+2.7 m (0.0 to +8.8 ft)). Typical output examples presented in this report are 

 based on mlw datum. 



The REFDIF model was used in the linear mode with unit-amplitude waves 

 for all input conditions (Table Al) to transform waves from the deepwater 

 offshore boundary to the study area. Wave estimates for two historical storms, 

 the Blizzard of 1978 and the Halloween 1991 storm, were also simulated. For 

 each of these historical storms, four wave periods and associated directions, 

 selected from the WIS analysis, were used. Tidal datums of +4.1 and +3.7 m 

 (+13.6 and +12.0 ft), respectively, were used for the Blizzard of 1978 and the 

 Halloween 1991 storms. Numerical predictions were categorized for incident 

 wave angles of deg, ±22.5 deg, ±45.0 deg, and -13.0 deg. Estimates for 

 incident wave angles of ±22.5 deg and ±45.0 deg were grouped as a set. 

 Results were presented both in tables and plots for the six transects described 

 above. The structure of output information is the same for aU categories and 

 is briefly described next. 



An example of tabular output data for 11-sec waves from deg is pre- 

 sented in Table A3 for TR 1-3. Output shown in the table starts with model 

 predictions, followed by SneU's law estimates. Snell's law computations were 

 made only for shoaling and refraction coefficients requested for the physical 

 model study. The other computed quantities listed in the Snell's law tables are 

 included for comparing model versus linear theory. This revealing comparison 

 shows the order of magnitude of errors involved with the use of a simplified 

 wave transformation/propagation analysis. This tabular output was completed 

 for all six transects for the same input wave condition. 



The tabular output is self-explanatory, since column headings indicate the 

 quantity being listed. The first three lines in the tables are general informa- 

 tion, indicating that predictions are obtained either by the REFDIF model or by 

 linear wave theory. Printed next are the wave condition identifier (unchanged), 

 wave amplitude, incident wave direction, wave period, and transect number. 

 Headings for eight columns indicate what is printed under each column. These 

 include the I and J grid numbers, depth, computed amplitude and direction, 

 period, transect number, and wave-breaking index. The convention for wave 

 direction is that angles are posifive counterclockwise from the posifive x axis 

 and negative clockwise from the x axis. 



Wave height (=2.0 * amplitude) and water depth information listed in the 

 tables is also displayed by line plots. An example is shown in Figure A4 for 

 5-sec waves from deg for TR 3. Wave heights were plotted on positive 

 y-axis versus nodal points (grid numbers) on the x-axis. Depth values cor- 

 responding to the same grid points were also plotted on the negative y-axis 

 using a grid spacing of 152 m (500 ft). Depths were scaled (divided by 10) 

 for convenience of graphical output and wave heights were multiplied by 10 to 

 amplify small values resulfing from computafions. 



Analysis of REFDIF model results indicates that offshore waves arriving at 

 the neighborhood of the Saco River mouth can be greatly amplified. Wave 



Appendix A Saco Bay Nearshore Wave Estimates 



A17 



