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|Title:||Advection, Diffusion and Settling in the Coastal Boundary Layer of Lake Erie|
|Authors:||Elzawahry, Eldin Alaa|
|Keywords:||Civil Engineering;Civil Engineering|
|Abstract:||<p>Pollution in the coastal zones of the Great Lakes has become more serious in recent years. This is due to increased use of coastal water as a result of population and industrial growth. A substantial portion of the contaminants that enters a lake do so from the shoreline via discharges from sewer overflows, industrial outfaIIs and runoff. Such discharges contain particulates and other materials of density greater than that of lake water. Many heavy metals with toxic components are present in these fractions. The dynamic behavior of these particIes in the coastal and offshore waters is thus of great importance. The principal removal processes for these materials are transport and particle settling. An understanding of the characteristics of nearshore currents, diffusion and temperature patterns is essentiaI to determine their effect on removal processes, and in turn, on coastal biological and chemical processes. This study is limited to the physical fluid mechanics of coastal zones.</p> <p>The structure of the nearshore flow in the vicinity of Cleveland, Ohio is analyzed in detaiI in this study. The impact of Cleveland, one of the largest urban and industrial agglomerations on the shoreline of Lake Erie, in terms of additional loading is thought to be considerable. A computer program (ADVDIFF) was developed to calculate the mean flow, horizontal turbulent length and time scales, horizontal diffusivities and kinetic energy. ADVDIFF uses filtering techniques, spectral analyses and statistical analyses. Five episodes representing three different flow regimes which may exist in the coastal zone were chosen for special analyses.</p> <p>To generate the coastal currents, a rigid-lid, channel-type model with fine grid size in the coastal zone was used. A model originally developed by Simons (1983) was modified to incIude nonlinear acceIeration terms and two different forms of the vertical eddy viscosity. Also, a two dimensional x-y model developed by Simons and Lam (1982) was modified and used to expIain some of the observations. Both new modeIs (ERCH, ONELAY) were verified, calibrated and applied to Lake Erie.</p> <p>A computer program (SEDTRAN) was developed to predict the inflow sediment concentration distribution within the coastaI zone. SEDTRAN soIves numericaIIy the three dimensionaI time-dependent mass transport equation including the settIing term. The modeI uses the currents and diffusivities computed by ERCH and ONELAY and the statistical analyses, respectively. SEDTRAN was verified using several test examples, and partiaIIy vaIidated using the avaiIable data set. The modeI was applied to many cases of settIing activity that may take place in the coastaI zone. The results were used to define a representative influence zone for a pollutant source at CIeveIand.</p>|
|Appears in Collections:||Open Access Dissertations and Theses|
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