluff/Dune Stabilization Along Lake Michigan

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Beverly Shores 2019 1500 x 600

Beverly Shores, IN beach

Recent record-high water levels across the Laurentian Great Lakes have shoreline communities scrambling to protect beaches, property, and infrastructure from rapid and widespread erosion. This current situation, and the uncertainty associated with lake levels in the future, underscores the need for comprehensive shoreline management strategies that will create resilient shorelines capable of buffering future conditions. However, shoreline protection strategies must be carefully implemented, ideally in a coordinated manner, since “hard” protection measures such as sea walls and revetments generally have large impacts on neighboring shorelines. Additionally, shoreline management does not merely involve applications of engineering principles to solve the problem; shorelines are highly social systems that require careful consideration of social and community perspectives.

This collaborative project, jointly funded by the Illinois-Indiana, Michigan, and Wisconsin Sea Grants tackles key physical, social, and community challenges associated with Lake Michigan shorelines. At Purdue we are particularly focused on the Illinois and Indiana shorelines, seeking to not only understand the physical mechanisms associated with the current shoreline state and erosion, but also to place the current state in historical perspective. Our work involves shoreline surveys (terrestrial and bathymetric), nearshore hydrodynamic and sediment measurements, and analysis of historical aerial imagery. Additional work by Dr. Aaron Thompson at Purdue is examining the attitudes and perceptions of Indiana and Illinois shoreline communities, particularly with respect to shoreline protection alternatives.

Funding

Illinois-Indiana Sea Grant, Michigan Sea Grant, Wisconsin Sea Grant

Collaborators

Chin Wu, University of Wisconsin-Madison; Guy Meadows and Pengfei Xue, Michigan Tech; Mark Brederland, Michigan State University; Aaron Thompson, Purdue University; and others.

LExplore Platform

Vertical Mixing and Basin-scale Energetics in Lake Geneva, Switzerland

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LExplore

L’Explore floating observational platform on Lake Geneva, Switzerland.

This project was developed during my sabbatical at the École Polytechnique Fédérale de Lausanne (EPFL) in Lausanne, Switzerland, where I was hosted by Dr. Johny Wüest. The objectives of the project were to quantify seasonal variations in vertical mixing in the lake, making use of the L’Explore Platform, and to link these observations of vertical mixing with the overall energetics of the lake. This one-of-a-kind floating observational platform is a moored 10m x 10m instrumented platform that contains continuously recording instruments and also serves as a deployment platform for episodic work. During my time there, we performed regular weekly microstructure sampling from the platform, as well as some intensive 24 hour experiments to examine biological variability.

Collaborators

Johny Wüest, Bieito Fernandez, Hugo Ulloa (EPFL); Damien Bouffard (EAWAG)

Inflatable Midlake

The Role of Near-inertial Poincaré Waves in Lake Michigan Mixing and Dispersion

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Inflatable Midlake

Microstructure profiling in the middle of Lake Michigan

Near-inertial internal waves are ubiquitous features in both large lakes and oceans. In large thermally-stratified lakes such as Lake Michigan, these basin-scale waves create strong near-surface currents that rotate clockwise (in the northern hemisphere) over a near-inertial period (~17.5 hours for Lake Michigan). The influence of these basin-scale waves, for which the thermocline movement represents a spinning coin, is particularly strong in the offshore waters, where the spiraling near-surface currents can have tide-like regularity, with magnitudes exceeding 50 cm/s. While these waves are readily observed in velocity and temperature measurements taken in large lakes, their influence on vertical mixing and lateral dispersion is not well-understood. This project examines two related hypotheses: (1) strong near-inertial shear drives cross-thermocline mixing; (2) lateral dispersion is enhanced by vertical shear associated with near-inertial wave currents. Our approach for this project is to carry out a set of field measurements involving moored instruments and microstructure cruises, as well as a large-scale dye and drifter release carried out in the center of Lake Michigan’s southern basin.

Funding

National Science Foundation, Division of Ocean Sciences, Physical Oceanography Program

Collaborators

Nathan Hawley, NOAA Great Lakes Environmental Research Laboratory

Quagga Bottom

The Role of Turbulence in Regulating Quagga Mussel Effects

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Since their arrival at the turn of this century, invasive quagga mussels have dramatically altered the food web in Lake Michigan. Quagga mussels now cover the bottom of much of Lake Michigan, particularly deeper waters, with densities exceeding 10,000 mussels per square meter in certain locations. As prolific filter-feeders, quagga mussels can filter up to several liters of water per day. The increased water clarity of Lake Michigan may seem like a good thing (Lake Michigan’s water clarity now rivals Lake Tahoe), but these hardy “ecosystem engineers” have had a dramatic effect on Lake Michigan’s ecosystem, causing species extinction, alterations to nutrient cycling, and benthic substrate changes. Quagga mussels have invaded all of the Great Lakes except for Lake Superior, and are currently colonizing deeper reservoirs in the Western U.S. as well as lakes in Western Europe (among other places).

