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High-resolution physical and biogeochemical field data in central Lake Erie during the summers of 2008-2009 along with a three-dimensional numerical model were used to investigate the dynamics of basin scale waves and sediment resuspension mechanisms. In Chapter 2, the modal response of the Poincaré waves in the lake is assessed. The vertical mode-one Poincaré wave was found to be mostly dominant during the seasonal stratified period. The horizontal modal structure was also investigated in a sensitivity analysis, using the numerical model forced with real and idealized wind events. In Chapter 3, dynamics of bottom mixed layer (BML), primarily forced in the outer layer by surface seiches and Poincaré waves is studied for two 10-days representative intervals of weak and strong stratification. Shear velocity was calculated by least square fitting the well-known law-of-the-wall equation to observed near-bed velocity in a region of constant shear stress. Height of the BML is computed using water density (from water temperature) and compared with heights of logarithmic layer approximated using the law-of-the-wall equation and its modified form with buoyancy length scale term. Published equations for estimating BML heights are evaluated and modified for the lake. In Chapter 4, we investigate physical processes leading to sediment resuspension in the lake including surface waves (periods of 4-8s), up/downwelling events (periods of 3-4 day), and high frequency internal waves (periods of 5-45min). Temporal changes in near-bottom sediment resuspension are illustrated using changes in acoustic backscatter signals from current profilers and time series of turbidity measurements to identify the mechanism responsible for sediment resuspension. Resuspension is parameterized as a function of the critical velocity ~0.25ms-1 and from surface waves using linear wave theory. Finally, based on the critical velocity and sediment grain size analysis (from in-site field data), critical shear stress and Shields parameter are calculated and compared with previous observations in Lake Erie and in other locations suggesting a modified Shields diagram for silty bed materials. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2012-12-19 20:54:15.832

Since their introduction to Lake Erie, dreissenid mussels may have reengineered the cycling of nutrients in the lake so that the nearshore benthic community intercepts, retains, and recycles greater quantities of nutrients. This study traces particulate matter on a basin scale by characterizing the chemical composition (POC and PN concentrations, POC/PN mass ratios, δ¹³C and δ¹⁵N) of suspended particulate matter in Lake Erie, three tributary inflows, and the lake outflow between May and October, 2002. The data are used to 1) determine the relative contributions of allochthonous and autochthonous sources to suspended particulate matter, 2) identify possible sources of suspended particulate matter, and 3) compare suspended particulate matter in the eastern basin of Lake Erie with that in the central and western basins. Mean POC concentrations range from 175 to 4494 ??g/L and mean PN concentrations range from 33 to 812 ??g/L in this system. Mean POC/PN mass ratios are similar across all sampling locations, ranging between 4. 5 and 6. 9, and indicate that suspended particulate matter at these sites is mainly derived from autochthonous sources, particularly plankton. The ranges of δ¹³C (-34 to -22 ?) and δ¹⁵N (1 to 12 ?) identify terrestrial plants and soil matter, aquatic macrophytes, phytoplankton, and sewage as possible sources of suspended particulate matter at all sites. Plankton is probably the dominant source of suspended particulate matter at each site, with smaller contributions from allochthonous and other autochthonous sources. Significant differences in the concentration and isotope data between inflow and lake or outflow sites indicate that tributary inflows may receive greater contributions from terrestrial plants and soils and aquatic macrophytes than the lake and outflow. δ¹⁵N signatures also identify animal manure as a possible source of suspended particulate matter at the inflows. PN concentrations and δ¹⁵N signatures suggest that the shallowest nearshore sites close to Peacock Point in the eastern basin receive PN from a source that is not present at the other eastern basin sites or at the sites in the central and western basins. This source may be related to dreissenid mussels at these nearshore sites recycling nitrogen back into the water column.

