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2D Modeling of Wind Waves on Inland Lakes
David Fuchs, 1999

In recent years wave ray approaches to model coastal areas have given way to 2Dspectral models. Third generation spectral models allow the development of a wave spectrum without any a priori limitations on spectral evolution. One such spectral model is SWAN (Simulation of Waves in the Nearshore). This finite depth model accounts for wind generated waves, whitecapping, bottom friction, refraction, depth induced breaking and shoaling, but does not account for diffraction.

The primary goal of this thesis is to determine the suitability of the SWAN model to predict significant wave height, peak period, and wave direction in the southern basin of Lake Winnipeg and Cedar Lake. A quasi nonstationary approach was developed to model storm events for Lake Winnipeg and Cedar Lake. Model predictions were compared to data obtained from an array of waveriders (directional and non-directional) deployed in the south basin of Lake Winnipeg in 1996. The array of waverider buoys allowed an opportunity to examine the temporal and spatial ability of the model to predict wave growth and decay in a relatively shallow lake. The quasi nonstationary method used in modeling the Lake Winnipeg wave climate with SWAN has produced reasonable results. Although there were some variation in predicted to measured spectra, modeled significant wave height were well reproduced within 6 to 15% of measured, peak periods within 0.5 seconds of measured and peak wave direction within 13' of measured.

Cedar Lake which is the reservoir for the Grand Rapids generating station provided a second opportunity to test the SWAN model on a shallow lake. The lake has an average depth of 6 to 8 m with a maximum fetch of approximately 15 km which better matches the assumptions of the SWAN model. The deployment of a single buoy at the east end of the lake allowed the possibility to measure a westerly storm. Modeling of Cedar Lake produced better results than Lake Winnipeg because it's area is smaller so there is less spatial variation in wind speeds and directions. The SWAN modeling of Cedar Lake produced significant wave heights within 4 to 9% of measured and peak periods within 0.33 seconds of measured.

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