The ability of quagga mussels to clear the water column depends strongly on the turbulent mixing characteristics of the overlying water, Our ability to model the effects of mussels on aquatic systems depends then in turn on our abilities to model turbulent mixing in large lakes and oceans. When mixing is weak, mussels can only filter a small volume of water around them; when turbulence is energetic, new water is continually delivered to the lake bed, and mussels effectively have access to the entire water column. Our role in this collaborative project, which focuses on quagga mussel dynamics in the deeper waters of Lake Michigan, is to quantify deep water mixing rates and to link these rates to mussel effects on the food web. To address these objectives, we are carrying out and analyzing a set of Lake Michigan field experiments, in a range of locations and conditions, where we measure water column temperatures, currents, and turbulence using a range of instrumentation and analysis techniques. The mixing prescriptions elucidated from these observations will then serve as the basis for a mixing model onto which we layer nutrient, plankton, and zooplankton models (NPZD).

Funding

National Science Foundation, Division of Ocean Sciences

Project home page – NSF BCO-DMO

Collaborators

Harvey Bootsma and Qian Liao, University of Wisconsin-Milwaukee

David Cannon, University of Michigan

Drifter Trajectories

Lateral dispersion of dye and drifters in the center of a very large lake

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To better understand lateral dispersion of buoyant and nonbuoyant pollutants within the surface waters of large lakes, two lateral dispersion experiments were carried out in Lake Michigan during the stratified period: (1) a dye tracking experiment lasting 1 d; and (2) a drifter tracking experiment lasting 24 d. Both the dye patch and drifters were surface-released at the center of Lake Michigan’s southern basin. Near-surface shear induced by near-inertial Poincaré waves partially explains elevated dye dispersion rates (1.5–4.2 m2 s−1). During the largely windless first 5 d of the drifter release, the drifters exhibited nearly scale-independent dispersion ( K ∼ L0.2), with an average dispersion coefficient of 0.14 m2 s−1. Scale-dependent drifter dispersion ensued after 5 d, with K ∼ L1.09 and corresponding dispersion coefficients of 0.3–2.0 m2 s−1 for length scales L = 1500–8000 m. The largest drifter dispersion rates were found to be associated with lateral shear-induced spreading along a thermal front. Comparisons with other systems show a wide range of spreading rates for large lakes, and larger rates in both the ocean and the Gulf of Mexico, which may be caused by the relative absence of submesoscale processes in offshore Lake Michigan.

Habib UAV

Evaluation of UAV LiDAR for mapping coastal Environments

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Unmanned Aerial Vehicle (UAV)-based remote sensing techniques have demonstrated great potential for monitoring rapid shoreline changes. With image-based approaches utilizing Structure from Motion (SfM), high-resolution Digital Surface Models (DSM), and orthophotos can be generated efficiently using UAV imagery. However, image-based mapping yields relatively poor results in low textured areas as compared to those from LiDAR. This study demonstrates the applicability of UAV LiDAR for mapping coastal environments. A custom-built UAV-based mobile mapping system is used to simultaneously collect LiDAR and imagery data. The quality of LiDAR, as well as image-based point clouds, are investigated and compared over different geomorphic environments in terms of their point density, relative and absolute accuracy, and area coverage. The results suggest that both UAV LiDAR and image-based techniques provide high-resolution and high-quality topographic data, and the point clouds generated by both techniques are compatible within a 5 to 10 cm range. UAV LiDAR has a clear advantage in terms of large and uniform ground coverage over different geomorphic environments, higher point density, and ability to penetrate through vegetation to capture points below the canopy. Furthermore, UAV LiDAR-based data acquisitions are assessed for their applicability in monitoring shoreline changes over two actively eroding sandy beaches along southern Lake Michigan, Dune Acres, and Beverly Shores, through repeated field surveys. The results indicate a considerable volume loss and ridge point retreat over an extended period of one year (May 2018 to May 2019) as well as a short storm-induced period of one month (November 2018 to December 2018). The foredune ridge recession ranges from 0 m to 9 m. The average volume loss at Dune Acres is 18.2 cubic meters per meter and 12.2 cubic meters per meter within the one-year period and storm-induced period, respectively, highlighting the importance of episodic events in coastline changes. The average volume loss at Beverly Shores is 2.8 cubic meters per meter and 2.6 cubic meters per meter within the survey period and storm-induced period, respectively.