<em>Cladophora glomerata</em> is a filamentous green alga that currently forms extensive blooms in nearshore areas of Lake Ontario, eastern Lake Erie, Lake Michigan, and isolated locations in Lake Huron. The biomass, areal coverage, algal bed characteristics, and tissue phosphorus concentrations of <em>Cladophora glomerata</em> were measured at 24 nearshore rocky sites along the northern shoreline of Lake Erie?s eastern basin between 1995-2002. Midsummer areal coverage at shallow depths (&le;5m) ranged from 4-100 %, with a median value of 96%. Peak seasonal biomass ranged from <1 to 940 g m^-2 dry mass (DM), with a median value of 171 g m^-2 DM. Tissue phosphorus varied seasonally, with initial high values in early May (0. 15 to 0. 27 % DM; median 0. 23 % DM) to midsummer seasonal low values during peak biomass (0. 03 to 0. 23 % DM; median 0. 06 % DM). A numerical <em>Cladophora</em> growth model (CGM) was revised and field-tested at 5 sites in eastern Lake Erie during 2002. The CGM is useful for: 1) Predicting <em>Cladophora</em> growth, biomass, and tissue phosphorus concentrations under non-point source P loading with no depth restrictions; 2) providing estimates of the timing and magnitude of the midsummer sloughing phenomenon; 3) determining the contribution of <em>Dreissena</em> invasion to the resurgence of <em>Cladophora</em> in eastern Lake Erie; and 4) developing management strategies for <em>Cladophora</em> abatement. The CGM was applied to investigate how the spatial and temporal patterns of <em>Cladophora</em> growth were influenced by the natural variability in environmental parameters in eastern Lake Erie. Seasonal patterns in <em>Cladophora</em> growth were strongly influenced by temperature, and peak depth-integrated biomass was strongly influenced by both available light and phosphorus. The photosynthetic capacity of field collected <em>Cladophora</em> was a poor predictor of the mid-summer sloughing phenomenon. The CGM, however, predicted that self-shading within the dense <em>Cladophora</em> mats would have caused negative growth rates at the base of the dense mats for 14 days prior to the sloughing event. The metabolic imbalances at the base of the <em>Cladophora</em> mats were driven primarily by the availability of light and were exacerbated by intermediate water temperatures (~23??C). The excellent agreement between model simulations and field data illustrates the ability of the CGM to predict tissue P and growth over a range of sites and depths in eastern Lake Erie and suggests potential for the model to be successfully applied in other systems.

This thesis is about the act of inhabiting the post-industrial landscape: about how a city with the remains of and scars from a previous era can begin to repurpose those remnants--both in a physical, as well as intangible sense. Proposing an alternative to the patterns of development that created such a landscape, it offers resistance to the entrenched values of privatization, commodification, and consumption. The chosen site--an abandoned grain elevator in Buffalo, New York--sits at a nexus of converging landscapes: the grid of downtown to the north, a former industrial canal to the east, a stretch of barren waterfront land to the south, and the expansive Lake Erie to the west. This site, existing at the mouth of the now contaminated Buffalo River, possesses both beauty and sublimity in its deterioration; as such, it is uniquely situated to become a charged point of entry to the desolate waterfront beyond, as well as a bridge--literally and figuratively--between the city, its heritage, and its legacy. Drawing on such precedents as the library and the enlightenment-era salon as traditional places of scholarship and colloquy, the project is also influenced by the archetypes of the tavern and the union hall as more informal, although no less vital, places of cultural exchange. It is the aim of this thesis to bring the residents of Buffalo together in a public platform that would impress and bring into focus the processes that created the current conditions, allow for the meaningful re-inhabitation of this landscape, as well as foster a sense of community, dialogue, exchange, learning, and inquiry, with the desired outcome of participatory change.

This thesis investigates physical processes in Lake Erie, a large, shallow mid-latitude lake, from two perspectives: climate change impacts on the thermal structure and dissolved oxygen concentration and small-scale eddy dynamics generated by internal Kelvin wave propagation. A three-dimensional hydrodynamic and aquatic ecological coupled model ELCOM-CAEDYM, validated by the field data collected in 2008, is first used to investigate the responses of the thermal structure and dissolved oxygen concentration in Lake Erie to potential changes in air temperature and wind speed. A new method is presented to define spatially and temporally varying regions for the epilimnion, thermocline, and hypolimnion. Four metrics are selected to quantify the characteristics of the thermal structure: mean epilimnion temperature, mean hypolimnion temperature, onset and breakdown of stratification, and thermocline depth. Exploiting the power of the three dimensional model to provide a more authentic characterization of thermal structure in such large lakes, it is shown that patterns inferred from simple isotherm dynamics, as typically done with one dimensional models, are not always accurate. In the dissolved oxygen studies similar analyses are presented. Three factors related to lake hydrodynamics have strong influences on hypolimnetic hypoxia: water temperature, stratification duration, and hypolimnion thickness. The present results show the potential for complicated and interactive effects of climate forcing on important biogeochemical processes in Lake Erie as well as other large mid-latitude lakes. Taking advantage of high performance computing, the generation of eddies when a baroclinic Kelvin wave propagates past a peninsula is studied using the MITgcm. The grid resolution can be refined from 2 km to 200 m in the parallel computing environment. With the finer resolution small-scale processes which cannot be resolved in the coarse resolution applied previously are able to be explored. The eddy dynamics are studied in detail in both an idealized lake and in Lake Erie. This work presents a first attempt at simulating small-scale hydrodynamic processes in large lakes and contributes to our understanding of how energy is moved from large scales (the scale of the basins in Lake Erie) to smaller scales (the scale of the peninsula or Point Pelee).

