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In comparison with wave modeling on an open coast, the complex geometry and bathymetry of estuaries, the unsteady conditions associated with estuarine circulation generated by tides and winds, and the relatively inadequate field data present a unique challenge. This study utilizes an unsteady, curvilinear spectral wave model that has the flexibility to resolve large geometric and bathymetric gradients and allows for consideration of unsteady forcing and currents to predict wind waves in Mobile Bay, Alabama. First, a laboratory data set on wave transformation over a circular shoal is chosen to test the curvilinear wave model. Excellent agreement is found between the numerical results and the laboratory measurements with a directional wave input and fine spatial resolution. Second, a three-dimensional circulation model is used to predict the varying current field and water levels that serve as the input to the wave model. The predictions of the wave model under unsteady forcing and ambient currents are then compared with the existing field measurement of wind waves in Mobile Bay. Numerical experiments are carried out to examine the effects of estuarine circulation and grid resolution on the model result. The study shows that the technique of linking a spectral wave model to a hydrodynamic model on curvilinear grids is an effective tool for wave prediction in estuaries. [ABSTRACT FROM AUTHOR]

The initial establishment and survival ofa salt marsh is regulated by a variety of factors, including salinity, sediment type, elevation, nutrient levels, and wave climate. Despite the obvious importance of wave climate on the existence or nonexistence of wetlands along shorelines of water bodies, there are currently few methods for its evaluation at wetland locations. This study used an existing wind-wave hindcast method to estimate wave climate at sites with and without Spartina alterniflora, along the shoreline in coastal Alabama. The sites with vegetation along the shoreline had lower wave levels than nearby sites without vegetation. Other sites with eroding stands of vegetation bad wave levels intermediate between the no-vegetation and vegetation sites. The upper limit of wave energy for (noneroding) salt marsh existence was a median significant wave height of about H = 0.1 meter and a corresponding 80 percentile (less than this level 80% of the time) significant wave height of H = 0.2 meter. Sites with less wave energy had vegetation along the shoreline. The results indicate that wave height frequency distribution based on wind-wave modeling hindcasts is an appropriate methodology for wave climate evaluation at wetland sites. The results can be used to minimize the size of breakwaters used in constructed wetlands. [ABSTRACT FROM AUTHOR]