bottom contours. No additional energy sources, such as winds, were added to 

 the existing Phase II wave conditions. Therefore, the simplified transformation 

 of waves from deep water to shallow water used during Phase III, was consid- 

 ered to be inadequate for this project. Revised North Atlantic hindcast data 

 (Hubertz et al. 1993) have recently been developed using the latest wave and 

 wind models. This new WIS hindcast provides more reliable data which 

 supersede aU information contained in previous WIS Reports, and was, there- 

 fore, used in the numerical modeling task for the Saco Bay project. 



Procedures to produce revised WIS information and examples of verifica- 

 tion against measurements are described elsewhere (Hubertz et al. 1993). The 

 revised 20-year U.S. Atlantic Coast WIS hindcast of wind and wave 

 information provides wave height, period, direction, and wind speed and direc- 

 tion at 3-hr intervals. These data are summarized for 108 stations along the 

 U.S. Atlantic Coast and for 3 stations along the north coast of Puerto Rico. 

 The revised hindcast gives summary tables for occurrences (by month) of spec- 

 tral wave height, peak period, peak mean wave direction, wind speed, and 

 wind direction for categories of 0.5 m (1.6 ft) 1.0 s, 22.5 deg, 2.5 m/s 

 (8.2 fps), and 45.0 deg, respectively. An example summary table for sta- 

 tion 99 in Saco Bay is provided in Table A2. In addition, for each station, 

 joint occurrences of height and period for 45-deg direction bands and all direc- 

 tions are presented. Finally, mean heights by month and year and maximum 

 heights by month and year, with associated peak periods and peak mean wave 

 directions are provided for each station. The 20-year time series of wind and 

 wave information, including spectra at each station, are also available from the 

 WIS archives as one-line records every 3 hr. 



Numerical Model Selection 



A time-independent spectral model called STWAVE was also considered 

 for simulating the nearshore wave transformation in the Saco Bay. Since 

 STWAVE does not have the capability to diffract waves around features such 

 as the Cape Elizabeth, High Head, Richmond Island, Prouts Neck, and several 

 other islands present inside the Saco Bay Sound, and given that these features 

 can significantly influence wave energy in the vicinity of the Saco River 

 mouth, it was necessary to consider a different model. The numerical model 

 REFDIF, a combined refraction-diffraction model, was therefore considered to 

 be better suited for this study, and was selected to transform waves within 

 Saco Bay. This model is suitable especially for varying bathymetry in 

 domains which include islands and are surrounded by complex land boun- 

 daries. Features of this model will be described later in this section. 



Modeling Issues, Procedures, and Input 



The modeling domain was extended 3.2 km (2 miles) offshore from WIS 

 station 99. This was done for considering possible land-boundary effects from 



Appendix A Saco Bay Nearshore Wave Estimates 



A11 