Since their introduction to Lake Erie, dreissenid mussels may have reengineered the cycling of nutrients in the lake so that the nearshore benthic community intercepts, retains, and recycles greater quantities of nutrients. This study traces particulate matter on a basin scale by characterizing the chemical composition (POC and PN concentrations, POC/PN mass ratios, &delta;¹³C and &delta;¹⁵N) of suspended particulate matter in Lake Erie, three tributary inflows, and the lake outflow between May and October, 2002. The data are used to 1) determine the relative contributions of allochthonous and autochthonous sources to suspended particulate matter, 2) identify possible sources of suspended particulate matter, and 3) compare suspended particulate matter in the eastern basin of Lake Erie with that in the central and western basins. Mean POC concentrations range from 175 to 4494 µg/L and mean PN concentrations range from 33 to 812 µg/L in this system. Mean POC/PN mass ratios are similar across all sampling locations, ranging between 4. 5 and 6. 9, and indicate that suspended particulate matter at these sites is mainly derived from autochthonous sources, particularly plankton. The ranges of &delta;¹³C (-34 to -22 ?) and &delta;¹⁵N (1 to 12 ?) identify terrestrial plants and soil matter, aquatic macrophytes, phytoplankton, and sewage as possible sources of suspended particulate matter at all sites. Plankton is probably the dominant source of suspended particulate matter at each site, with smaller contributions from allochthonous and other autochthonous sources. Significant differences in the concentration and isotope data between inflow and lake or outflow sites indicate that tributary inflows may receive greater contributions from terrestrial plants and soils and aquatic macrophytes than the lake and outflow. &delta;¹⁵N signatures also identify animal manure as a possible source of suspended particulate matter at the inflows. PN concentrations and &delta;¹⁵N signatures suggest that the shallowest nearshore sites close to Peacock Point in the eastern basin receive PN from a source that is not present at the other eastern basin sites or at the sites in the central and western basins. This source may be related to dreissenid mussels at these nearshore sites recycling nitrogen back into the water column.

<em>Cladophora glomerata</em> is a filamentous green alga that currently forms extensive blooms in nearshore areas of Lake Ontario, eastern Lake Erie, Lake Michigan, and isolated locations in Lake Huron. The biomass, areal coverage, algal bed characteristics, and tissue phosphorus concentrations of <em>Cladophora glomerata</em> were measured at 24 nearshore rocky sites along the northern shoreline of Lake Erie?s eastern basin between 1995-2002. Midsummer areal coverage at shallow depths (&le;5m) ranged from 4-100 %, with a median value of 96%. Peak seasonal biomass ranged from <1 to 940 g m^-2 dry mass (DM), with a median value of 171 g m^-2 DM. Tissue phosphorus varied seasonally, with initial high values in early May (0. 15 to 0. 27 % DM; median 0. 23 % DM) to midsummer seasonal low values during peak biomass (0. 03 to 0. 23 % DM; median 0. 06 % DM). A numerical <em>Cladophora</em> growth model (CGM) was revised and field-tested at 5 sites in eastern Lake Erie during 2002. The CGM is useful for: 1) Predicting <em>Cladophora</em> growth, biomass, and tissue phosphorus concentrations under non-point source P loading with no depth restrictions; 2) providing estimates of the timing and magnitude of the midsummer sloughing phenomenon; 3) determining the contribution of <em>Dreissena</em> invasion to the resurgence of <em>Cladophora</em> in eastern Lake Erie; and 4) developing management strategies for <em>Cladophora</em> abatement. The CGM was applied to investigate how the spatial and temporal patterns of <em>Cladophora</em> growth were influenced by the natural variability in environmental parameters in eastern Lake Erie. Seasonal patterns in <em>Cladophora</em> growth were strongly influenced by temperature, and peak depth-integrated biomass was strongly influenced by both available light and phosphorus. The photosynthetic capacity of field collected <em>Cladophora</em> was a poor predictor of the mid-summer sloughing phenomenon. The CGM, however, predicted that self-shading within the dense <em>Cladophora</em> mats would have caused negative growth rates at the base of the dense mats for 14 days prior to the sloughing event. The metabolic imbalances at the base of the <em>Cladophora</em> mats were driven primarily by the availability of light and were exacerbated by intermediate water temperatures (~23°C). The excellent agreement between model simulations and field data illustrates the ability of the CGM to predict tissue P and growth over a range of sites and depths in eastern Lake Erie and suggests potential for the model to be successfully applied in other systems.